21.04.2020

Carbon tetrachloride poisoning. Preparation of anhydrous pure organic solvents Toxic concentrations causing acute poisoning

The invention relates to the production of organochlorine products, in particular to the field of their purification by distillation. The installation for cleaning by distillation of organochlorine solvents contains a cube connected to the source of the initial solvent, installed on the latter and connected to it with a packed distillation column of periodic action, the top of which is connected to a reflux condenser, and the latter is connected from the exit side of it to the top of the distillation column and to collection tanks distillation product, while the plant is additionally equipped with at least two tanks for sampling products of reactive qualifications and a separator for sampling an aqueous intermediate fraction installed at the outlet of the dephlegmator and connected to a distillation column and a tank for collecting predgon through a separator, the distillation column is composed of three glass sides of the same height, hermetically connected to each other, and the diameter of the packed distillation column is from 0.06 to 0.07 of the height of the distillation column with the height of the latter from 2800 to 3200 mm, the cube is made of enameled cast iron, and the dephlegmator and containers for collecting the distillation product - from glass. EFFECT: invention makes it possible to increase the efficiency of the installation for purification by distillation of organochlorine products and to carry out deep purification by distillation of carbon tetrachloride, chloroform, trichlorethylene, methylene chloride and perchlorethylene. 6 n.p. f-ly, 1 ill.

Drawings to the RF patent 2241513

The invention relates to the production of organochlorine products, in particular to the field of their purification by distillation.

A known installation for the distillation of small industrial batches of solvents, containing a water evaporation chamber with electric heaters, a steam pipe, a water cooling system (see RF patent 2068729, class B 01 D 3/32, 10.11.1996.

This setup is quite simple. However, it does not make it possible to obtain especially pure chemical substances, which narrows the scope of this installation.

A known installation for the purification of organochlorine solvents, in particular methyl chlorides, containing a distillation column and a system of refrigerators-condensers installed at the outlet from the top of the column (see application WO 98/37044, class C 07 C 17/38, 27.08.1998).

This unit allows you to remove impurities from methyl chlorides. However, it also does not allow achieving high purity of the resulting product, which is associated with limited possibilities for separating the product after it leaves the top of the distillation column.

Closest to the invention in terms of technical essence and the result achieved in terms of the device, as the object of the invention, is a plant for purification by distillation of organochlorine solvents, containing a cube connected to the source of the initial solvent, installed on the latter and connected to it with a packed distillation column of periodic action, the top of which is connected to the dephlegmator, and the latter from the exit side is connected to the top of the distillation column and to the containers for collecting the distillation product (see Japanese patent JP 2001072623, class C 07 C 17/383, 03/21/2001).

This installation allows cleaning of organochlorine products. However, the efficiency of this installation is not used to the full extent, which is due to the fact that it does not allow obtaining several distillation products of varying degrees of purity.

A known method of purification of chlorohydrocarbons of the methane series, in particular chloroform and methyl chloride, as well as the allocation of methylene chloride in the form of a distillate of the rectification column. In this case, the purification of chloroform is carried out with sulfuric acid (see RF patent 2127245, class C 07 C 17/16, 10.03.1999).

However, this method does not allow obtaining products of reactive qualification. In particular, methylene chloride is obtained with a purity of only 99.7%.

A known method of purifying chloroform in a distillation mode using antimony pentachloride as an oxidizing agent (see RF patent No. 2096400, class C 07 C 17/383, 20.11.1997).

However, the use of a solvent can create problems in the disposal of production waste, which also narrows the scope this method purification of organochlorine solvents.

A known method of purification of organochlorine products from resin and soot, in particular methylene chloride, chloroform, carbon tetrachloride and trichlorethylene. The cleaning method consists in the fact that before evaporation or rectification fuel is introduced into organochlorine products with boiling ranges from 150 to 500 ° C (see RF patent 2051887, class C 07 C 17/42, 10.01.1996).

This method makes it possible to achieve the purification of organochlorine products from tar and soot, but does not make it possible to achieve the purity of distillation products of reactive qualifications, for example, “pure for analysis”.

Closest to the invention in terms of the method, as the object of the invention, is a method for purifying organochlorine solvents, which consists in the fact that the initial solvent is loaded into the cube, heated in the cube to the boiling point and the vapors are sent to the distillation column, from the last pair they enter the dephlegmator, where they are condensed, and from the reflux condenser, the condensate is fed through the separator to the upper part of the distillation column in the form of reflux, which, in contact with solvent vapors, condenses its non-volatile components, and the solvent in the form of a liquid phase enriched in non-volatile components is sent back to the cube with the formation of cube of the residue in this way, and the solvent vapors enriched in volatile non-condensed components are sent to a dephlegmator, in which they are cooled and condensed, and then, after stabilization of the operation of the distillation column, part of the condensate is sent in the form of reflux to the distillation column, and the other part of the condensate as a distillation product - in a container for collecting the distillate, (see. the above Japanese patent JP 2001072623).

However, this well-known method of purification of organochlorine products does not take into account the features of purification by distillation of such products as carbon tetrachloride, chloroform, trichlorethylene, methylene chloride and perchlorethylene, which does not allow full use of the capabilities of the distillation unit and obtain products of the required high degree of purity, in particular qualification products “chemically pure” or “special purity”.

The problem to which the present invention is directed is to increase the efficiency of the installation for purification by distillation of organochlorine products and carry out deep purification by distillation of carbon tetrachloride, chloroform, trichlorethylene, methylene chloride and perchlorethylene.

The specified problem in terms of the device, as an object of the invention, is solved due to the fact that the installation for purification by distillation of organochlorine solvents contains a cube connected to the source of the initial solvent, installed on the latter and communicated with it a packed distillation column of periodic action, the top of which is connected to a dephlegmator, and the latter is connected from the exit side to the top of the distillation column and to the tanks for collecting the distillation product, while the installation is additionally equipped with at least two tanks for sampling products of reactive qualifications and a separator installed at the outlet of the dephlegmator and connected to the distillation column and containers for collecting the aqueous intermediate fraction and pre-run through the separator, the distillation column is made up of three glass sides of the same height, hermetically connected to each other, and the diameter of the packed distillation column is from 0.06 to 0.07 of the height of the distillation column with the height of the latter from 2800 to 3200 mm, the cube is made of enameled cast iron, and the reflux condenser and containers for collecting distillation products are made of glass.

In terms of the method, as an object of the invention, this problem is solved due to the fact that the method of purification by distillation of carbon tetrachloride consists in the fact that technical carbon tetrachloride (CTC) is loaded into the cube, heated in the cube to the boiling point and the vapor is sent to the distillation column and further into the dephlegmator, where they are condensed, from the dephlegmator the condensate is fed through the separator to the upper part of the distillation column in the form of phlegm, which, in contact with CCA vapor, condenses its non-volatile components; thus forming a residue in the still, and the CCA vapors enriched in volatile non-condensed components are sent to a dephlegmator, in which they are cooled and condensed, and then, after stabilization of the operation of the distillation column, part of the condensate is sent in the form of reflux to the distillation column, and the other part of the condensate as a product distillation in containers for collecting the distillation product, while maintaining a reflux ratio equal to 4, the loading of technical ChKhU into the cube is carried out at room temperature of ChKhU, while the pressure in the cube is maintained equal to atmospheric pressure, ChKhU is heated to a temperature of 75-77 ° C and for 30 -40 min, all condensate from the reflux condenser is sent back to the distillation column in the form of reflux and the reflux flow is maintained from 180 to 200 dm 3 /h, and the condensate from the reflux condenser is fed into the distillation column through the separator, through which the aqueous intermediate fraction and pre-run are taken from the condensate, and after that, a part of the condensate is taken after the reflux condenser - products of reactive qualifications into separate containers in the following sequence: “pure”, “pure for analysis”, “chemically pure”, and the selection of the specified condensate is carried out in the following quantities: aqueous intermediate fraction from 2.0 up to 2.5% vol, prerun from 2 to 6% vol, “pure” - from 28 to 30% vol, “pure for analysis” - from 25 to 28% vol and “chemically pure” - from 28 to 30% vol , everything from the amount loaded into the CHU cube, after that the distillation process is stopped, the distillation residue is disposed of, and the distillation products are sent to their destination.

Another method, as an object of the invention, is a method of purification by distillation of chloroform, which consists in the fact that technical chloroform is loaded into the cube, heated in the cube to the boiling point and the vapors are sent to the distillation column and then to the dephlegmator, where they are condensed, condensate from the dephlegmator it is fed through the separator to the upper part of the distillation column in the form of phlegm, which, in contact with chloroform vapor, condenses its non-volatile components, chloroform in the form of a liquid phase enriched with non-volatile components is sent back to the cube with the formation of a residue in the cube, and chloroform vapor, enriched with volatile non-condensed components, they are sent to a reflux condenser, in which they are cooled and condensed, and then, after stabilization of the distillation column, part of the condensate is sent in the form of phlegm to the distillation column, and the other part of the condensate, as a distillation product, is sent to containers for collecting distillation products, with at the same time, a reflux ratio of 4 is maintained, technical chloroform is loaded into the cube at room temperature of chloroform, while the pressure in the cube is maintained equal to atmospheric pressure, chloroform is heated to a temperature of 60-65 ° C and within 30-40 minutes all condensate from the dephlegmator is sent back to the distillation column in the form of reflux and the reflux flow is maintained from 110 to 130 dm 3 /h, and the condensate from the reflux condenser is fed into the distillation column through a separator, through which the aqueous intermediate fraction and prerun are taken from the condensate, and then a part is taken after the reflux condenser condensate - products of reactive qualifications into separate containers in the following sequence: “pure”, “pure for analysis”, “chemically pure”, and the selection of the specified condensate is carried out in the following quantities: aqueous intermediate fraction from 2.0 to 3.0% vol, predistillation from 10 to 12% vol, “clean” - from 20 to 25% vol, “clean for analysis” - from 28 to 30% vol and “chemically pure” - from 12 to 15% vol, all from the amount loaded into the cube chloroform, after which the distillation process is stopped, the VAT residue is disposed of, and the distillation products are directed to their destination.

Another method, as an object of the invention, is a method of purification by distillation of trichlorethylene, which consists in the fact that technical trichlorethylene is loaded into the cube, heated in the cube to the boiling point and the vapors are sent to the distillation column and then to the dephlegmator, where they are condensed, and from dephlegmator, the condensate is fed through a separator to the upper part of the distillation column in the form of phlegm, which, in contact with trichlorethylene vapor, condenses its non-volatile components, trichlorethylene in the form of a liquid phase enriched in non-volatile components is sent back to the cube with the formation of a residue in the cube, and the vapor trichlorethylene, enriched with volatile non-condensed components, is sent to a dephlegmator, in which they are cooled and condensed, and then, after stabilization of the operation of the distillation column, part of the condensate is sent in the form of phlegm to the distillation column, and the other part of the condensate as a distillation product is sent to containers for collecting the distillation product , while maintaining a reflux ratio equal to 4, loading trichlorethylene technical into the cube is carried out at room temperature of trichlorethylene, while maintaining a pressure equal to atmospheric pressure in the cube, heating trichlorethylene to a temperature of 89-95 ° C and within 30-40 minutes all condensate from the reflux condenser is sent back to the distillation column in the form of reflux, the reflux flow is maintained from 100 to 120 dm 3 /h, and the condensate from the reflux condenser is fed into the distillation column through the separator, through which the aqueous intermediate fraction and pre-run are taken from the condensate, and then taken after dephlegmator part of the condensate - products of reactive qualifications into separate containers in the following sequence: “pure”, “chemically pure”, “special purity”, and the selection of the specified condensate is carried out in the following quantities: aqueous intermediate fraction from 1.0 to 2.0% vol. , pre-run from 15 to 17% vol, “clean” - from 18 to 20% vol, “chemically pure” - from 28 to 30% vol and “special purity” - from 10 to 12% vol, all from the amount loaded into the cube trichlorethylene, after which the distillation process is stopped, the VAT residue is disposed of, and the distillation products are directed to their destination.

