Continuous process for the manufacture of 3,5,5-trimethylcyclohexa-3-en-1-one (b-isophorone)

Abstract

For the continuous manufacture of &bgr;-isophorone by isomerization under homogeneous catalysis of &agr;-isophorone, the steps of introducing the &agr;-isophorone and a solution of an alkaline hydroxide into a reaction region, bringing the reaction mixture to reflux at a temperature at least equal to 150° C. under a equal P1 of less than or equal to atmospheric pressure, continuously and simultaneously removing from the reaction mixture: &bgr;-isophorone vapor, by distillation under a pressure P2 less than P1 and at a temperature at most equal to 150° C., and heavy products, at a rate, so that their content by weight is at most equal to 7% in the reaction mixture, and continuous returning the distillation to the reaction region.