SU1377274A1 - Method of producing 1-methyl-1-phenylcyclohexane - Google Patents

Abstract

The invention relates to the production of hydrocarbons, in particular the preparation of 1-methyl-1-phenylcyclohexane, used as a heat carrier. In order to increase the yield of the target product, alkylation of benzene with Z-methipcyclohexanol in the presence of 96% sulfuric acid

Description

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The invention relates to the synthesis of alkyl aromatic hydrocarbons, and specifically to a method for producing 1-methyl-1 phenylcyclohexane, used as a heat carrier in industry.

The aim of the invention is to increase the yield of the target product.

When benzene interacts with methylcyclohexanols in the presence of a catalyst of 96% sulfuric acid, in addition to the alkylation reaction, the polymerization products of the conversion of the starting alcohol react with the formation of dicyclohexyls and other hydrocarbons, which leads to a decrease in the yield of the desired product and deactivation of the catalyst. When nitromethane is introduced into the reaction mixture, there is practically no polymerization and the alcohol participates in the formation of 1-methyl-1-phenylcyclohexane with 100% selectivity. The reaction under the conditions of the process in the molecular molecule of hydride transfers with the formation of the most stable 1-methyl cyclohexyl cation allows the use of the most cheap 3-methyl cyclghexanol as compared to other alkylating agents.

The proposed molar ratio of benzene - nitromethane - 96% sulfuric acid - 3-methylcyclohexanol is optimal.

When the ratio is less than 20: 20: 10: 1, both the yield of monocycloalkylbenzenes and the selectivity of the 1,1-isomer decrease, since the amount of nitromethane is not enough to slow down the polymerization reaction.

A further increase in the concentration of CHoNO and benzene above the molar ratio of 25: 25: 10: 1 does not lead to an increase in the yield of monocycloalkyl benzenes and is associated with an additional consumption of nitromethane solvent, which is not economically feasible.

With a process duration of less than 20 minutes, the conversion of 3-methylcyclohexanol decreases and the yield of catalysis is due to the fact that the alcohol does not have time to react. If the process lasts more than 30 minutes, the yield and selectivity of the 1,1-isomer decrease, since oxidation and sulfonation reactions occur in parallel.

The method is carried out as follows.

The alkylation process is carried out in a reaction flask in which benzene, solvent (nitromethane), 96% sulfuric acid and 3-methylcyclohexanol are placed at a molar ratio of 25: 25: 10: 1, respectively. The reaction time is 20 minutes, the temperature is 20 C. The yield of 1-methyl-1-phenylcyclohexane is 99.1 wt.%.

In tab. Table 1 gives examples showing the optimality of the molar ratio of benzene - nitromethane - 96% - for sulfuric acid - 3-methylcyclohexanol.

In tab. 2 presents examples proving the optimality of the time t of the process.

As can be seen from the table. 1 and 2, the proposed method provides the yield of the target product to 99.4% with an alcohol conversion of 100%.

Claims (1)

Invention Formula The method of producing 1-methyl-1-phenyl-cyclohexane by alkylation of benzene with 3-methylcyclohexanol in the presence of concentrated sulfuric acid at room temperature for 20-30 minutes, characterized in that, in order to increase the yield of the target product, alkylation is carried out in nitromethane at mol The ratio between benzene and nitromethane is 3-methylcyclohexanol 20-25: 20-25: 1. Table 1 3-Methylcyclo 30 28.1 hexanol 3-methylcyclo 30 80.9 hexanol 100.0 100.0 table 2