Another method, as an object of the invention, is a method of purification by distillation of methylene chloride, which consists in the fact that technical methylene chloride is loaded into the cube, heated in the cube to the boiling point and the vapors are sent to the distillation column and then to the dephlegmator, where they are condensed, and from the reflux condenser, the condensate is fed through the separator to the upper part of the distillation column in the form of phlegm, which, in contact with methylene chloride vapor, condenses its non-volatile components, methylene chloride in the form of a liquid phase enriched in non-volatile components is sent back to the still with the formation of a residue in the still , and vapors of methylene chloride, enriched with volatile non-condensed components, are sent to a dephlegmator, in which they are cooled and condensed, and then, after stabilization of the operation of the distillation column, part of the condensate is sent in the form of reflux to the distillation column, and the other part of the condensate as a distillation product is sent to the tank to collect the distillation product, while maintaining a reflux ratio equal to 4, the loading of technical methylene chloride into the cube is carried out at room temperature of methylene chloride, while the pressure in the cube is maintained equal to atmospheric pressure, the initial solvent is heated to a temperature of 40-44 ° C and for 30-40 min, the entire condensate from the reflux condenser is sent back to the distillation column in the form of reflux and the reflux flow is maintained from 200 to 240 dm 3 /h, and the condensate from the reflux condenser is fed into the distillation column through the separator, through which the aqueous intermediate fraction and pre-run are taken from the condensate , and after that, a part of the condensate is taken after the reflux condenser - products of reactive qualifications into separate containers in the following sequence: “pure” and “chemically pure”, and the selection of the specified condensate is carried out in the following quantities: aqueous intermediate fraction from 1 to 3% vol, prerun from 13 to 15% vol, “pure” - from 20 to 23.5% vol and “chemically pure” - from 45 to 50% vol, all from the amount of methylene chloride loaded into the cube, after that the distillation process is stopped, the distillation residue is disposed of, and the products of distillation are sent to their destination.

And another method of purification by distillation of perchlorethylene, which consists in the fact that technical perchlorethylene is loaded into the cube, heated in the cube to the boiling point and the vapors are sent to the distillation column and then to the dephlegmator, where they are condensed, and from the dephlegmator the condensate is fed through the separator to the upper part distillation column in the form of reflux, which, in contact with perchlorethylene vapor, condenses its non-volatile components, perchlorethylene in the form of a liquid phase enriched with non-volatile components is sent back to the cube with the formation of a residue in the cube, and perchlorethylene vapor enriched with highly volatile non-condensed components is sent into a dephlegmator, in which they are cooled and condensed, and then, after stabilization of the operation of the distillation column, part of the condensate is sent in the form of phlegm to the distillation column, and the other part of the condensate as a distillation product is sent to a container for collecting the distillation product, while maintaining a reflux ratio equal to 4, the loading of technical perchlorethylene into the cube is carried out at room temperature of perchlorethylene, while the pressure in the cube is maintained equal to atmospheric pressure, the perchlorethylene is heated to a temperature of 125-130 ° C and within 30-40 minutes all the condensate from the dephlegmator is sent back to the distillation column in in the form of phlegm, maintain a phlegm flow from 120 to 150 dm 3 /h, and the condensate from the reflux condenser is fed into the distillation column through the separator, through which the aqueous intermediate fraction and pre-run are taken from the condensate, and then part of the condensate is taken after the reflux condenser - products of reactive qualifications in separate containers in the following sequence: “clean”, “chemically pure”, and the selection of the specified condensate is carried out in the following quantities: aqueous intermediate fraction from 2.0 to 5.0% vol, prerun from 7 to 9% vol, “clean” - from 40 to 43% vol and “chemically pure” - from 38 to 40% vol, all from the amount of perchlorethylene loaded into the still, after which the distillation process is stopped, the distillation residue is disposed of, and the distillation products are directed to their destination.

In the course of the analysis, it was revealed that the implementation of a distillation column, a reflux condenser and containers for collecting a distillation product made of glass, for example, Simax glass, assembled from three drawers of the same height, hermetically connected to each other with a diameter of 0.06 to 0.07 of height of the distillation column with a total height of the distillation column from 2800 to 3200 mm, makes it possible to obtain products of qualification “chemically pure” and “pure for analysis” during rectification with a total yield of pure product up to 75% of its initial amount, which is quite economically justified. In addition, during the installation of the installation, materials were used, the use of which during distillation cleaning allows obtaining products of reactive qualifications, namely, a cast-iron cube with an enamel coating and fluororubber gaskets at the junctions of the installation structural elements.

In the course of the study, optimal conditions were obtained for purification by distillation of carbon tetrachloride, chloroform, trichlorethylene, methylene chloride and perchlorethylene. For carbon tetrachloride, the following parameters were set: reflux ratio equal to 4, loading the initial solvent into a cube at room temperature and heating the initial product to a temperature of 75-77°C. Heating to a lower temperature does not allow organizing the distillation process, and heating above the specified range does not allow to achieve stable operation of the column. The operation of the distillation column “on itself” for 30-40 minutes, when all the condensate from the dephlegmator is sent back to the distillation column as phlegm and the reflux flow is maintained from 180 to 200 l / h, allows reaching a stable operating mode, in which it is possible to achieve the required degree of purification of carbon tetrachloride. The supply of condensate from the reflux condenser to the distillation column through the separator makes it possible to select from the condensate the aqueous intermediate fraction and pre-run. All of the above allows you to start the selection after the dephlegmator of products of reactive qualifications into separate containers in the following sequence: “pure”, “pure for analysis”, “chemically pure”.

Given the stable nature of the operation of the distillation column, it is possible to determine the amount of the selected purified distillation product of each of the purity qualifications, namely, the selection in the following quantities: aqueous intermediate fraction from 2.0 to 2.5% vol., prerun from 2 to 6% vol., “pure ” - from 28 to 30% vol, “pure for analysis” - from 25 to 28% vol and “chemically pure” - from 28 to 30% vol, all from the amount of loaded initial solvent.

Similarly, the above modes of operation were experimentally obtained in the purification by distillation of chloroform, trichlorethylene, methylene chloride and perchlorethylene. As a result, it was possible to solve the problem posed in the invention - to increase the efficiency of the installation for purification by distillation of organochlorine products and to carry out high-quality purification by distillation of carbon tetrachloride, chloroform, trichlorethylene, methylene chloride and perchlorethylene.

The drawing shows circuit diagram installations for purification by distillation of organochlorine solvents.

The installation for purification by distillation of organochlorine solvents contains a cube 1 connected to the source of the initial product, installed on the latter and communicated with it a packed distillation column 2 of periodic action, the top of which is connected to a reflux condenser 3, and the latter is connected to the top of the distillation column 2 from the exit side of it, and to tanks 4, 5, 6 for collecting the distillation product of reactive qualification. The plant is additionally equipped with a separator 8 installed at the outlet of the reflux condenser 3 and connected to the distillation column 2 and tanks 7, 9, respectively, for collecting the pre-run and selecting the aqueous intermediate fraction. The distillation column 2 is made of three glass tsargs of the same height, hermetically connected to each other using gaskets made of fluoroelastomer. The diameter "D" of the packed distillation column is from 0.06 to 0.07 of the height "H" of the distillation column 2 with the height of the latter from 2800 to 3200 mm. Cube 1 is made of enameled cast iron, and containers 4, 5, 6 for collecting the distillation product are made of glass.

The method of purification by distillation of carbon tetrachloride produced as follows. Technical carbon tetrachloride is loaded into cube 1, heated in cube 1 to the boiling point and the vapor is sent to the distillation column 2 and then the vapor is sent to the dephlegmator 3, where the vapor is condensed by cooling. Further, phlegm is fed into the distillation column 2 from its top, which, in contact with carbon tetrachloride vapor, condenses the non-volatile components of carbon tetrachloride, thus forming a residue, the latter is sent back to the still, and carbon tetrachloride vapor with highly volatile non-condensed components is sent to the dephlegmator 3, into in which the volatile component is cooled and condensed. After that, part of the condensate is sent in the form of reflux to the distillation column 2, and the other part as a distillation product is sent to containers 4, 5, 6 to collect the distillation product. During the distillation, the reflux ratio is maintained at 4. Carbon tetrachloride is loaded into cube 1 at room temperature of carbon tetrachloride, while pressure equal to atmospheric pressure is maintained in cube 1. Then carbon tetrachloride is heated to a temperature of 75-77°C and within 30-40 min all condensate from the reflux condenser 3 is sent back to the distillation column 2 in the form of reflux and the reflux flow is maintained from 180 to 200 dm 3 /h, and the condensate from the reflux condenser is fed into the distillation column 2 through the separator 8, through which the aqueous intermediate fraction is withdrawn from the condensate into a special container 9, and then the condensate - the product of reactive qualifications is withdrawn into separate containers in the following sequence : “clean” into container 4, “clean for analysis” into container 5 and “chemically pure” into container 6, and the selection of the indicated condensate is carried out in the following quantities: aqueous intermediate fraction from 2.0 to 2.5% vol, prerun from 2 to 6% vol, “pure” - from 28 to 30% vol, “pure for analysis” - from 25 to 28% vol and “chemically pure” - from 28 to 30% vol, all from the amount of tetrachloride loaded into the cube 1 carbon. After that, the distillation process is stopped, the distillation residue is disposed of, and the distillation products are directed to their destination.

Similarly, but taking into account the above regime parameters and parameters for the selection of rectification products, chloroform, trichlorethylene, methylene chloride and perchlorethylene are purified.

The feedstock - technical carbon tetrachloride GOST 4-84 "Higher" and "First grades" is loaded from barrels under vacuum (P=0.5 atm).

Cube 1 is heated with steam (P=0.7-1.2 atm).

Vapors of carbon tetrachloride rise along the packed part of the distillation column 2, and then pass through the steam line, the vapor temperature, in which the temperature is measured with a thermometer (t=75-77°C). Having passed the steam pipeline, the vapors are condensed in the dephlegmator 3, which is cooled cold water.

The condensed vapors enter the separator 8 and return back to the distillation column 2. Reflux return 180-200 dm 3 /hour. The distillation column 2 operates in the "on itself" mode for 30-40 minutes.

In the process of operation of the distillation column 2, the water intermediate fraction accumulating in the upper layer of the separator 8 is withdrawn “to itself”, for which the valve is opened and the aqueous fraction is drained into the collector 9. As the water is withdrawn, the product in the separator 8 gradually becomes clearer. Distillation column 2 works “for itself” until carbon tetrachloride is completely clarified.

