Preparation method for dl-alpha tocopheryl acetate

Abstract

The invention relates to a preparation method for dl-alpha tocopheryl acetate. The preparation method uses trimethylhydroquinone-1-ethyl ester as a raw material and a Bronsted acid and a Lewis acid ascatalysts, the trimethylhydroquinone-1-ethyl ester and phytol or isophytol or a phytol derivative are directly subjected to a condensation reaction in an ester solvent, and therefore the product dl-alpha tocopherol acetate is directly obtained. The method provided by the invention has a relatively simple process route and reduces production costs, and the obtained product has better quality and ahigher yield, and is suitable for large-scale industrialized production.

Description

technical field [0001] The invention relates to a method for directly preparing dl-alpha tocopheryl acetate by using trimethylhydroquinone-1-ethyl ester as a raw material for condensation reaction. Background technique [0002] As a kind of trace organic matter necessary to maintain human life activities, vitamin E mainly has the functions of anti-oxidation, anti-aging, improving immunity, and anti-infertility. It was mainly used in clinical infertility and reproductive promotion treatment in the early days. It is more used for beauty and anti-aging, anti-free radical oxidation, protection of red blood cells, protection of T lymphocytes, improvement of blood circulation, inhibition of platelet aggregation, treatment of menopausal syndrome and treatment of burns and frostbite, etc. The actual products are mainly used in medicines, food , cosmetics and feed additives. [0003] Vitamin E mainly includes natural vitamin E and synthetic vitamin E, of which synthetic vitamin E ma...

AI Technical Summary

Problems solved by technology

[0008] These reactions as mentioned above have the following defects: 1) the synthesis of raw material trimethylhydroquinone is more complicated than trimethylhydroquinone monoester or trimethylhydroquinone diester, and the cost is higher; 2) raw material trimethylhydroquinone Unstable, easily oxidized, and difficult to store; 3) The raw material trimethylhydroquinone has a certain degree of toxicity, exists in the state of light solid powder, and is easy to float in the air or adsorb on the human body, which is harmful to human skin, respiratory tract, etc. Produce greater irritation, thereby bringing certain environmental impact and occupational disease risk in actual production; 4) The dl-alpha tocopherol obtained by the reaction is easily oxidized, and generally needs to be esterified to obtain dl-alpha tocopheryl acetate, The process is more complicated, and at the same time, the esterification reaction must consume a certain amount of acetic acid or acetic anhydride and energy, etc.

[0011] EP02025989 patent states that trimethylhydroquinone-4-ethyl ester is reacted with isophytol or phytol, the solvent is an aprotic organic solvent, and the catalyst only uses a sulfonic acid catalyst or a basic catalyst to obtain dl-α tocopherol Or the mixture of dl-alpha tocopherol and dl-alpha tocopheryl acetate, and then through the esterification mode, finally obtains dl-alpha tocopheryl acetate, this invention has certain limitations, simultaneously in sulfonic acid catalyst or alkaline In the catalyst, the condensation reaction is also more difficult, resulting in a lower product yield, the yield is 10.2-81.9%

[0012] Patent EP03000493 / EP03024288 uses a special catalyst to catalyze the reaction of trimethylhydroquinone-4-ethyl ester with phytol, isophytol or (iso)phytol derivatives to obtain dl-α tocopheryl acetate, in which the catalyst is made of noble metal or rare earth Metal compounds, resulting in high process cost, high reaction temperature, and slightly complicated process

[0013] EP04013713 patent also uses trimethylhydroquinone-4-ester (including esters such as ethyl ester and propyl ester) to react with isophytol, phytol or (iso)phytol derivatives, and the catalyst is a salt compound containing rare metals , the condensation reaction is required to be carried out under a certain pressure, the reaction conditions are more complex, and the selection of catalysts leads to higher process costs

[0014] In the DE10011402 patent, it is mentioned that directly use trimethylhydroquinone diethyl ester to react with isophytol, and use a polar solvent (such as acetic acid) as the reaction medium. This method mainly utilizes the polar solvent acetic acid to dissolve the catalyst so as to facilitate subsequent recovery and mechanical application, and Solvents such as acetic acid are not easy to decompose, and the loss is small, but trimethylhydroquinone diethyl ester is not easy to remove the ethyl carboxyl group in polar solvents such as acetic acid, thereby hindering the formation of the product dl-α tocopherol or dl-α by cyclization with isophytol Tocopherol acetate, resulting in low process yield, and because it is difficult to separate acetic acid and water in the industry, the water content in the mechanically applied catalyst will continue to accumulate, resulting in the failure of the late catalyst and the inability to catalyze the condensation reaction

[0015] EP01104141.5 patent uses appropriate biological esterase to convert trimethylhydroquinone diethyl ester into trimethylhydroquinone monoester, and then purifies and then performs subsequent corresponding F-C reaction condensation to obtain dl-α tocopheryl acetate. The requirements for enzymatic hydrolysis and separation process conditions are relatively high, and the process route is relatively complicated

[0016] CN201110198791 uses a one-pot method to react trimethylhydroquinone diethyl ester with isophytol. The process first uses lower aliphatic alcohols to carry out transesterification reaction with trimethylhydroquinone diethyl ester under acid catalysis to obtain trimethylhydroquinone , then reclaim the lower fatty alcohol and the lower fatty acid ester of acetic acid to obtain the trimethylhydroquinone solid, and then carry out the subsequent condensation reaction and esterification reaction to obtain dl-α tocopheryl acetate. There are certain defects in this method: recovery In the process of lower fatty alcohols and fatty acid esters, trimethylhydroquinone is easily oxidized; in the process of reclaiming lower fatty alcohols and esters, trimethylhydroquinone is solid, which is difficult to realize in actual industrial production; the transesterification reaction is difficult to complete, resulting in the final Low product yield, poor product quality, etc.

[0017] The literature technologies disclosed above all have certain defects. Among them, some synthesis processes are relatively complicated and costly. Some processes obtain poor product quality and low yield. Some processes also have relatively high process conditions. Large-scale production has certain advantages. limitations, etc.

Images