Continuous process for the manufacture of 3,5,5-trimethylcyclohexa-3-en-1-one (B-isophorone)
AssigneeAtofina
InventorsFrancois Mongenet, Rémy Teissier
Life of this patent
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Abstract
For the continuous manufacture of β-isophorone by isomerization under homogeneous catalysis of α-isophorone, the steps of introducing the α-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: β-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.
Claims21
A continuous process for the manufacture of 3,5,5-trimethylcyclohexa-3-en-1-one (β-isophorone) by isomerization under homogeneous catalysis of 3,5,5-trimethylcyclohexa-2-en-1-one (α-isophorone), obtained by trimerization of acetone in alkaline medium, the said process being characterized in that the following stages are carried out:
- a) α-isophorone and a solution of an alkaline hydroxide are continuously introduced into a reaction region,
- b) the reaction mixture is brought to reflux at a temperature at least equal to 150° C. and under a pressure P1 of less than or equal to atmospheric pressure,
- c) the following are continuously and simultaneously removed from the reaction mixture:
- 1) the β-isophorone of the vapour phase, by distillation under a pressure P2 which is less than P1 and at a temperature at most equal to 150° C.,
- 2) heavy products, by drawing off, so that their content by weight is at most equal to 7% in the reaction mixture, and
- d) the distillation condensates are continuously returned to the reaction region.
A continuous process for the manufacture of 3,5,5-trimethylcyclohexa-3-en-one (β-isophorone) by isomelization under homogeneous catalysis of 3,5,5-trimethylcyclohexa-2-en-1-one (α-isophorone), obtained by trimerization of acetone in alkaline medium, said process comprising:
- (a) continuously introducing α-isophorone and a solution of an alkaline hydroxide into a reaction region,
- (b) bringing the resultant reaction mixture to reflux at a temperature of at least 150° C. and under a pressure P1 of not more than atmospheric pressure,
- (c) continuously and simultaneously removing from the resultant refluxed reaction mixture:
- (1) a gaseous mixture of β-isophorone and α-isophorone, and
- (2) heavy products at a rate sufficient to maintain the concentration of said heavy products in the reaction mixture at not more than 7% by weight, and
- (d) passing said gaseous mixture of α-isophorone and β-isophorone through a pressure-reduction device and then into a bottom section of a single distillation column, maintaining a sufficient reflux ratio in said distillation column so as to obtain a desired purity of β-isophorone at a top section of said column, and
- (e) withdrawing liquid condensate from the bottom of said distillation column and recycling said liquid to the reaction region, said distillation column being operated under a pressure P2 which is less than P1 and at a temperature at most equal to 150° C.
Dependencies are inferred from the claim text.