The number of selections depends on the quality of the feedstock, namely the presence of water in it, and ranges from 8 to 10 dm 3 .

After the operation of the distillation column 2 “on itself”, the selection of predgon begins in the amount of 8-24 dm 3 . The valve is opened and the pre-run enters the collector (tank) 7. After the selection of the pre-run, the temperature in the upper part of the distillation column changes. When the temperature changes in the next two predrun samples within 1-0.5°C and a positive laboratory analysis is obtained, you can proceed to the selection of the finished product.

First, the qualification product “pure” is taken in the amount of 112-120 dm 3 into the container (collector) 4, for which the valves at its inlet are opened, then the qualification product “pure for analysis” is taken in the amount of 100-112 dm 3, for this the valve is closed on tank 4 and open the valve on tank 5. Having filled tank 5, close the valve on this tank and open the valve on tank 6 to select the product of “chemically pure” qualification in the amount of 112-120 dm 3 . Having finished the selection of the finished product, close the valves at the outlet of the dephlegmator.

To complete the operation of the column, the supply of steam to the jacket of the cube 1 is stopped. The top of the distillation column 2 is cooled to room temperature, then the water is turned off at the dephlegmator 3. The cube is cooled to 30°C. Predgon, product and VAT residue is subjected to physico-chemical methods of quality analysis. VAT residue is poured into waste barrels. Distillation column 2 begin to prepare for the next start, as described above.

The feedstock (GOST 20015-88 chloroform, the highest and first grade or technical grade) is loaded from the collection barrels under vacuum (P=0.5 atm). Of the latter, the feedstock is poured into the cube in the amount of 400 dm 3 .

Chloroform vapors rise along the packed part of the distillation column 2, pass a steam pipeline, the vapor temperature in which is measured with a thermometer (t=60-65°C). Having passed the steam pipeline, the vapors are condensed in the dephlegmator 3, which is cooled with cold water.

The condensed vapors enter the separator 8 and return back to the distillation column 2. The column 2 operates in the "on itself" mode for 30-40 minutes.

During the operation of the column “to itself”, the aqueous intermediate fraction accumulated in the upper layer of the separator 8 is selected, for which the valve is opened at the inlet to the container (collector) 9. The number of withdrawals depends on the quality of the feedstock, namely, on the presence of water in it. The total amount of selection is 8-12 dm 3 .

After the operation of the column "on itself" the selection of the pre-run begins in the amount of 40-48 dm 3 . The pre-run enters the tank 7. After the selection of the pre-run ( average temperature in the cube 62°C, and in the upper part of the distillation column - 61.2°C) proceed to the selection of the commercial product.

First, the “pure” qualification product is taken in the amount of 80-100 dm 3 into container 4, for which we open the valves at its inlet, then the “pure for analysis” qualification product is taken in the amount of 112-120 dm 3, for this we close the valve on container 4 and open the valve on the container 5. Having filled the container 5, close the valve on this container 5 and open the valve of the container 6 to select the product of qualification “chemically pure” in the amount of 48-60 dm 3 . After finishing the selection of the finished product, close the valves.

To complete the operation of the distillation column 2, the steam supply to the jacket of the cube 1 is stopped. The cube 1 is cooled with water through the jacket. Cool the top of the distillation column 2 to room temperature, then turn off the cooling water on the dephlegmator 3. The cube is cooled to 30°C. Preliminarily, the pre-run, the product and the VAT residue are subjected to physico-chemical methods of analysis for quality, 21 dm 3 of chloroform is used for washing. VAT residue is poured into waste barrels. The predgon is poured into waste barrels. The product from containers 4, 5, 6 is sent for packing, having been previously stabilized with ethyl alcohol (1% by weight of the finished product), the column is started to be prepared for the next start-up, as described above.

Feedstock (technical trichlorethylene) is loaded from barrels under vacuum (P=0.5 atm). Of the latter, the feedstock is poured into the cube in the amount of 400 dm 3 .

Before starting work, the columns open the air line. Cube 1 is heated with steam (P=0.5 atm). Why open the corresponding valve on the steam supply line from the steam generator and valves for steam condensate sampling.

Vapors of trichlorethylene rise through the packed part of the distillation column 2, pass through a steam pipeline, the vapor temperature in which is measured by a thermometer (t=89-95°C). Having passed the steam pipeline, the vapors are condensed in the dephlegmator 3, which is cooled with cold water.

The condensed vapors enter the separator 8 and return back to the distillation column 2. The column 2 operates in the "on itself" mode for 30-40 minutes. Phlegm consumption 100-120 dm 3 /h.

After the operation of the column "on itself" the selection of the pre-run begins in the amount of 60-68 dm 3 . The pre-run enters the tank 7. After the pre-run is selected, the commercial product is selected.

First, the “clean” qualification product is taken in the amount of 72-80 dm 3 into container 4, for which the valves at its inlet are opened, then the “chemically pure” qualification product is taken in the amount of 112-120 dm 3, for this, the valve on container 4 is closed and open the valve on the container 5. Having filled the container 5, close the valve on this container 5 and open the valve of the container 6 to select the product of qualification “special pure” in the amount of 40-48 dm 3 . After finishing the selection of the finished product, close the valves.

To complete the operation of the distillation column 2, the steam supply to the jacket of the cube 1 is stopped. The cube 1 is cooled with water through the jacket. Cool the top of the distillation column 2 to room temperature, then turn off the cooling water on the dephlegmator 3. The cube is cooled to 30°C. Preliminarily, the pre-run, the product and the VAT residue are subjected to physico-chemical methods of analysis for quality. VAT residue is poured into waste barrels. The predgon is poured into waste barrels. The product from containers 4, 5, 6 is sent for packing, the column is being prepared for the next start, as described above.

Feedstock (technical methylene chloride) is loaded from barrels under vacuum (P=0.5 atm). Of the latter, the feedstock is poured into the cube in the amount of 400 dm 3 .

Vapors of methylene chloride rise through the packed part of the distillation column 2, pass the steam pipeline, the vapor temperature in which is measured by a thermometer (t=40-44°C). Having passed the steam pipeline, the vapors are condensed in the dephlegmator 3, which is cooled with cold water.

The condensed vapors enter the separator 8 and return back to the distillation column 2. The column 2 operates in the "on itself" mode for 30-40 minutes. Phlegm consumption 200-240 dm 3 /h.

After the operation of the column “on itself”, the selection of the pre-run begins in the amount of 52-60 dm 3 . The pre-run enters the tank 7. After the pre-run is selected, the commercial product is selected.

First, the “pure” qualification product is taken in the amount of 80-94 dm 3 into container 4, for which the valves at its inlet are opened, then the “chemically pure” qualification product is taken in the amount of 180-200 dm 3, for this, the valve on container 4 is closed and open the valve on the container 5. Having finished the selection of the finished product, close the valves.

Feedstock (technical perchlorethylene) is loaded from barrels under vacuum (P=0.5 atm). Of the latter, the feedstock is poured into the cube in the amount of 400 dm 3 .

Vapors of perchlorethylene rise through the packed part of the distillation column 2, pass a steam pipeline, the vapor temperature in which is measured by a thermometer (t=125-130°C). Having passed the steam pipeline, the vapors are condensed in the dephlegmator 3, which is cooled with cold water.

The condensed vapors enter the separator 8 and return back to the distillation column 2. The column 2 operates in the "on itself" mode for 30-40 minutes. Phlegm consumption is 120-150 dm 3 /h.

After the operation of the column “on itself”, the selection of the predgon begins in the amount of 28-36 dm 3 . The pre-run enters the tank 7. After the pre-run is selected, the commercial product is selected.

First, the “pure” qualification product is taken in the amount of 160-172 dm 3 into container 4, for which the valves at its inlet are opened, then the “chemically pure” qualification product is taken in the amount of 152-160 dm 3, for this, the valve on container 4 is closed and open the valve on the container 5. Having finished the selection of the finished product, close the valves.

To complete the operation of the distillation column 2, the steam supply to the jacket of the cube 1 is stopped. The cube 1 is cooled with water through the jacket. Cool the top of the distillation column 2 to room temperature, then turn off the cooling water on the dephlegmator 3. The cube is cooled to 30°C. Preliminarily, the pre-run, the product and the VAT residue are subjected to physico-chemical methods of analysis for quality. VAT residue is poured into waste barrels. The predgon is poured into waste barrels. The product from containers 4, 5 is sent for packing, the column is being prepared for the next start, as described above.

The present invention can be used in the chemical and perfume industries.

CLAIM

1. Installation for purification by distillation of organochlorine solvents, containing a cube connected to the source of the initial solvent, installed on the latter and communicated with it, a packed distillation column of periodic action, the top of which is connected to a reflux condenser, and the latter is connected to the top of the distillation column and to tanks for collecting the distillation product, characterized in that the unit is additionally equipped with at least two tanks for sampling products of reactive qualifications and a separator installed at the outlet of the reflux condenser and connected to the distillation column and tanks for collecting the aqueous intermediate fraction and pre-run through the separator, distillation column is composed of three glass sides of the same height, hermetically connected to each other, and the diameter of the packed distillation column is from 0.06 to 0.07 of the height of the distillation column with the height of the latter from 2800 to 3200 mm, the cube is made of enameled cast iron, and the dephlegmator and containers for collecting distillation products - made of glass.

2. The method of purification by distillation of carbon tetrachloride, which consists in the fact that technical carbon tetrachloride (CTC) is loaded into the cube, heated in the cube to the boiling point and the vapor is sent to the distillation column and then to the dephlegmator, where they are condensed, from the dephlegmator condensate through the separator is fed into the upper part of the distillation column in the form of phlegm, which, in contact with CCA vapor, condenses its non-volatile components; uncondensed components are sent to a reflux condenser, in which they are cooled and condensed, and then, after stabilization of the operation of the distillation column, part of the condensate is sent in the form of reflux to the distillation column, and the other part of the condensate as a distillation product is sent to a container for collecting the distillation product, characterized in that that the phlegm number is maintained equal to 4, the technical CHU is loaded into the cube at room temperature of the CHU, while the pressure in the cube is maintained equal to atmospheric pressure, the CHU is heated to a temperature of 75-77 ° C and within 30-40 minutes all condensate from the dephlegmator is sent back into the distillation column in the form of phlegm and maintain the flow of phlegm from 180 to 200 dm 3 /h, and the condensate from the dephlegmator is fed into the distillation column through the separator, through which the aqueous intermediate fraction and pre-run are taken from the condensate, and then part of the condensate is taken after the dephlegmator - products of reactive qualifications into separate containers in the following sequence: “pure”, “pure for analysis”, “chemically pure”, and the selection of the indicated condensate is carried out in the following quantities: aqueous intermediate fraction from 2.0 to 2.5 vol.%, pre-run from 2 to 6 vol.%, "pure" - from 28 to 30 vol.%, "pure for analysis" - from 25 to 28 vol.% and "chemically pure" - from 28 to 30 vol.%, all by quantity loaded into the CHU cube, after that the distillation process is stopped, the distillation residue is disposed of, and the distillation products are sent to their destination.

