RU2076855C1 - Process for simultaneously preparing chloroform and aromatic hydrocarbon chlorinated into side chain - Google Patents

Abstract

FIELD: organochlorine syntheses, more specifically preparation of chloroform and hydrocarbon chlorinated into side chain. SUBSTANCE: is reacted with aromatic hydrocarbon in liquid phase at elevated temperature (160-190 C) for 8-20 hours in the presence of copper (I) chloride complexes with tertiary amine of formula: R₃N wherein R is C₂-C₅-alkyl or copper sulfide of formula:

wherein R′ = C₁-C₉-alkyl, copper chloride to amine or sulfide molar ratio being 1:1-5. In the preferred process embodiment said complex is applied onto mineral carrier in amount wherein copper chloride to carrier weight ratio is 1:4-100. The claimed process for simultaneously preparing chloroform and aromatic hydrocarbons chlorinated into side chain makes it possible to reduce process duration by 3-5 times, increase process selectivity up to 94-100% and reduce process temperature to 160-190 C. EFFECT: more efficient preparation process. 2 cl, 1 tbl

Description

 The invention relates to organochlorine synthesis, specifically to the production of chloroform and aromatic hydrocarbons chlorinated in the side chain.

Currently, a wide range of methods have been developed for producing alkyl aromatic hydrocarbons chlorinated in the side chain. A typical example is the process of producing benzyl chloride from toluene by chlorination with molecular chlorine at 60-70 ^o C in the presence of radical reaction initiators [1] The method is used in industry, however, has a number of disadvantages. In particular, it is not possible to avoid the formation of significant quantities of byproducts of benzene chloride, ortho- and parachlortoluenes. Separating the latter from the target product is a complex technological challenge. Another significant drawback of this and similar processes is the need for thorough purification of raw materials from iron ions and other impurities, which complicates and increases the cost of technology.

A known method of producing chloroform, according to [2] according to which a mixture of methyl chloride and methylene chloride is chlorinated with molecular chlorine with a ratio of chlorine to mixture of 0.5 0.7: 1 and a temperature of 400 to 500 ^o C in a fluidized bed of electrocorundum. The chloroform selectivity is less than 94%. The technology is quite complicated due to the use of high temperatures and the need for strictly controlling the composition of the reaction mass, as well as the use of a valuable methylene chloride product as one of the components of the feed.

In view of the signing of the Montreal Convention and the related ban on the production of C ₁ freons in Russia and abroad, a large excess of carbon tetrachloride (CFC) has arisen during the chlorinolysis of organochlorine wastes. The challenge is the qualified processing of CFCs, and the most rational is its use in the production of chloroform.

Closest to the proposed is a method for the simultaneous production of chloroform and aromatic hydrocarbons chlorinated into the side chain (ethylbenzene, cumene, etc.) by heating them with CFC in the dark at 220 - 225 ^o C or under the influence (under the conditions of boiling of the reaction mass) of light [3] The process solves the problem of the qualified use of CFC with the simultaneous production of chloroform and chlorinated aromatic hydrocarbon. However, the process has a number of significant drawbacks of low selectivity (<10%) (hydrogen chloride, dicumyl, and condensation products are formed, in addition to the target product) and a long duration of 58 hours, even when irradiated with UV light.

, где R' C₁ C₉-алкил, причем мольное соотношение хлорида меди к амину или сульфиду составляет 1:1 5.The present invention solves the problem of simultaneous production of chloroform and aromatic hydrocarbon chlorinated in the side chain while reducing process time, increasing selectivity, lowering temperature. The solution of this problem is achieved by the interaction of CFC with an aromatic hydrocarbon in the liquid phase at elevated (160 180 ^o C) temperature in the presence of complexes of copper (I) chloride with a tertiary amine of the formula R ₃ N, where RC ₂ C _{5 is} alkyl, or a sulfide of the formula

where R 'C ₁ C ₉ -alkyl, and the molar ratio of copper chloride to amine or sulfide is 1: 1 5.

 In a preferred embodiment of the method, the above complex is applied to the mineral carrier in an amount corresponding to a weight ratio of copper chloride to carrier of 1: 4 to 100.

A distinctive feature of the invention is the use of the catalyst of the above composition. This catalyst allows to reduce the duration of the process to 8-20 hours, lower the temperature to 160 190 ^o C and increase the selectivity: the monochloro derivative of an aromatic hydrocarbon with chlorine in the side chain is almost the only chlorination product, hydrogen chloride is formed in trace amounts, the output of products other than chloroform C ₁ , insignificant, does not exceed 5%
The preparation of a homogeneous catalyst is carried out by simple dosing of its components into the reaction mass, the preparation of the supported catalyst is illustrated by example 1. The invention is illustrated by examples 2 to 14.

Example 1. 14.6 g (0.1 mol) of liquid dibutyl sulfide are dissolved in 500 ml of chloroform. 10 g of monovalent copper chloride are added to the resulting liquid mass with continuous stirring and stirring is continued at room temperature for 1 hour. Then, 100 g of KSK silica gel is added to the resulting homogeneous solution and stirring is continued for 6 hours. After this, the catalyst support is separated from the liquid washed with dry ether and dried in a stream of dry air for 4 hours at room temperature and an additional 2 hours at 100 ^o C. Get friable greenish powder, which is used in catalysis.

Example 2. In the reaction vessel of thick-walled glass with a volume of 30 ml contribute 15.3 g (0.1 mol) of carbon tetrachloride and 1.8 g (0.02 mol) of toluene, then add 0.5 g of monovalent copper chloride and 1, 46 g of dibutyl sulfide (molar ratio 1: 2). The reactor is sealed, heated to 160 ^o C and maintained at this temperature for 18 hours. Then the reactor is cooled to room temperature and then, using a mixture of dry ice acetone, up to 70 ^o and open, and the contents are analyzed by GLC. The following results are obtained: toluene conversion 30% carbon tetrachloride (CFC) 6% selectivity for the formation of benzyl chloride from toluene 100% (no other products within the experimental error), selectivity for chloroform 96% methylene chloride and hexachloroethane are formed with a total yield of 4% based on the reacted CHU. Hydrogen chloride is absent.

 In examples 3 to 16, the process is carried out similarly. In the examples with a heterogeneous (supported) catalyst, a measured amount of the catalyst is introduced into the reaction mass, after which it is shaken vigorously to ensure initial contact of the reactants with the catalyst. When working with a heterogeneous catalyst, the contents of the reactor are stirred every 0.5 hours during the entire experiment.

 The conditions and results of the examples are shown in the table.

 The examples given in the table show that the method of simultaneous production of chloroform and aromatic hydrocarbons chlorinated in a chain can significantly reduce the duration of the process while increasing its selectivity. Comparative examples 15, 16 for conducting the process outside the selected intervals of the conditions confirm the validity of this choice.

Claims (2)

1. The method of simultaneous production of chloroform and an aromatic hydrocarbon chlorinated in the side chain by reacting the corresponding aromatic hydrocarbon with carbon tetrachloride in the liquid phase at elevated temperature, characterized in that the process is carried out in the presence of a complex of copper (I) chloride with an amine of the formula R ₃ N,
where RC ₂ C ₅ -alkyl, or sulfide of the formula R $\genfrac{}{}{0ex}{}{\text{one}}{\text{2}}$ S
where R 'C ₁ C ₉ -alkyl,
moreover, the molar ratio of copper chloride to amine or sulfide is 1 1 5.  2. The method according to p. 1, characterized in that they use a catalyst supported on a mineral carrier in an amount corresponding to the mass ratio of copper chloride and carrier 1 4 100.

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