Preparation method of 1,4-cyclohexanedione monoketal

Abstract

The invention relates to a preparation method of 1,4-cyclohexanedione monoketal, which comprises the following steps: adding cyclohexanedione into an acidic reaction liquid of tetrahydrofuran in a reaction kettle, and stirring until cyclohexanedione is completely dissolved; adding ethylene glycol and a catalyst into the reaction system, and stirring and heating to react; extracting: cooling afterthe reaction is finished, adding a reaction solution into the reaction system, extracting in batches by utilizing methylbenzene, and mixing extracted organic phases; adding a 10% sodium chloride solution into the extracted organic phase, washing, and distilling to remove methylbenzene after washing is finished; and crystallizing: adding a mixed solution of ethyl acetate and cyclohexane into the organic phase from which methylbenzene is removed, and crystallizing to obtain 1,4-cyclohexanedione monoketal. The organic acid is used as a catalyst, so that the yield of monoketal is increased; and the mixed solvent is used for crystallization and purification, cyclohexanedione and cyclohexanedione diketal in the product are crystallized at a time, and product loss caused by multiple times of crystallization is avoided.

Description

technical field [0001] The invention relates to a preparation method of 1,4-cyclohexanedione monoketal, which belongs to the technical field of chemical synthesis. Background technique [0002] 1,4-cyclohexanedione monoketal generally exists in two types: 1,4-cyclohexanedione monoethylene glycol ketal and 1,4-cyclohexanedione mononeopentyl glycol ketal, which are mainly used for light and thin High-grade liquid crystal display materials and synthetic intermediates of pesticides. The synthetic raw material of 1,4-cyclohexanedione monoketal is generally obtained by condensation of 1,4-cyclohexanedione and ethylene glycol or neopentyl glycol as raw materials under acid-catalyzed dehydration conditions. The commonly used catalysts are strong protonic acids (such as sulfuric acid, hydrochloric acid, phosphoric acid, etc.), and there are many by-products, which will produce a large amount of bisketal products. And the purification method of existing 1,4-cyclohexanedione monoketa...

AI Technical Summary

Problems solved by technology

Commonly used catalysts are strong protic acids (such as sulfuric acid, hydrochloric acid, phosphoric acid, etc.), there are many by-products, and a large amount of bisketal products will be produced

And the purification method of existing 1,4-cyclohexanedione monoketal mainly utilizes organic solvent to cyclohexanedione monoketal and bisketal mixture recrystallization, because cyclohexanedione monoketal and bisketal The polarity of the ketal is not much different, and repeated recrystallization is required to obtain a high-purity monoketal product. During the multiple recrystallization process, multiple freezing and filtration are required, and the product loss is large.