3. The method of purification by distillation of chloroform, which consists in the fact that technical chloroform is loaded into the cube, heated in the cube to the boiling point and the vapors are sent to the distillation column and then to the dephlegmator, where they are condensed, from the dephlegmator the condensate is fed through the separator to the upper part of the distillation column in the form of reflux, which, in contact with chloroform vapor, condenses its non-volatile components, chloroform in the form of a liquid phase enriched with non-volatile components is sent back to the cube with the formation of a residue in the cube, and chloroform vapor enriched with highly volatile non-condensed components is sent to a reflux condenser, in which they are cooled and condensed, and then, after stabilization of the operation of the distillation column, part of the condensate is sent in the form of phlegm to the distillation column, and the other part of the condensate, as a distillation product, to a container for collecting the distillation product, characterized in that the reflux number is maintained equal to 4, technical chloroform is loaded into the cube at room temperature of chloroform, while the pressure in the cube is maintained equal to atmospheric pressure, chloroform is heated to a temperature of 60-65 ° C and within 30-40 minutes all condensate from the dephlegmator is sent back to the distillation column in the form phlegm and maintain a reflux flow from 110 to 130 dm 3 /h, and the condensate from the dephlegmator is fed into the distillation column through the separator, through which the aqueous intermediate fraction and pre-run are taken from the condensate, and after that part of the condensate is taken after the dephlegmator - products of reactive qualifications into separate containers in the following sequence: “pure”, “pure for analysis”, “chemically pure”, and the selection of the specified condensate is carried out in the following quantities: aqueous intermediate fraction from 2.0 to 3.0 vol.%, prerun from 10 to 12 vol. .%, “pure” - from 20 to 25 vol.%, “pure for analysis” - from 28 to 30 vol.% and “chemically pure” - from 12 to 15 vol.%, all from the amount of chloroform loaded into the cube, after that, the distillation process is stopped, the distillation residue is disposed of, and the distillation products are directed to their destination.

4. A method for cleaning the distillation of trichlorethylene, which consists in the fact that technical trichlorethylene is loaded into the cube, heated in the cube to the boiling point and the vapor is sent to the distillation column and then to the dephlegmator, where they are condensed, and from the dephlegmator the condensate is fed through the separator to the upper part distillation column in the form of reflux, which, in contact with trichlorethylene vapor, condenses its non-volatile components, trichlorethylene in the form of a liquid phase enriched with non-volatile components is sent back to the cube with the formation of a residue in the cube, and trichlorethylene vapor enriched with highly volatile non-condensed components is sent to a reflux condenser, in which they are cooled and condensed, and then, after stabilization of the operation of the distillation column, part of the condensate is sent in the form of phlegm to the distillation column, and the other part of the condensate, as a distillation product, to a container for collecting the distillation product, characterized in that the reflux number is maintained equal to 4, technical trichlorethylene is loaded into the cube at room temperature of trichlorethylene, while the pressure in the cube is maintained equal to atmospheric pressure, trichlorethylene is heated to a temperature of 89-95 ° C and within 30-40 minutes all condensate from the dephlegmator is sent back to the distillation column in the form phlegm and maintain a reflux flow from 100 to 120 dm 3 /h, and the condensate from the dephlegmator is fed into the distillation column through the separator, through which the aqueous intermediate fraction and pre-run are taken from the condensate, and then part of the condensate is taken after the dephlegmator - products of reactive qualifications into separate containers in the following sequence: “pure”, “chemically pure”, “special purity”, and the selection of the specified condensate is carried out in the following quantities: aqueous intermediate fraction from 1.0 to 2.0 vol.%, prerun from 15 to 17 vol. %, “pure” - from 18 to 20 vol.%, “chemically pure” - from 28 to 30 vol.% and “special purity” - from 10 to 12 vol.%, all from the amount of trichlorethylene loaded into the cube, after that the distillation process is stopped, the distillation residue is disposed of, and the distillation products are directed to their destination.

5. The method of purification by distillation of methylene chloride, which consists in the fact that technical methylene chloride is loaded into the cube, heated in the cube to the boiling point and the vapors are sent to the distillation column and then to the dephlegmator, where they are condensed, and from the dephlegmator the condensate is fed through the separator to the upper part of the distillation column in the form of reflux, which, in contact with methylene chloride vapor, condenses its non-volatile components, methylene chloride in the form of a liquid phase enriched with non-volatile components is sent back to the cube with the formation of a residue in the cube, and methylene chloride vapor enriched volatile non-condensed components are sent to a reflux condenser, in which they are cooled and condensed, and then, after stabilization of the operation of the distillation column, part of the condensate is sent in the form of phlegm to the distillation column, and the other part of the condensate, as a distillation product, to a container for collecting the distillation product, characterized in that that maintain a reflux ratio equal to 4, the loading of technical methylene chloride into the cube is carried out at room temperature of methylene chloride, while the pressure in the cube is maintained equal to atmospheric pressure, the initial solvent is heated to a temperature of 40-44 ° C and within 30-40 minutes the entire condensate from the reflux condenser is sent back to the distillation column in the form of reflux and the reflux flow is maintained from 200 to 240 dm 3 /h, and the condensate from the reflux condenser is fed into the distillation column through a separator, through which the aqueous intermediate fraction and pre-run are taken from the condensate, and then taken after dephlegmator, part of the condensate - products of reactive qualifications into separate containers in the following sequence: “pure” and “chemically pure”, and the selection of the specified condensate is carried out in the following quantities: aqueous intermediate fraction from 1 to 3 vol.%, prerun from 13 to 15 vol. %, “pure” - from 20 to 23.5 vol.% and “chemically pure” - from 45 to 50 vol.%, all from the amount of methylene chloride loaded into the cube, after that the distillation process is stopped, the distillation residue is disposed of, and the products distillations are sent to their destination.

6. The method of purification by distillation of perchlorethylene, which consists in the fact that technical perchlorethylene is loaded into the cube, heated in the cube to the boiling point and the vapors are sent to the distillation column and then to the dephlegmator, where they are condensed, and from the dephlegmator the condensate is fed through the separator to the upper part distillation column in the form of reflux, which, in contact with perchlorethylene vapor, condenses its non-volatile components, perchlorethylene in the form of a liquid phase enriched with non-volatile components is sent back to the cube with the formation of a residue in the cube, and perchlorethylene vapor enriched with highly volatile non-condensed components is sent into a reflux condenser, in which they are cooled and condensed, and then, after stabilization of the operation of the distillation column, part of the condensate is sent in the form of reflux to the distillation column, and the other part of the condensate as a distillation product is sent to a container for collecting the distillation product, characterized in that the reflux ratio is maintained equal to 4, the loading of technical perchlorethylene into the cube is carried out at room temperature of perchlorethylene, while the pressure in the cube is maintained equal to atmospheric pressure, the perchlorethylene is heated to a temperature of 125-130 ° C and within 30-40 minutes all the condensate from the dephlegmator is sent back to the distillation column in in the form of phlegm and maintain a phlegm flow from 120 to 150 dm 3 /h, and the condensate from the dephlegmator is fed into the distillation column through the separator, through which the aqueous intermediate fraction and the pre-run are taken from the condensate, and then part of the condensate is taken after the dephlegmator - products of reactive qualifications in individual containers in the following sequence: “pure”, “chemically pure”, and the selection of the specified condensate is carried out in the following quantities: aqueous intermediate fraction from 2.0 to 5.0 vol.%, prerun from 7 to 9 vol.%, “pure ” - from 40 to 43 vol.% and “chemically pure” - from 38 to 40 vol.%, all from the amount of perchlorethylene loaded into the still, after which the distillation process is stopped, the distillation residue is disposed of, and the distillation products are directed to their destination.

