SU721385A1 - Method of preparing 1,3,5-hexatriene - Google Patents

Description

The invention relates to petrochemical synthesis and can be used to produce hexatrienes, specifically 1,3,5-hexatriene.

A known method for producing 1,3,5-hexatriene by splitting 2-methyl-5, b-dihydro-2 (H) -pyran in an environment with a pH of 6.7-5.0 on acidic and inert catalysts, at 300-400 ° C , volumetric feed rate 0.4-1 h, pressure 4q, -700 mm Hg, the ratio of pyran to water 1: 1.5-1: 5 by weight {. The disadvantage of this method is a relatively low yield of the target product (76.6%),

The closest to the present method is the method of obtaining 1,3,5-hexatriene by cleaving 4-prspenil-1, 3-dioxane in a medium with a pH of 6.7-5 in the presence of inert and acidic catalysts with a function of Hammett acidity from inert to +1.5 at 360-380 ° С, weight feed rate of the raw material 0.5-0.8, pressure 50-500 mm Hg., Dilution of the raw material with water vapor from 1: 1.5 to 1: 5 2. The yield of the target product is 70%. The disadvantage of this method is relatively low yield, catalyst coking ability, the need to maintain the discharge in the reaction zone, the frequency of the process.

The aim of the invention is to increase the yield of 1,3,5-hexatriene and simplify the process.

This goal is achieved by the method of obtaining 1,3,5-hexatriene by dihydration of 4-hexene-1,3-diol in the presence of inert and acidic catalysts with an acidity function.

Hammett from inert to +1.5 at 200300 ° С and dilution of raw materials with water vapor.

It is preferable to carry out the process at a weighted feed rate.

0.42-1.5 times the dilution with water vapor in the ratio of 1: (1-5).

Various industrial catalysts are used as catalysts - silica gel, calcium phosphate catalysts (KDV-15y, KF-70), alumina, aluminosilicates, phosphoric acid on kieselguhr and others.

The method allows to reduce the temperature in the reaction zone as compared to

in a known manner at 100-140 s.

 The service of the catalyst reaches several months, while in the case of the dehydration of dioxanes, 2-4 hours, after which its regeneration is necessary.

Example. The process of obtaining 1,3,5-hexatriene is carried out in a continuous flow system consisting of a tubular quartz reactor filled with glass beads in the upper part, which serves as an evaporator and a superheater, and in the lower part of the catalyst, 450 mm long and 22 mm in diameter. placed in an electric furnace, micro-dosing pumps in a food receiving system consisting of a refrigerator and a receiver cooled by a mixture of ice and salt, supply lines,

4-Hexane-1, W-diol and water are fed to the evaporator - superheater. Couples brought to the temperature of experience, in contact with a layer of catalyst. Next, the contact gas flows through the refrigerator to the receiver. The organic part of the catalyst is separated from the water and by a single evaporation from it a fraction is obtained up to 100 ° C, which is dried. After adding hydroquinone (to prevent polymerization) (0.5 + 1.5%), the fraction is subjected to distillation (cht 18-20) and 1,3,5-hexatriene is isolated at 80 ° C with bp. 80 ° C; n ° 1.5080; ° 0.791 MRD. Found 29, 77, Calculated 28.51.

Found,%: C 90.31; H 10.20.

Calculated,%: C, 89.940; H 10.06.

Table 1 shows the starting and prepared compounds, which are isolated and identified in the usual way, and their constants.

Table 2 summarizes the conditions and results of the process in accordance with the method.

Table 1

Claims (2)

1. Method of producing 1,3,5-gbxatriene by treating the burner in the presence of inert and acidic catalysts with the function of the Hammett acidity from inert to +1.5 at extended temperature and dilution of the raw material with water vapor, characterized by that. that, in order to increase product yield and simplify the process, 4-hexene-1,3-diol is used as a raw material and the process is carried out at 200300 C. 2. The method according to claim 1, characterized in that the process is carried out 6 at a weight feed rate of raw materials of 0.42-1.5 and dilution with water vapor in the ratio of 1: (1-5). Sources of information taken into account in the examination 1. USSR author's certificate No. 551316, cl. From 07 C. 11/21, published in 1977. 2. USSR author's certificate according to application no. 1971440 / 23-04, cl. C 07 C 11/21, C 07 C 1/20, 1973, according to which a positive decision was made (prototype).