Process for preparing ascorbic acid ester

Abstract

The invention provides a process for preparing an ascorbic acid ester. Ascorbic acid and fatty acid are used as raw materials. The process comprises the following steps of: cooling the reacted mixture after sulfuric acid catalytic synthesis, adding water into the mixture, extracting the mixture by using mixed solution of aliphatic monoaldehyde and halogenated hydrocarbon, washing the extract by using water, evaporating the extract to obtain a coarse product, re-crystallizing the coarse product by using the halogenated hydrocarbon, and filtering, washing and drying the re-crystallized product to obtain high-purity ascorbic acid-6-fatty acid ester. The process is operated in the same reaction kettle, and the extracting process is in a liquid-liquid form so as to avoid the defects of difficult filtering and drying and difficult moisture removal in the prior art; the extracting solution well dissolves the esterification product and is easily separated from the water, the byproduct is little, and particularly the disadvantages that the purity of a target product is reduced and the quality becomes poor due to emulsification during acid washing in the prior art are avoided; and the coarse product is re-crystallized by using the halogenated hydrocarbon so as to effectively remove a little amount of residual fatty acid which is not totally extracted. The yield of the fatty acid ester product of the ascorbic acid ester produced by the process is over 70 percent, and the purity is over 98 percent.

Description

technical field [0001] The invention relates to a preparation process of ascorbic acid ester, in particular to a preparation process of saturated fatty acid and unsaturated fatty acid ascorbic acid ester. Background technique [0002] There are many methods for synthesizing ascorbic acid fatty acid ester production technology, such as U.S. Patent No. 4,151,178 records: add sulfuric acid, ascorbic acid, and dodecanoic acid in the reaction bottle in turn until all the dodecanoic acid is completely reacted, and the reaction solution is first extracted with a large amount of ether, divided layer, the ether phase was washed with brine, and then the ether was evaporated, and the insoluble solid was repeatedly washed with petroleum ether, and dried in vacuo to obtain the product. Recrystallization is carried out with diethyl ether and petroleum ether. In this method, a large amount of volatile, inflammable and explosive diethyl ether needs to be used, and the crude product is repea...

AI Technical Summary

Problems solved by technology

The disadvantages of this method are firstly that the feed liquid is a viscous liquid, which is not easy to remove, and the loss is large, it is difficult to wash the filter cake with water, it is difficult to filter, and it is easy to emulsify, it is difficult to dry after acid washing, and the water is not easy to remove

[0004] Chinese patent CN 1,478,775A records: add ascorbic acid into the reaction bottle of tetrahydrofuran and water, drop into isopalmitoyl chloride and sodium hydroxide solution, keep the pH value of 6-8 in the reaction, after the reaction, add ethyl acetate to stir and extract the reactant, This method needs to keep the pH of the reaction solution at 6-8. When the pH value of the reaction solution is lower than 6, ethyl acetate is added, and the organic phase and the water phase are not easy to separate, resulting in greater product loss and impurities in the water phase. removal, leading to a decrease in product purity

This method is more complicated, and repeated operations will reduce the product yield. A large amount of diethyl ketone is used, and the production cost is high. Diethyl ketone and water are very miscible. Simply using this solvent for extraction will easily lead to solvent and viscous mixture. Miscible, not easy to separate, resulting in a decrease in yield

In addition, acid is artificially added during the isomerization process, which increases the difficulty of post-processing

The target product and palmitic acid are easily soluble in diethyl ketone, so it is not easy to separate in the end