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UNION OF THE SOVIET SHIRISHI EDERRESPUBLIK 07 S 07 S 19/06 RETENII RSKOY I wish to improve the implementation of the promotion of xo zoldnazol, ORS 12 in general to ots-Khkhloushkin n and the state konitet of the USSR MADE INVENTIONS AND O 3 NR TY DESCRIPTION I(71) Institute of Inorganic Chemistry.. , and electrochemistry of the Academy of Sciences of the Georgian SSR "Foreign Literature", 1958, p. 393-396.2. Workshop on organic chemistry, I., "Iir", 1979, p. 376 (prototype) 3 E.N.Napvop, S.E.Ie 1 oap - "Zpot 8.pcs 1.sev. 1 eyyeg", 971, p.461-472..80295 4) (57) METHOD OF CLEANING , FOUR CENTURY CARBON by drying with a desiccant and distillation, it is noted that, for the purpose of the process technology and the degree of drying, a mixture of the complement of the formula CoK C 1 + Soy is used, where 11- benz,1,3- tnadi1 - benz, 1,3-selenium at a mass ratio: Co K C 1 (25-30): in the presence of a mixture of 2.0-3.0 to the original fourth carbon, and the stages of oregonka are combined in time. 117295 2nd includes the stage of boiling solvent at reflux for 18 hours using P O as a drying agent, followed by 5 column distillation. The consumption of P 05 per 1 liter of solvent is 25-30 g, and the water content in the target product is not lower than 0.00523.0 The disadvantages of the known method are complexity 1, the presence of two stages - drying and distillation and the duration of the process, which significantly complicates its technology, also15 high water content in the target product.The aim of the invention is to simplify the process technology and increase the degree of drying. water is the main undesirable impurity of SS and therefore all purification methods usually include the stage of drying and distillation of the solvent.Drying and distillation are the final stages of the purification process of SS 1 and therefore the removal of water from SS 1 is an important task, SS 1 does not mix well with water (0.08%) and in many cases distillation is sufficient for purification. Water is removed in the form of a zeotropic mixture, which boils at 6 °C and contains 95.9 solvents. A ternary azeotropic mixture of vault (4.3%) and ethanol (9.7) boils at 61.8 C. When higher requirements are made for the purification of SS 1, distillation without preliminary drying of the solvent is unsuitable. There is a known method for purifying carbon tetrachloride, according to which SS 1 is pre-dried and then distilled on a column. Drying is carried out over CaC 1, and distillation of ad P 05 SS 1, dried over calcined CaC 1 and distilled from a flask with an effective reflux 0r in a water bath, and in some cases from a quartz flask with a reflux condenser. When using CC 14, for thermochemical measurements, the solvent is subjected to fractional distillation twice on a column with a vacuum jacket, each time discarding the first and last portion of a quarter of the total amount of distillate G 1. However, simple distillation of the solvent without the use of desiccants does not make it possible to obtain a solvent with a low water content. In methods based on the use of desiccants and subsequent distillation, a preliminary long-term contact of the solvent with a desiccant is necessary, the choice of which for CC 1 is limited. Among the desiccants, calcined CaC 1 is the most acceptable. It has been shown that 50CC 1 cannot be dried over sodium, since an explosive mixture is formed under these conditions. This purification method is lengthy, has many steps, and is ineffective.55 The method closest to the invention is the purification method for CC 1, which is 1 where d "benz, 1,3-thiadiaeol; k - benz, 1,3-selenediazol; at a mass ratio of Co KS 1Co K., C 1 25" 30: 1 and the total amount of the mixture is 2.0-3.0 wt, .G with respect to the initial carbon tetrachloride, and the stages of drying and distillation are combined in time and space. the indicated ligands Pu K) quantitatively decompose in the presence of traces of water. These complexes are insoluble in all ordinary solvents. - solvents. In solvents with water impurities, instead of the usual dissolution, the destruction of the complex occurs with the formation of a free ligand. and a hydrated cobapt ion, In solvents containing there is a trivalent nitrogen atom in the molecule, the reaction of substitution of ligand molecules by solvent molecules proceeds. Such solvents include amines, amides, and iitriles, as well as some heterocycles. sulfur- or selenium-containing diazoles, using the polarography method, as well as UV and visible spectra of the resulting solutions, it was shown that the interaction between the ligand and the complexing agent in nitrogen-containing media or in media containing traces of water does not take place. Complexes of cobalt with aromatic diazoles can only be obtained in absolutely anhydrous media that do not contain a nitrogen atom. In all cases, when these complexes are introduced into solvents containing moisture impurities, the sum of the spectra of the ligand and the cobapt ion corresponds to the resulting spectrum, and the polarograms clearly show the waves of the lgand and the cobalt ion. 25 The reaction of the decomposition of cobapt complexes with these diazoles under the action of water molecules proceeds very quickly and the solvent takes on the color of a hydrated cobalt ion. Instant binding of traces of water by a desiccant (cobapt complexes proceeds by the mechanism of hydrate formation, hydrate (the transfer of the coordinated cobalt atom in the complex to hdratnro-3 5. bathed non is dissolved; therefore, the coloring of the solvent in the color of gnd, rated cobolt ions can serve as a characteristic sign of the removal of water impurities from a solvent, It is known that an anhydrous solid has a pale blue color di-, -tri-, tetra- and hexahydrates, respectively, violet, purple, red and red-brown.: The cobalt complex with diazoles is a plate olive color, upon introduction of which into SS 14, depending on the amount of water in 50 of it, the solvent is painted in one of the indicated colors of hydrated Co. The ability of cobap"ta complexes with benzo,1,3-thia- and selenediazole" to decompose in the presence of traces of water depends on the nature of the ligand, more precisely, on the nature of the key heteroatom in the ligand molecule. nature of the heteroatom (H, Re) in the ligand and increases significantly when the sulfur atom is replaced by a selenium atom in the diazole hetero ring. At a very low water content in CC 1, the most effective desiccant is the cobalt complex with benz,1,3-selenpiaeol. When the water content in the solvent in an amount not exceeding 0.013, a complex of cobalt with benz,1,3-tiddiaeol can also serve as a desiccant. Consequently, a mixture of these complexes can serve as a desiccant in a wide range of water content in the solvent. 1,3-selenediaeol can be mixed as an impurity to the cobalt complex with benz,1,3-thiadiazole, which will bind most of the water in the solvent. The required degree of purification of CC 1 in each particular case can be achieved by varying the proportion of the components of the mixture. However, in order for the composition to have maximum efficiency as a drying agent, it is necessary to use the minimum weight fraction of the cobalt complex with benz,1,3-selenediaeol in the mixture. Thus, simultaneously with the effect of hydrate formation from an anhydrous cobalt complex, which is easily the basis of the proposed method, the composition of the drying mixture of cobalt complexes with aromatic diazoles is a characteristic feature this method purification of SS 14. Instant binding of traces of water by cobalt complexes based on these diaeols when they are introduced into SS 14 eliminates the need for preliminary 18-hour reflux of the solvent over PO. Therefore, a mixture of complexes can be introduced into the solvent directly at the stage of distillation, thereby combining the stages of drying and distillation. The decomposition products of the complexes - the ligand aromatic diaeol and the hydrated cobalt ion have much more high temperature boiling than SS, therefore, during distillation, they cannot turn into a distillate. The latter is collected in a receiver with a .7295 ratio of cobalt complexes with sbene, 1,3-thiadiaeol and bene, 1,3-selendiaeol. The results are shown in the table, in order to prevent contact of the distillate with air. The excess mixture of cobalt complexes with diaeols, when injected into SS 1, settles at the bottom of the flask of the distillation apparatus, in which the purified solvent retains the color of the hydrated cobalt ion until the end of the process. Water content in the distillate is determined by standard Fleur titration. EXAMPLE 1. 300 mp CC+ is introduced into the flask of the distillation apparatus, a mixture consisting of 10 g of a cobolt complex with beneo,1,3-thiadiazole and O, 4 g is added cobalt complex with benzoate with 2,1,3-selenediazol ( total mixtures of cobalt complexes 23 and distilled. A fraction with a b.p. p 5 MP/min Duration t - O 3 0750 10: 15: 1.0007 25 30 0.0005 0 Process Thus, the invention provides a simplification of the process technology by eliminating the stage of preliminary contact of the solvent 3 0 with the desiccant of the drying and distillation stage combined in time and space, reducing the time required for cleaning SS 1 due to the rapid binding of traces of water in the solvent with a mixture of cobalt complexes with aromatic diols, and achieving a drying depth of SS 1, up to 0.00053 residual water, which increases the degree of drying is an order of magnitude, Sevnoarat, from 14 g of 2 1,3-ticobalion (general cobalt is added to the stake a complex of adiagold with ben, the fraction is 200 mp) e 0.0005 N. Dzhugan Tekhred I. Astvlosh Correction V, Vutyaga Circulation 409 of the State Committee for Acquisitions and Discoveries, Zh, Raushskaya n snoe d. 4 measures 2, 300 MP bu distillation an mixture consisting of cobapta with beneo and 0.4 g of a complex of o,1,3-selendiae about a mixture of complex distilled, Selected ip. up to 76.5-77 OS e of water in the distillation distillation 5 cp / mi t process. measures 3-8. The process for example 2 with a different order 7145/16 VNIIII Gosu on cases 113035, Ios

Application

3521715, 16.12.1982

INSTITUTE OF INORGANIC CHEMISTRY AND ELECTROCHEMISTRY AS GSSR

TSVENIASHVILI VLADIMIR SHALVOVICH, GAPRINDASHVILI VAKHTANG NIKOLAEVICH, MALASHKHIA MARINA VALENTINOVNA, HAVTASI NANULI SAMSONOVNA, BELENKAYA INGA ARSENEVNA

IPC / Tags

Link Code

Carbon tetrachloride purification method

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Methods for cleaning organic solvents depend on the nature and purpose of the solvent. In most cases, organic solvents are individual compounds and can be characterized by their physicochemical properties. The most elementary solvent purification operation is simple or fractional distillation. However, distillation often fails to get rid of a number of impurities, including small amounts of water.

By conventional purification methods, a solvent of approximately 100% purity can be obtained. With the help of adsorbents, in particular molecular sieves (zeolites), this problem is solved more efficiently and with less time. In laboratory conditions, ion exchangers are most often used for this purpose - zeolites of the NaA or KA brands.

When preparing pure anhydrous solvents precautions should be especially strictly observed, since most organic solvents are flammable substances, the vapors of which form explosive mixtures with air, and in some of them (ethers) explosive peroxide compounds are formed during long-term storage. Many organic solvents are highly toxic, both when their vapors are inhaled and when they come into contact with the skin.

All operations with flammable and combustible organic solvents must be carried out in a fume hood with ventilation running, gas burners and electric heaters turned off. Liquids should be heated and distilled in a fume hood on preheated baths filled with an appropriate heat transfer medium. When distilling an organic liquid, it is necessary to constantly monitor the operation of the refrigerator.

If flammable solvents (gasoline, diethyl ether, carbon disulfide, etc.) are accidentally spilled, immediately extinguish all sources of open fire and turn off electric heaters (de-energize the working room during the day). The place where the liquid is spilled should be covered with sand, the contaminated sand should be collected with a wooden scoop and poured into a garbage container installed in the open air.

When drying solvents, active drying agents should not be used until pre-coarse drying with conventional drying agents has been carried out. Thus, it is forbidden to dry crude diethyl ether with sodium metal without first drying it with calcined CaCl2.

When working with ethers and other substances (diethyl ether, dioxane, tetrahydrofuran), during the storage of which peroxide compounds can be formed, peroxides are first removed from them, and then distilled and dried. Anhydrous organic solvents should be distilled carefully. All elements of the distillation unit (distillation flask, reflux condenser, refrigerator, alonge, distillate receiver) are preliminarily dried in an oven. The distillation is carried out without access to air, and the alonge is supplied with a calcium chloride tube filled with ascarite and fused CaCl2 to absorb CO2 and H2O. It is advisable to discard the first portion of the distillate, which serves to flush the entire equipment.

Methods for purification and dehydration of the most commonly used solvents are discussed below.

Acetone

Acetone CH3COCH3 - colorless liquid; d25-4 = 0.7899; tboil = 56.24 °С; n20-D = 1.3591. Easily ignited. Vapors form explosive mixtures with air. Technical acetone usually contains water, with which it mixes in any ratio. Sometimes acetone is contaminated with methanol, acetic acid and reducing agents.

A test for the presence of reducing substances in acetone is carried out as follows. To 10 ml of acetone add 1 drop of 0.1% aqueous solution of KMnO4; after 15 minutes at room temperature, the solution should not be colorless.

For purification, acetone is heated for several hours with anhydrous K2CO3 (5% (wt.)) in a flask with a reflux condenser, then the liquid is poured into another flask with a reflux condenser 25-30 cm high and distilled over anhydrous K2CO3 (about 2% (wt.) ) and crystalline KMnO4, which is added to acetone until a stable violet color appears in a water bath. In the resulting acetone, there is no longer methyl alcohol, but there is a small amount of water.

To completely remove water, acetone is repeatedly distilled over anhydrous CaCl2. To do this, 1 liter of acetone is poured into a 2-liter round-bottom flask equipped with an efficient reflux condenser closed with a calcium chloride tube with CaCl2, 120 g of CaCl2 are added and boiled in a water bath with closed electric heating for 5-6 hours. Then the reaction flask is cooled and acetone is poured into another similar flask with a fresh portion of CaCl2 and boil again for 5-6 hours. After that, the reflux condenser is replaced with a descending one, to which, using an alonge connected to a calcium chloride tube filled with CaCl2, a receiving flask cooled with ice is attached and acetone is distilled over CaCl2.

Instead of such a long and laborious operation, which often leads to the condensation of acetone, it is better to use NaA zeolite. With prolonged exposure of acetone over this zeolite (5% (mass.)) is achieved absolute acetone.

In small quantities, very pure acetone can be obtained from the adduct (addition product) of acetone and NaI, which decomposes even at low heating, releasing acetone. To do this, when heated in a water bath, dissolve 100 g of NaI in 440 ml of dry, freshly distilled acetone. The resulting solution is rapidly cooled to -3° C. by immersing the vessel in a mixture of ice and NaCl. The separated solid NaI-C3H6O adduct is separated on a Buchner funnel, transferred to a distillation flask and heated on a water bath. On gentle heating, the adduct decomposes, and the liberated acetone is distilled off. The distillate is dried over anhydrous CaCl2 and redistilled with a reflux condenser over CaCl2. Regenerated NaI can be reused for the same reaction.

An express method for purifying acetone from methyl alcohol and reducing substances is as follows: a solution of 3 g of AgNO3 is added to 700 ml of acetone in a 1-liter flask. in 20 ml of distilled water and 20 ml of 1 N. NaOH solution. The mixture is shaken for 10 min, after which the precipitate is filtered off on a funnel with a glass filter, and the filtrate is dried with CaSO4 and refluxed over CaCl2.

