Synthetic method of p-hydroxyacetophenone

Abstract

The invention mainly discloses a synthetic method of p-hydroxyacetophenone. According to the synthetic method, phenol and acetic anhydride are taken as raw materials so prepare phenylacetate; under catalytic action of aluminium trichloride, o-dichlorobenzene is added for reaction, steam distillation is carried out, active carbon filtration is carried out, and crystallization is carried out so as to obtain p-hydroxyacetophenone; and then p-hydroxyacetophenone is also prepared via two times of circular reaction of o-dichlorobenzene layer and phenylacetate, wherein the o-dichlorobenzene layer contains o-hydroxyacetophenone and is obtained via layering of a product of the former reaction. Compared with the prior art, the synthetic method possesses following advantages: side product suppression assistant circulating method (three times of continuous operation, and two times of circulation) is adopted, o-dichlorobenzene containing o-hydroxyacetophenone is used in circulation process, generation of o-hydroxyacetophenone in subsequent process is reduced effectively, p-hydroxyacetophenone yield is increased by 10% at least, and HPLC detection purity is 99.7% or higher. The synthetic method is capable of increasing p-hydroxyacetophenone yield, realizing reasonable cyclic utilization of side product, and reducing production cost, and is suitable for industrialized production.

Description

technical field [0001] The invention relates to the field of chemical synthesis, in particular to a synthesis method of p-hydroxyacetophenone. Background technique [0002] p-Hydroxyacetophenone, because its molecule contains hydroxyl and ketone groups on the benzene ring, is often used as an intermediate in organic synthesis to react with other compounds to synthesize many important substances. Generally used to synthesize pharmaceutical intermediates (α-bromo-p-hydroxyacetophenone, choleretic drugs, antipyretic and analgesic drugs, etc.), others (spices, feed, etc.; pesticides, dyes, liquid crystal materials, etc.). [0003] In the prior art, phenol is used as a raw material to synthesize p-hydroxyacetophenone, generally through esterification to prepare phenyl acetate, and then through Fries rearrangement reaction to prepare p-hydroxyacetophenone. There are two situations of one-step synthesis method and two-step synthesis method. One-step synthesis method such as DE3108...

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Problems solved by technology

There are two situations of one-step synthesis method and two-step synthesis method. One-step synthesis method such as DE3108076 discloses a synthesis method for preparing p-hydroxyacetophenone (name: Process for the preparation of o-and p-acyl phenols, publication date 1982.09. 16), using phenol as raw material, under the catalysis of aluminum trichloride, adding acetyl chloride to prepare 31.5% p-hydroxyacetophenone and 68.5% o-hydroxyacetophenone, the total yield is 89%, the method Mainly to prepare the ortho-position product, the yield of p-hydroxyacetophenone obtained by it is too low, which is not ideal; ), with phenol and acetic anhydride as raw materials, with the aluminum chloride of 3-4 mol ratio as catalyst one-step method to prepare o-hydroxyacetophenone and p-hydroxyacetophenone, the total yield is 90.2%, o-hydroxyl The proportion of acetophenone is 80.5%, which is also mainly for the preparation of o-hydroxyacetophenone

[0004] The two-step synthesis method, such as the Chinese patent "a preparation method of o-hydroxyacetophenone and p-hydroxyacetophenone" (publication number: CN102093189A, publication date 2015.04.22), is to react phenol and acetic anhydride to obtain phenol acetate, Then add phenyl acetate to Lewis acid, the product obtained is hydrolyzed with glacial hydrochloric acid, the organic layer is separated by standing method, after the organic layer is frozen and filtered, the obtained filter cake is recrystallized with water and decolorized with activated carbon to obtain p-hydroxyacetophenone (about 37%), the filtrate obtained after the organic layer is frozen and filtered is steam distilled, and o-hydroxyacetophenone (about 54%) is obtained through rectification under reduced pressure; the p-hydroxyacetophenone yield obtained by this method It is higher than the one-step synthesis method, but it is also dominated by the ortho-position, and the yield of the para-position product is not ideal enough, so it is not suitable for industrial production

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