Preparation method of pseudoionone

Abstract

The invention provides a preparation method of a vitamin A intermediate pseudoionone. The method relates to a reaction for preparing pseudoionone by catalyzing condensation of acetone and citral by using a novel catalyst, the use amount of reaction acetone can be effectively reduced by using the novel catalyst, self-polymerization and copolymerization of citral and pseudoionone in the reaction arereduced, and the reaction selectivity and yield are improved.

Description

technical field [0001] The invention belongs to the field of synthesis of chemical intermediates, and in particular relates to a preparation method of a heterogeneous catalyst and a method for preparing pseudoionone by condensation of acetone and citral catalyzed by the catalyst. Background technique [0002] Pseudoionone, that is, 6,10-dimethyl-3,5,9-undecatrien-2-one, is an important synthetic flavor and fragrance α- and β-ionone and vitamin A, E, etc. Important intermediates of pharmaceutical and chemical products. The general method for industrial production of ionone is to make ketone-aldehyde condensation reaction between citral (Citral) and acetone (Acetone) in NaOH aqueous solution to generate pseudo-ionone. One molecule of citral and one molecule of acetone undergo a Claisen-Schmidt ketoaldehyde condensation reaction under alkaline conditions to generate a molecule of pseudoionone and a molecule of water. The activation energy of most ketone-aldehyde condensation ...

AI Technical Summary

Problems solved by technology

The activation energy of most ketone-aldehyde condensation reactions is low, so there are many side reactions in the process, the selectivity is poor, and the product purification is difficult

[0003] The catalyzer that is used for condensation reaction of acetone and citral with regard to the literature of report at present relates to is a lot, mainly is divided into two classes, and a class is homogeneous catalyst, as: sodium hydroxide, potassium hydroxide, primary amine, secondary amine etc., This type of catalyst can be dissolved in the reaction system and can complete the condensation reaction in a short time, but the degree of reaction is uncontrollable. During the reaction, a large number of self-polymerization and copolymerization reactions between citral and pseudoionone occur, and the reaction selectivity is poor. The reaction yield is less than 80%; the other type is heterogeneous catalyst, which uses a variety of supports, such as molecular sieves, activated carbon, basic Al 2 o 3 and ZrO 2 , supporting alkaline hydroxides in it, such as NaOH, LiOH, etc. This type of catalyst prolongs the reaction time and appropriately improves the reaction selectivity, but it is also unavoidable to avoid a large amount of side reactions, and the amount of acetone used in this type of process system is large increase, the reaction selectivity is generally 80-90%

[0004] All there is corresponding defective in above-mentioned each method, there are various problems when being used for industrial scale-up, as the consumption of acetone is too large, industrial scale-up is difficult, reaction selectivity is low, product purity is low etc.