Preparation method of 3-(alpha- methoxyl) methylene benzofuran-2(3H)-ketone

Abstract

The invention discloses a preparation method of 3-(alpha- methoxyl) methylene benzofuran-2(3H)-ketone. The method comprises the following steps of mixing benzofuran-2(3H)-ketone, trimethyl orthoformate and lewis acid, heating the mixture, adding recrystallization solvent after the reaction is ended, and cooling, crystallizing, filtering and drying the product to obtain the 3-(alpha- methoxyl) methylene benzofuran-2(3H)-ketone. The preparation method of the 3-(alpha- methoxyl) methylene benzofuran-2(3H)-ketone adopts the lewis acid catalysis. Compared with the prior art, no anhydride is added in the reaction, the high vacuumness and high temperature are not needed to recycle the excessive anhydride and byproducts produced by the anhydride after the reaction, so that the coking and sublimation phenomenon of the product can be avoided, and the recycling process is simple and convenient; and meanwhile, compared with preparation method adopting acetic acid as the catalyst, the consumption of the lewis acid is less, the consumption of raw materials can be greatly reduced, and the atom economy is good.

Description

technical field [0001] The invention relates to a preparation method of 3-(α-methoxy)methenylbenzofuran-2(3H)-one. Background technique [0002] 3-(α-methoxy)methenylbenzofuran-2(3H)-one is an important intermediate in the synthesis of the fungicide azoxystrobin, and the literature reports the production of 3-(α-methoxy)methenylbenzene There are three methods for furan-2(3H)-one: [0003] 1. O-hydroxyphenylacetic acid is dehydrated under the catalysis of acid to generate benzofuran-2(3H)-one, which is separated and purified or reacted with acetic anhydride and trimethyl orthoformate in one pot to obtain the target product, while by-products acetic acid and Methyl acetate, the reaction can use solvents such as toluene or without any solvent, and the reaction formula is as follows: [0004] [0005] For detailed preparation methods, see patent publication No. US5760250 and patent publication No. CN1219537A, Pesticides, 2004, 43(9), 414-416. [0006] 2. o-Hydroxyphenylace...

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Problems solved by technology

[0010] 1) Excessive acetic anhydride, the mixture of acetic acid and acetic anhydride needs to be recovered after the reaction, and the acetic acid and acetic anhydride need to be separated by rectification and purification, the process is complicated and the energy consumption is high;

[0011] 2) Due to the high boiling point of acetic anhydride, high temperature and high vacuum are required to recover excess acetic anhydride, and the product is prone to sublimation and carbonization;

[0012] 3) Excessive trimethyl orthoformate, not only high production cost, but also easy to decompose into methyl formate during the reaction process, and distill the reaction system together with the by-product methyl acetate, which needs to be discarded directly or separated by rectification to obtain methyl acetate and Methyl formate, complex process, increased energy consumption, high consumption of raw materials

The use of acetic acid is too large, still uneconomical

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