Studies on Nitroparaffins. VIII

Preparation of 4-ketocaproic acid from 1-nitropropane

Abstract

Reaction of 1-nitropropane and ethyl acrylate in 3:1 molar ratio in the presence of basic condensation agent was proceeded easily with Michael condensation reaction and gave ethyl 4-nitrocaproate. Caustic alakali, carbonate of alkali, sodium bicarbonate, sodium amide, and sodium methylate, etc., were used as the condensation agents, among which sodium hydroxide gave the best result and the objective substance was obtained in 67.6% yield by heating for 5 hrs at 40-45°C.
Saponification of the ethyl 4-nitrocaproate with sodium hydroxide solution and application of so-called Nef reaction of using dilute sulfuric acid on an intermediate acid-type salt gave a transition into corresponding 4-ketocaproic acid. The effects of reaction temperature, amount and concentration of sulfuric acid have been investigated. It was indicated that the reaction with dilute sulfuric acid (1: 4.4) at 3-5°C yielded 74.2% 4-ketocaproic acid.