Method for preparing beta-carotene

Abstract

The invention provides a method for preparing beta-carotene. The method comprises the steps of subjecting a vitamin A derivative and triphenylphosphine to a reaction so as to obtain an organic phosphonium salt, and carrying out a coupling reaction in the presence of a palladium compound catalyst and a weak base compound by taking a cyclodextrin compound as a phase transfer catalyst and adopting molecular oxygen as an oxidant, thereby obtaining the beta-carotene. The reaction employs a series method to prepare beta-carotene and is high in reaction selectivity and yield, and the process is simple, so that the method facilitates industrial production.

Description

Technical field [0001] The invention belongs to the technical field of vitamin preparation, and relates to a preparation method of β-carotene, in particular to a method for preparing β-carotene by coupling reaction. Background technique [0002] Beta-carotene is a source of vitamin A, which can be used in medicine, food, cosmetics, feed additives, and dye industries, and has a good market prospect. [0003] There are many methods for the synthesis of β-carotene. The processes for synthesizing β-carotene with vitamin A and its derivatives as starting materials include: [0004] 1. An organic phosphine salt obtained by reacting vitamin A alcohol or its derivative with a triaryl phosphine, which is further condensed with vitamin A aldehyde through Wittig reaction to obtain β-carotene. The French patent Er1383944, the West German patent Gerl148542 and the "Pharmaceutical Industry" Volume 16, Volume 2 reported that the yields were 19.11%, 21.36%, and 26.07%, respectively. In the proces...

AI Technical Summary

Problems solved by technology

[0009] Chinese patents CN101081829A and CN101041631A use hypochlorite to couple to β-carotene under alkaline conditions, but the first two patents are easy to oxidize the product β-carotene due to the strong oxidation of hypochlorite under alkaline conditions. The yield is low; the coupling reaction of the latter patent is a two-phase reaction, the vitamin A triphenylphosphine salt is dissolved in the organic phase, the oxidizing agent and alkali are in the water phase, and the reaction intermediate vitamin A triphenylphosphine ylide Can not be converted into product β-carotene in time, resulting in low yield

This patent can effectively control the solubility of alkali in the organic phase of the reaction, and avoid side reactions such as the self-condensation of VA aldehyde caused by too high alkali concentration and the destruction of the conjugated double bond of the product molecule. Moreover, the post-processing process of this patent is cumbersome, and it takes a long time for isomerization to obtain β-carotene with high purity

[0010] Chinese patent CN108047112A adopts acidic medium oxidant as nitrate, persulfate, peracetic acid, urea peroxide or alkyl hydrogen peroxide to carry out coupling reaction to obtain β-carotene. Has a degradation effect, greatly reducing the yield of the reaction

Images