Acetonitrile

Acetonitrile CH3CN is a colorless liquid with a characteristic ethereal odor; d20-4 = 0.7828; tboil = 81.6°С; n20-D = 1.3442. It is miscible with water in all respects and forms an azeotropic mixture (16% (wt.) H2O) with tboil = 76°C. A good solvent for a number of organic substances, in particular amine hydrochlorides. It is also used as a medium for carrying out some reactions, which it accelerates catalytically.

Acetonitrile is a strong inhalation poison and can be absorbed through the skin.

For absoluteization, acetonitrile is distilled twice over P4O10, followed by distillation over anhydrous K2CO3 to remove traces of P4O10.

You can pre-dry the acetonitrile over Na2SO4 or MgSO4, then mix with CaH2 until the evolution of gas (hydrogen) stops and distill over P4O10 (4-5 g/l). The distillate is refluxed over CaH2 (5 g/l) for at least 1 h, then slowly distilled, discarding the first 5 and the last 10% of the distillate.

Benzene

Benzene C6H6 - colorless liquid; d20-4 = 0.8790; tmelt = 5.54 °С; tboil = 80 10°С; n20-D = 1.5011. Benzene and its homologues, toluene and xylenes, are widely used as solvents and azeotropic drying media. Benzene should be handled with care due to its flammability and toxicity, as well as the formation of explosive mixtures with air.

Benzene vapors with repeated exposure disrupt the normal function of the hematopoietic organs; in the liquid state, benzene is strongly absorbed through the skin and irritates it.

Technical benzene contains up to 0.02% (wt.) of water, some thiophene and some other impurities.

Benzene forms an azeotropic mixture with water (8.83% (wt.) H2O) with tboil = 69.25°C. Therefore, during the distillation of wet benzene, water is almost completely distilled off with the first portions of the distillate (cloudy liquid), which are discarded. As soon as the clear distillate begins to distill, the drying process can be considered complete. Additional drying of distilled benzene is usually carried out with calcined CaCl2 (for 2-3 days) and sodium wire.

In the cold season, care must be taken to ensure that the distilled benzene does not crystallize in the refrigerator tube, washed with cold water (4-5 ° C).

Benzene and other hydrocarbons dried with metallic sodium are hygroscopic, that is, they can absorb moisture.

Commercial commercial benzene contains up to 0.05% (wt.) of C4H4S thiophene (tboil = 84.12°C; tmelt = 38.3°C), which cannot be separated from benzene either by fractional distillation or crystallization (freezing). Thiophene in benzene is detected as follows: a solution of 10 mg of isatin in 10 ml of conc. H2SO4 is shaken with 3 ml of benzene. In the presence of thiophene, the sulfuric acid layer turns blue-green.

Benzene is purified from thiophene by repeated shaking with conc. H2SO4 at room temperature. Under these conditions, thiophene is predominantly sulfonated rather than benzene. For 1 liter of benzene take 80 ml of acid. The first portion of H2SO4 turns blue-green. The lower layer is separated, and benzene is shaken with a new portion of acid. Purification is carried out until a faint yellow color of the acid is achieved. After separation of the acid layer, the benzene is washed with water, then with 10% Na2CO3 solution and again with water, after which the benzene is distilled.

A more efficient and simpler method for removing thiophene from benzene is boiling 1 liter of benzene with 100 g of Raney nickel in a flask under reflux for 15-30 minutes.

Another way to purify benzene from thiophene is to fractionally crystallize it from ethyl alcohol. A saturated solution of benzene in alcohol is cooled to about -15°C, solid benzene is quickly filtered off and distilled.

Dimethyl sulfoxide

Dimethyl sulfoxide (CH3) 2SO - colorless syrupy liquid without pronounced odor; d25-4 = 1.1014; tboil = 189°С (with decomposition); tm = 18.45 °С; n25-D = 1.4770. Miscible with water, alcohols, acetone, ethylacetone, dioxane, pyridine and aromatic hydrocarbons, but not miscible with aliphatic hydrocarbons. Universal solvent for organic compounds: ethylene oxide, heterocyclic compounds, camphor, resins, sugars, fats, etc. It also dissolves many inorganic compounds, for example, at 60 ° C it dissolves 10.6% (wt.) KNO3 and 21.8% CaCl2. Dimethyl sulfoxide is practically non-toxic.

For purification, dimethyl sulfoxide is kept for a day over active Al2O3, after which it is distilled twice at a pressure of 267–400 Pa (2–3 mm Hg) over fused KOH (or BaO) and stored over NaA zeolite.

Under the action of reducing agents, dimethyl sulfoxide turns into sulfide (CH3) 2S, and under the action of oxidizing agents - into sulfone (CH3) 2SO2, incompatible with acid chlorides of inorganic and organic acids.

N,N-Dimethylformamide

N,N-Dimethylformamide HCON(CH3)2 - a colorless, mobile liquid with a slight specific odor; d25-4 = 0.9445; tboil = 153°С; n24-D = 1.4269. Miscible in any ratio with water, alcohol, acetone, ether, chloroform, carbon disulfide, halogenated and aromatic compounds; aliphatic hydrocarbons dissolves only when heated.

Dimethylformamide is distilled at atmospheric pressure without decomposition; decomposes under the influence of ultraviolet rays with the formation of dimethylamine and formaldehyde. The dimethylformamide reagent, in addition to methylamine and formaldehyde, may contain methylformamide, ammonia and water as impurities.

The dimethylformamide is purified as follows: 10 g of benzene and 4 ml of water are added to 85 g of dimethylformamide, and the mixture is distilled. First, benzene with water and other impurities is distilled off, and then the pure product.

diethyl ether

Diethyl ether (C2H5) 2O is a colorless, easily mobile, volatile liquid with a peculiar odor; d20-4 = 0.7135; tboil = 35.6°С; n20-D = 1.3526. Extremely flammable; Vapors form explosive mixtures with air. Vapors are approximately 2.6 times heavier than air and can spread over the surface of the work table. Therefore, it is necessary to ensure that nearby (up to 2-3 m) from the place of work with the ether, all gas-burners were extinguished, and open-coil electric stoves were disconnected from the mains.

When diethyl ether is stored under the action of light and atmospheric oxygen, explosive peroxide compounds and acetaldehyde are formed in it. Peroxy compounds are the cause of extremely violent explosions, especially when attempting to distill ether to dryness. Therefore, when determining the boiling point and non-volatile residue, the ether should first be checked for the content of peroxides. In the presence of peroxides, these determinations cannot be made.

Many reactions have been proposed for the detection of peroxide in diethyl ether.

1. Reaction with potassium iodide KI. A few milliliters of ether are shaken with an equal volume of 2% aqueous KI acidified with 1-2 drops of HCl. The appearance of a brown color indicates the presence of peroxides.

2. Reaction with titanyl sulfate TiOSO4. The reagent is prepared by dissolving 0.05 g of TiOSO4 in 100 ml of water, acidified with 5 ml of diluted H2SO4 (1:5). On shaking 2-3 ml of this reagent with 5 ml of the test ester containing peroxide compounds, a yellow color appears.

3. Reaction with sodium dichromate Na2Cr2O7. To 3 ml of ether add 2-3 ml of 0.01% Na2Cr2O7 aqueous solution and one drop of diluted H2SO4 (1:5). The mixture is shaken vigorously. The blue color of the ether layer indicates the presence of peroxides.

4. Reaction with ferrothiocyanate Fe(SCN)2. A colorless solution of Fe(SCN)2 under the action of a drop of a liquid containing peroxide turns red due to the formation of ferrithiocyanate (Fe2+ > Fe3+). This reaction makes it possible to detect peroxides in concentrations up to 0.001% (mass.). The reagent is prepared as follows: 9 g of FeSO4-7H2O are dissolved in 50 ml of 18% HCl. Add granulated zinc and 5 g of sodium thiocyanate NaSCN to the solution in an open vessel; after the disappearance of the red color add another 12 g of NaSCN, shake gently and the solution is separated by decantation.

Iron(II) sulfate is used to remove peroxides. When shaking 1 l of ether, usually take 20 ml of a solution prepared from 30 g of FeSO4-7H2O, 55 ml of H2O and 2 ml of conc. H2SO4. After washing, the ether is shaken with 0.5% KMnO4 solution to oxidize acetaldehyde to acetic acid. Then the ether is washed with 5% NaOH solution and water, dried for 24 h over CaCl2 (150-200 g CaCl2 per 1 l of ether). The CaCl2 is then filtered off on a large pleated filter paper and the ether is collected in a dark glass bottle. The bottle is tightly closed with a cork stopper with a calcium chloride tube, bent at an acute angle, filled with CaCl2 and glass wool swabs inserted into it. Then, having opened the flask, sodium wire is quickly introduced into the ether, at the rate of 5 g per 1 liter of ether.

After 24 hours, when no more hydrogen bubbles are emitted, another 3 g of sodium wire per 1 liter of ether is added and after 12 hours the ether is poured into a distillation flask and distilled over sodium wire. The receiver must be protected by a calcium chloride tube with CaCl2. The distillate is collected in a dark glass bottle, which, after adding 1 g of sodium wire per 1 liter of ether, is closed with a cork stopper with a calcium chloride tube and stored in a cold and dark place.

If the surface of the wire has changed greatly and hydrogen bubbles are released again when the wire is added, then the ether should be filtered into another flask and another portion of sodium wire should be added.

Convenient and very effective method purification of diethyl ether from peroxides and at the same time from moisture - passing the ether through a column with active Al2O3. Columns with a height of 60-80 cm and a diameter of 2-4 cm, filled with 82 g of Al2O3, are sufficient to purify 700 ml of ether containing a significant amount of peroxide compounds. Spent Al2O3 can be easily regenerated if a 50% acidified aqueous solution of FeSO4-7H2O is passed through the column, washed with water, dried, and thermally activated at 400-450°C.

Absolute ether is a highly hygroscopic liquid. The degree of moisture absorption by ether during its storage can be judged by the blueness of the anhydrous white powder CuSO4 when it is introduced into ether (a colored hydrate CuSO4-5H2O is formed).

dioxane

Dioxane (CH2) 4O is a colorless flammable liquid with a slight odor; d20-4 = 1.03375; tboil = 101.32 °С; tmelt = 11.80°C; n20-D = 1.4224. Miscible with water, alcohol and ether in any ratio. Forms azeotropic mixtures with water and alcohol.

Technical dioxane contains ethylene glycol acetal, water, acetaldehyde and peroxides as impurities. The method of purification of dioxane should be chosen depending on the degree of contamination, which is determined by adding sodium metal to dioxane. If a brown precipitate is formed, then the dioxane is heavily contaminated; if the surface of sodium changes slightly, then dioxane contains few impurities and is purified by distillation over sodium wire.

Heavily contaminated dioxane is purified as follows: 0.5 l of dioxane, 6 ml of conc. HCl and 50 ml of H2O are heated in a silicone (oil) bath under a stream of nitrogen in a flask with a reflux condenser at 115–120°C for 12 h.

