SU1498756A1 - Method of separating dimethylsulfoxylic acid from aqueous solutions - Google Patents

Abstract

The invention relates to unsaturated nitriles, in particular, the preparation of cyclohexenylacetonitriles, intermediates for the synthesis of biologically active substances. The process is carried out by the reaction of cyclohexanone with an excess of acetonitrile at 280-300 ° C in the presence of a catalyst - potassium hydroxide or cesium, deposited on AL ₂ O ₃ . It is advisable to use a 4-5-fold molar excess of acetonitrile and a catalyst containing 30-35 wt.% Alkali metal hydroxide. These conditions increase the yield of the desired product from 41 to 70.6 - 78.2% and the selectivity of the process from 41 to 97.8%. 1 hp f-ly, 1 tab.

Description

The invention relates to an improved process for the preparation of cyclohexenyl acetonitrile, which finds use as an intermediate for the synthesis of phenylacetic acid nitrile, the derivatives of which are biologically active substances.

The purpose of the invention is to increase the selectivity and yield of the target product.

Example 1. Preparation of the catalyst.

The catalyst is prepared by depositing calculated amounts of aqueous solutions of potassium or cesium hydroxides on previously calcined alumina. After impregnating the alumina, the solution is evaporated. The catalyst is dried and calcined.

The preparation of a catalyst containing 35% by weight of KOH / A1 0 is carried out as follows. 7.7 g of potassium hydroxide are dissolved in 25 ml of water. : The resulting solution is poured 22 g of calcined alumina. And evaporated with stirring. The resulting catalyst is dried and calcined. Immediately before the experiment at 300– for 1 hour. A catalyst is obtained containing 35% by weight of KOH / Al O. Similarly, the catalysts used in the proposed method are prepared.

Example 2. In a quartz reactor with a diameter of 20 mm load 25 cm of catalyst containing 35 wt.% Potassium hydroxide on aluminum oxide. The catalyst is calcined in the reactor at 300-320 C for 1 hour. Then, at

four

00

 ate

with:

 . The catalyst serves 26.2 g of a mixture containing 9.8 g (0.1 mol) of cyclohexanone and 16.4 g (0.4 mol) of acetonitrile. The volumetric feed rate of the mixture is 0.2 h. The catalyst is subjected to vacuum distillation. 9.07 g of cyclohexenyl acetonitrile are introduced, which is 75.1% (from theory). The conversion of cyclohexanone is 77.0%, the selectivity of the process is 97.5%. The selected product is characterized by the following constants:

m.p.

73 -, go

 mmHg.; 1.4769; d 0.9242.

Found,%: C, 79.30; H 9.21; N 11.50.

Calculated,%:, 34; H 9.08; N 11.57.

EXAMPLE 3: The experiment was carried out as described in Example 2, but 35% by weight of cesium hydroxide on alumina was used as catalyst. 9.48 cyclohexenenylacetonitrile was isolated by vacuum distillation, which is 78.4% of theory. The conversion of cyclohexanone is 80.0% with a process selectivity of 98%.

Examples 4-21. The experiments were carried out according to the method of example 2.

The results are presented in the table.

Thus, the proposed method allows to increase the yield of the target product from 41% in the known method to 70.6-78.2% and increase the selectivity of the process for the target product from 41 to 97.8%.

Claims (2)

1. A method of producing cyclohexenip-acetonitrile by reacting cyclohexamone with an excess of acetonitrile at an elevated temperature in the presence of an alkali metal hydroxide catalyst, characterized in that, to increase the yield of the target product and increase the selectivity of the process, potassium hydroxide or cesium deposited on the oxide, and the process is carried out at 280-300 C. 2. Method POP.1, characterized by the fact that the process is carried out at a molar ratio of cyclohexanone: acetonitrile 1: 4-5 and a catalyst containing 30–35% by weight of the alkali metal hydroxide.