Method for synthesizing 2(3H)-benzofuranone by utilizing microwave

Abstract

The invention discloses a method for synthesizing 2(3H)-benzofuranone by utilizing microwave, which comprises the following steps: after making o-chloro or o-bromo, o-iodophenylacetic acid react at a high temperature or a high temperature and a high pressure, acidifying the material, extracting the raw material without any solvent, and then directly dehydrating the material under a negative pressure, directly transferring the material into a microwave reactor with a stirrer, setting power; after monitoring the reaction completely with HPLC (high-performance liquid chromatography), changing a dehydration device into an external negative-pressure microwave condensing device, setting distilling power, collecting fractions and cooling to obtain a light yellow crystalline solid that is 2(3H)-benzofuranone. The method provided by the invention is a process for synthesizing 2(3H)-benzofuranone, which has the advantages of simple operation, short production period, low energy consumption, no solvent and high yield, and being green and pollution-free.

Description

technical field [0001] This paper relates to the field of chemical synthesis, in particular to a method for synthesizing 2(3H)-benzofuranone by microwave. Background technique [0002] Azoxystrobin is a methoxyacrylic fungicide developed by Syngenta, and currently ranks first in sales of fungicides, and 2(3H)-benzofuranone is a key intermediate of the fungicide azoxystrobin. At present, the main synthetic methods at home and abroad use o-chlorophenylacetic acid or o-bromophenylacetic acid, or o-iodophenylacetic acid as starting materials, after high temperature and high pressure reaction, acidification, solvent extraction, and crystallization to obtain o-hydroxyphenylacetic acid. The rate is about 60%. Dissolve o-hydroxyphenylacetic acid with 3 to 4 times of toluene, then add sulfuric acid or p-toluenesulfonic acid as a dehydration catalyst, react at a high temperature of 110°C to 120°C for 8h to 12h, reflux and dehydrate, wash with water and remove toluene. Another solvent...

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Problems solved by technology

At present, the main synthetic methods at home and abroad use o-chlorophenylacetic acid or o-bromophenylacetic acid, or o-iodophenylacetic acid as starting materials, after high temperature and high pressure reaction, acidification, solvent extraction, and crystallization to obtain o-hydroxyphenylacetic acid. The rate is about 60%. Dissolve o-hydroxyphenylacetic acid with 3 to 4 times of toluene, then add sulfuric acid or p-toluenesulfonic acid as a dehydration catalyst, react at a high temperature of 110°C to 120°C for 8h to 12h, reflux and dehydrate, wash with water and remove toluene. Another solvent is recrystallized to obtain 2(3H)-benzofuranone, and the single-step yield is about 88%. The cycle of this method from o-chlorophenylacetic acid to o-hydroxyphenylacetic acid is about 40h, which is long and requires The extraction and recrystallization crystallization yields are low, mainly due to the relatively good solubility of o-hydroxyphenylacetic acid in acid water, which brings difficulty in extraction, resulting in the need for three kinds of solvents and a large amount of dehydration catalyst in the whole preparation process. Although some solvents can be recovered, However, the recovery cost is high, the environmental cost is increased, and the dehydration is carried out at high temperature for a long time, resulting in partial carbonization and polymerization of the product to produce tar, which makes the color of 2(3H)-benzofuranone yellow and the content is 97%. or so, the two-step total yield is only 52.8%