After cooling, the liquid is shaken with small portions of molten KOH to remove water and acid. Dioxane forms the top layer, it is separated and dried with a fresh portion of KOH. The dioxane is then transferred to a clean distillation flask and heated at reflux over 3-4 g of sodium wire for 12 hours. Purification is considered complete if the sodium surface remains unchanged. If all the sodium has reacted, then it is necessary to add a fresh portion and continue drying. Dioxane, which does not contain peroxide compounds, is distilled on a column or with an effective reflux condenser at normal pressure. Purification of dioxane from peroxides is carried out in the same way as the purification of diethyl ether.

Methyl alcohol (methanol)

Methyl alcohol (methanol) CH3OH is a colorless, easily mobile, flammable liquid, with an odor similar to that of ethyl alcohol; d20-4 = 0.7928; tboil = 64.51 °С; n20-D = 1.3288. Miscible in all respects with water, alcohols, acetone and other organic solvents; not miscible with aliphatic hydrocarbons. It forms azeotropic mixtures with acetone (tbp = 55.7°C), benzene (tbp = 57.5°C), carbon disulfide (tbp = 37.65°C), and also with many other compounds. With water, methyl alcohol does not form azeotropic mixtures, so most of the water can be removed by distillation of the alcohol.

Methyl alcohol is a strong poison that affects mainly nervous system and blood vessels. It can enter the human body through the respiratory tract and skin. Especially dangerous when taken orally. The use of methyl alcohol in laboratory practice is allowed only in cases where it cannot be replaced by other, less toxic substances.

Synthetic absolute methyl alcohol, produced by the industry, contains only traces of acetone and up to 0.1% (mass.) of water. Under laboratory conditions, it can be prepared from technical CH3OH, in which the content of these impurities can reach 0.6 and even 1.0%. In a flask with a capacity of 1.5 l with a reflux condenser, protected by a calcium chloride tube with CaCl2, 5 g of magnesium chips are placed, they are poured with 60-70 ml of methyl alcohol containing no more than 1% water, an initiator is added - 0.5 g of iodine (or the corresponding the amount of methyl iodide, ethyl bromide) and heated until the latter dissolves. When all magnesium passes into methylate (a white precipitate forms at the bottom of the flask), 800-900 ml of technical CH3OH are added to the resulting solution, boiled in a flask under reflux for 30 minutes, after which alcohol is distilled off from a 50 cm high reflux flask, collecting a fraction with a boiling point of 64.5-64.7°C (at normal pressure). The receiver is supplied with a calcium chloride tube with CaCl2. The water content of the alcohol obtained in this way does not exceed 0.05% (mass.). Absolute methyl alcohol is stored in a vessel protected from atmospheric moisture.

Additional drying of methyl alcohol containing 0.5-1% water can be carried out with magnesium metal without initiating the reaction. To do this, 10 g of magnesium chips are added to 1 liter of CH3OH, and the mixture is left in a reflux flask protected by a calcium chloride tube with CaCl2. The reaction starts spontaneously, and soon the alcohol boils. When all the magnesium has dissolved, boiling is maintained by heating in a water bath for some more time, after which the alcohol is distilled, discarding the first portion of the distillate.

Anhydrous methyl alcohol is also obtained by holding it over NaA or KA zeolite or by passing it through a column filled with these molecular sieves. To do this, you can use a laboratory-type column.

The presence of acetone in methyl alcohol is determined by a test with sodium nitroprusside. The alcohol is diluted with water, alkalized and a few drops of a freshly prepared saturated aqueous solution of sodium nitroprusside are added. In the presence of acetone, a red color appears, which intensifies upon acidification with acetic acid.

To remove acetone, the following method is proposed: 500 ml of CH3OH are boiled for several hours with 25 ml of furfural and 60 ml of 10% NaOH solution in a flask with a reflux condenser, and then the alcohol is distilled off on an efficient column. Resin remains in the flask - the product of the interaction of furfural with acetone.

Petroleum ether, gasoline and naphtha

During the distillation of light gasoline, a number of low-boiling hydrocarbon fractions are obtained, which are used as solvents. Vapors of these hydrocarbons have a narcotic effect.

The industry produces the following reagents:

The high volatility of petroleum ether, gasoline and naphtha, their easy flammability and the formation of explosive mixtures with air require special care when working with them.

Petroleum ether, gasoline and naphtha must not contain impurities of unsaturated and aromatic hydrocarbons.

The presence of unsaturated hydrocarbons is usually established by two reagents: 2% solution of Br2 in CCl4 and 2% aqueous solution KMnO4 in acetone. To do this, a reagent solution is added dropwise to 0.2 ml of hydrocarbon in 2 ml of CCl4 and the color change is observed. The sample is considered negative if no more than 2-3 drops of bromine solution or KMnO4 solution become discolored.

Unsaturated hydrocarbons can be removed by repeated 30-minute shaking on a mechanical shaker of a portion of hydrocarbons with 10% (v/v) conc. H2SO4. After shaking with each portion of acid, the mixture is allowed to settle, then separated bottom layer. When the acid layer stops coloring, the hydrocarbon layer is shaken vigorously with several portions of a 2% KMnO4 solution in a 10% H2SO4 solution until the color of the KMnO4 solution no longer changes. At the same time, unsaturated hydrocarbons and partially aromatic hydrocarbons are almost completely removed. To completely remove aromatic hydrocarbons, it is necessary to shake hydrocarbons (petroleum ether, etc.) with oleum containing 8-10% (mass.) SO3 on a rocking chair. A bottle with a ground stopper, in which shaking is performed, is wrapped in a towel. After separation of the acid layer, the hydrocarbon fraction is washed with water, 10% Na2CO3 solution, again with water, dried over anhydrous CaCl2 and distilled over sodium wire. It is recommended to store petroleum ether over CaSO4 and distill before use.

The traditional chemical method of purifying saturated hydrocarbons from unsaturated hydrocarbons is very time consuming and can be replaced by adsorption. Impurities of many unsaturated compounds are removed by passing the solvent through a glass column with active Al2O3 and especially on zeolites, such as NaA.

Tetrahydrofuran

Tetrahydrofuran (CH2) 4O is a colorless mobile liquid with an ethereal odor; d20-4 = 0.8892; tboil = 66°С; n20-D = 1.4050. Soluble in water and most organic solvents. Forms an azeotropic mixture with water (6% (wt.) H2O), tboil = 64°C. Tetrahydrofuran is prone to the formation of peroxide compounds, so be sure to check for the presence of peroxides in it (see Diethyl ether). Peroxides can be removed by boiling with a 0.5% suspension of Cu2Cl2 for 30 min, after which the solvent is distilled and shaken with melted KOH. Upper layer tetrahydrofuran is separated, 16% (mass.) KOH is added to it again and the mixture is refluxed for 1 hour in a flask under reflux. Then tetrahydrofuran is distilled over CaH2 or LiAlH4, 10-15% of the head fraction is discarded and about 10% of the residue is left in the cube. The head fraction and the bottom fraction are added to the technical products intended for purification, and the collected middle fraction is dried over a sodium wire. The purified product is stored without access to air and moisture.

Chloroform

Chloroform CHCl3 is a colorless mobile liquid with a characteristic sweet smell; d20-4 = 1.4880; tboil = 61.15°С; n20-D = 1.4455. Soluble in most organic solvents; practically insoluble in water. Forms an azeotropic mixture with water (2.2% (wt.) H2O), tboil = 56.1 °C. It is non-flammable and does not form explosive mixtures with air, but it is toxic - it acts on internal organs, especially the liver.

Chloroform almost always contains up to 1% (wt.) ethyl alcohol, which is added to it as a stabilizer. Another impurity of chloroform can be phosgene, which is formed during the oxidation of chloroform in the light.

The test for the presence of phosgene is performed as follows: 1 ml of a 1% solution of n-dimethylaminobenzaldehyde and diphenylamine in acetone is shaken with chloroform. In the presence of phosgene (up to 0.005%), an intense yellow color appears after 15 minutes. Chloroform is purified by shaking three times with separate portions of conc. H2SO4. For 100 ml of chloroform, each time take 5 ml of acid. Chloroform is separated, washed 3-4 times with water, dried over CaCl2 and distilled.

Purification of chloroform is also achieved by slowly passing the preparation through a column filled with active Al2O3 in the amount of 50 g per 1 liter of chloroform.

Chloroform should be stored in dark glass bottles.

carbon tetrachloride

Carbon tetrachloride CCl4 is a colorless non-flammable liquid with a sweet smell; d20-4 = 1.5950; tboil = 76.7°С; n25-D = 1.4631. Practically insoluble in water. Forms an azeotropic mixture with water (4.1% (wt.) H2O), tboil = 66°C. Dissolves various organic compounds. It has a less narcotic effect than chloroform, but surpasses it in toxicity, causing severe liver damage.

Carbon tetrachloride is sometimes contaminated with carbon disulfide, which is removed by stirring CCl4 at 60°C in a flask under reflux with 10% (v/v) of a concentrated alcoholic solution of KOH. This procedure is repeated 2-3 times, after which the solvent is washed with water, stirred at room temperature with small portions of conc. H2SO4 until it stops coloring. The solvent is then washed again with water, dried over CaCl2 and distilled over P4O10.

Drying of CCl4 is achieved by azeotropic distillation. The water is removed with the first cloudy portions of the distillate. Once a clear liquid begins to distill, it can be considered anhydrous.

ethyl acetate

Ethyl acetate CH3COOC2H5 is a colorless liquid with a pleasant fruity odor; d20-4 = 0.901; tboil = 77.15°С; n20-D = 1.3728. Forms an azeotropic mixture with water (8.2% (wt.) H2O), tboil = 70.4 °C.

Technical ethyl acetate contains water, acetic acid and ethyl alcohol. Many methods have been proposed for purifying ethyl acetate. One by one, ethyl acetate is shaken with an equal volume of 5% NaHCO3 solution and then with saturated CaCl2 solution. The ethyl acetate is then dried with K2CO3 and distilled on a water bath. For final drying, 5% P4O10 is added to the distillate and shaken vigorously, then filtered and distilled over sodium wire.

Ethanol

Ethyl alcohol С2Н5ОН is a colorless liquid with a characteristic odor; d20-4 = 0.7893; tboil = 78.39 °С; n20-D = 1.3611. Forms an azeotropic mixture with water (4.4% (wt.) H2O). It has a high dissolving power with respect to a wide variety of compounds and is miscible with water and all common organic solvents. Technical alcohol contains impurities, high-quality and quantitative composition which depends on the conditions for obtaining it.

The produced absolute alcohol, which is obtained by azeotropic distillation of 95% industrial alcohol with benzene, may contain small amounts of water and benzene (up to 0.5% (wt.)).

Dehydration of 95% alcohol can be carried out by prolonged boiling with calcined CaO. For 1 liter of alcohol take 250 g of CaO. The mixture is refluxed in a 2-liter flask, closed with a CaO tube, for 6-10 hours. After cooling, the flask is attached to an atmospheric distillation apparatus and the alcohol is distilled off. Yield 99-99.5% alcohol 65-70%.

Barium oxide BaO has higher dehydrating properties. In addition, BaO is able to somewhat dissolve in almost absolute alcohol, turning it yellow. On this basis, it is determined when the process of absolutization is completed.

Further dehydration of 99-99.5% alcohol can be carried out by several methods: using magnesium (ethyl alcohol is obtained with a water content of not more than 0.05%), sodium and oxalic acid diethyl ester.

1 liter is poured into a 1.5-liter round-bottom flask with a reflux condenser and a calcium chloride tube with CaCl2. 99% ethanol, after which 7 g of sodium wire are added in small portions. After dissolution of sodium, 25 g of oxalic acid diethyl ester is added to the mixture, boiled for 2 hours, and the alcohol is distilled off.

Similarly, absolute alcohol is obtained using orthophthalic acid diethyl ester. 1 l of 95% alcohol is placed in a flask equipped with a reflux condenser and a calcium chloride tube with CaCl2, and 7 g of sodium wire are dissolved in it, after which 27.5 g of phthalic acid diethyl ester are added, the mixture is boiled for about 1 hour and the alcohol is distilled off. If not formed in the flask a large number of sediment, this proves that the original alcohol was of fairly good quality. And vice versa, if a large amount of precipitate falls out and boiling is accompanied by shocks, then the initial alcohol was not dried enough.

Drying of ethyl alcohol is currently carried out in column-type apparatuses with NaA zeolite as a packing. Ethyl alcohol containing 4.43% water is fed for drying into a column 18 mm in diameter with a packing bed height of 650 mm at a rate of 175 ml/h. Under these conditions, in one cycle it is possible to obtain 300 ml of alcohol with a water content of not more than 0.1-0.12%. Zeolite regeneration is carried out in a column in a stream of nitrogen at 320 °C for 2 hours. When distilling ethyl alcohol, it is recommended to use devices on thin sections; at the same time, the sections are thoroughly cleaned and not lubricated. It is advisable to discard the first part of the distillate and complete the distillation when a little alcohol remains in the distillation flask.

The invention relates to a method for purifying carbon tetrachloride from impurities of compounds containing carbon-hydrogen bonds and/or double bonds. According to the method, a solution of gaseous chlorine in liquid carbon tetrachloride is exposed to ultraviolet irradiation in a reactor made of a transparent material. EFFECT: purification of carbon tetrachloride from compounds containing double bonds and carbon-hydrogen bonds. The method provides for the production of carbon tetrachloride containing less than 10 mg/ml of compounds with a carbon-hydrogen bond and double bonds. 1 n. and 6 z.p. f-ly, 1 tab.

The invention relates to a method for purifying technical carbon tetrachloride by exhaustive photochemical chlorination of impurities of compounds with hydrocarbon and double bonds with chlorine dissolved in carbon tetrachloride.

Purified carbon tetrachloride can be used by control, analytical and metrological services of chemical, petrochemical and other industries, sanitary and environmental supervision services, for the synthesis of organic compounds, as well as for other purposes.

A known method of purification of carbon tetrachloride from carbon disulfide, characterized in that in order to simplify the technology of the process, the initial carbon tetrachloride is treated with chlorine at a temperature of 10-80°C in the presence of a catalyst with a specific surface area of 10-300 m 2 /g.

The method allows to achieve purification of carbon tetrachloride only from carbon disulfide.

A known method of purification of organochlorine products, in particular methylene chloride, chloroform, carbon tetrachloride and trichlorethylene, from tar and soot. The purification method consists in introducing fuel with boiling ranges from 150 to 500°C into organochlorine products before evaporation or rectification.

The method allows to achieve purification of organochlorine products only from resin and soot.

A known method of purification of technical carbon tetrachloride from non-volatile impurities, based on the rectification separation of liquid mixtures.

The disadvantage of this method is its insufficient efficiency, since only reactive qualification carbon tetrachloride is obtained: "pure", "pure for analysis", "chemically pure", which contains a residual amount of impurities of compounds with hydrocarbon and double bonds, due to their high volatility, proximity boiling points and the formation of azeotropic mixtures with the main component. The carbon tetrachloride obtained in this way cannot be used in the analysis of the content of oil products in water and as a solvent for conducting studies by the method of proton magnetic resonance.

The objective of the invention is to develop an inexpensive and easily feasible method for purifying technical carbon tetrachloride from impurities of compounds with hydrocarbon and double bonds, which makes it possible to obtain carbon tetrachloride for use in the analysis of the content of oil products in water and as a solvent for conducting research using the method of proton magnetic resonance, as well as for other purposes.

The problem is solved by the fact that an easily feasible method for cleaning technical carbon tetrachloride from impurities has been developed, based on the photochemical method of chlorination of compounds with hydrocarbon and double bonds with chlorine dissolved in carbon tetrachloride under the influence of ultraviolet irradiation.

The method is based on the production of highly active chlorine radicals in solution, which are formed by the absorption of ultraviolet light quanta by chlorine molecules dissolved in carbon tetrachloride, which effectively destroy hydrocarbon bonds, leading to the formation of completely chlorinated products as a result of a chain radical reaction. At the same time, processes of complete chlorination of unsaturated compounds take place. Impurities that pollute carbon tetrachloride and do not allow it to be used in many studies, for example, in determining the content of oil products in water, are represented by saturated and unsaturated chlorine derivatives of lower hydrocarbons. These are compounds with hydrocarbon and double bonds, mainly methane derivatives, mainly chloroform, as well as ethane derivatives such as dichloroethane, trichloroethane, trichlorethylene, tetrachlorethylene.

The method of purification of technical carbon tetrachloride from impurities of compounds with hydrocarbon and double bonds is carried out as follows.

Gaseous chlorine is dissolved in carbon tetrachloride until its concentration in the solution is approximately 0.2-2%. The resulting solution is irradiated with mercury-quartz lamps. low pressure. When irradiated in the range of UV radiation 250-400 nm for 1-20 min, impurities of chlorine derivatives of methane are converted into carbon tetrachloride, and chlorine derivatives of ethane - into hexachloroethane. To remove excess chlorine and the resulting acids, carbon tetrachloride after photolysis is treated with a reducing deoxidizer, such as soda ash (Na 2 CO 3). Photochemical chlorination is carried out in a reactor made of a transparent material, mainly quartz glass or Pyrex glass, which transmits UV radiation well in the range of 250-400 nm. Hydrocarbon tetrachloride is obtained containing impurities of compounds with hydrocarbon and double bonds not more than 10 mg/l, determined by the IKN method used to measure the mass concentration of petroleum products in hydrocarbon tetrachloride. Thus purified hydrocarbon tetrachloride contains pentachloroethane and hexachloroethane, while their content depends on the content of ethane chlorine derivatives with hydrocarbon and double bonds in the original technical carbon tetrachloride. Such purified carbon tetrachloride can be used in determining the content of petroleum products in water, since pentachloroethane and hexachloroethane present do not affect the results of the analysis. To obtain high-purity carbon tetrachloride, an additional step is carried out to separate carbon tetrachloride from pentachloroethane and hexachloroethane by conventional distillation, which remain in the distillation residue. The process of photochemical chlorination can be carried out in batch or flow-circulation mode.

Example 1. 0.1 g of chlorine is dissolved in 32 g of technical carbon tetrachloride. The resulting solution in a quartz glass cuvette is irradiated with the light of a DRT-250 mercury lamp for 15 min. After irradiation with UV light, the resulting product was treated with anhydrous sodium carbonate (about 2 g) to remove excess chlorine, resulting acids and water. Based on the chromatographic analysis of the carbon tetrachloride sample before and after purification, it was found that the amount of impurities determined by the SCI method decreased from 217 to 10.2. The mass fraction of pentachloroethane and hexachloroethane was 0.153% and 1.340%, respectively.

Example 2. 0.1 g of chlorine is dissolved in 32 g of technical carbon tetrachloride. The resulting solution in a Pyrex glass cuvette is irradiated with the light of a DRT-1000 mercury lamp for 5 minutes. After irradiation with UV light, the resulting product was treated with anhydrous sodium carbonate (about 2 g) to remove excess chlorine, resulting acids and water. Based on the chromatographic analysis of the carbon tetrachloride sample before and after purification, it was found that the amount of impurities, determined by the IKN method, decreased from 217 to 5.7. The mass fraction of pentachloroethane and hexachloroethane was 0.011% and 1.628%, respectively.

Example 3. Purified carbon tetrachloride, obtained as in example 2, is additionally subjected to distillation at the boiling point of carbon tetrachloride and carbon tetrachloride is obtained in the distillate with a content of the main component of 99.987%, the amount of impurities determined by the SCI method decreased from 5.7 to 2, 3. The VAT residue is a mixture of pentachloroethane and hexachloroethane.

Example 4 Carbon tetrachloride is saturated with chlorine gas to a concentration of 0.6% in a mixer. Then, at a rate of 0.5 l/min, it enters a cylindrical photoreactor made of Pyrex glass, cooled by running water, illuminated by a DRT-1000 mercury lamp located along its axis. From the photoreactor, carbon tetrachloride enters a filter column, where it passes through anhydrous sodium carbonate to remove excess chlorine, as well as the resulting acids and water. Based on the chromatographic analysis of the carbon tetrachloride sample before and after purification, it was found that the amount of impurities determined by the SCI method decreased from 217 to 12.3. The mass fraction of pentachloroethane and hexachloroethane was 0.322% and 1.311%, respectively.

Therefore, when purifying hydrocarbon tetrachloride in this way, carbon tetrachloride is obtained, containing impurities of compounds with hydrocarbon and double bonds, determined by the SCI method, not more than 10 mg/l. The admixture of pentachloroethane and hexachloroethane present in purified carbon tetrachloride makes it possible to use it in determining the content of oil products in water. Further distillation produces "special purity" carbon tetrachloride.

The results of purification of carbon tetrachloride are presented in the table.

Table The content of impurities in carbon tetrachloride
Impurity name, mass fraction (%)*	Impurity content in carbon tetrachloride
	Original	In purified
	Original	Example No.
1	2	3	4
Chloroform	0,240	0,001	0,001	0,001	0,002
Dichloroethane	0,461	0,000	0,000	0,000	0,000
carbon tetrachloride	96,937	97,138	97,170	99,987	97,125
Trichlorethylene	0,477	0,000	0,000	0,000	0,004
Trichloroethane	0,075	0,000	0,000	0,000	0,000
Tetrachloroethane	0,005		0,000	0,000	0,068
Tetrachlorethylene	0,015	0,000	0,000	0,000	0,010
Pentachloroethane	0,000	0,153	0,011	0,005	0,332
Hexachloroethane	0,005	1,340	1,628	0,002	1,311

IKN" (mg/l)	217,4	10,2	5,7	2,3	12,3
* The mass fraction of the component was determined by gas chromatography ** IKN - the total content of the equivalent amount of hydrocarbons was determined by IR spectroscopy on the IKN-025 concentrator

INFORMATION SOURCES

1. SU No. 686274.

2. RU No. 2051887.

3. RU No. 2241513.

4. GOST R51797-2001.

1. A method of purification of carbon tetrachloride, characterized in that the purification of impurities from compounds with hydrocarbon and double bonds is carried out by the method of exhaustive photochemical chlorination with chlorine dissolved in carbon tetrachloride in a reactor made of a transparent material, under the influence of ultraviolet irradiation, while obtaining carbon tetrachloride for analysis determination of the content of oil products in water, containing no more than 10 mg / l of compounds with hydrocarbon and double bonds.

2. The method according to claim 1, characterized in that carbon tetrachloride is obtained for conducting research by the method of proton magnetic resonance.

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