Synthetic method of benzofuran-2(3H)-one

Abstract

The invention discloses a synthetic method of benzofuran-2(3H)-one. The method comprises the following steps: hydrolyzing o-clorophenylacetic acid by using a sodium hydroxide solution under the catalysis of a catalyst to generate sodium 2-hydroxyphenylacetate, adding hydrochloric acid to acidify the above obtained reaction solution, cooling for crystallizing the above obtained acidification product, filtering obtained crystals to obtain sodium chloride-containing 2-hydroxyphenylacetic acid, and carrying out a lactonization reaction in a water carrying agent under the catalysis of iron sulfate to generate benzofuran-2(3H)-one. The method has the advantages of simplicity, easiness in implementation, good economic property, high yield, realization of operation simplification, 2-hydroxyphenylacetic acid loss avoiding and yield increase due to omission of the 2-hydroxyphenylacetic acid purifying process by carrying out the lactonization reaction on sodium chloride-containing crude 2-hydroxyphenylacetic acid directly used as a raw material, and realization of small corrosion to a reaction device, difficult in product carbonization, small catalysis use amount, no complex post-treatment, production cost saving and reduction of generation of three wastes due to iron sulfate being a neutral substance.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis and relates to a method for synthesizing organic compounds. Background technique [0002] Benzofuran-2-(3H)-one is an important organic synthesis intermediate, which can be used in the synthesis of medicine, pesticide azoxystrobin and new antioxidants. One of its main synthesis methods is to hydrolyze o-chlorophenylacetic acid with sodium hydroxide solution under the catalysis of a catalyst (copper powder or copper salt) to generate o-hydroxyphenylacetic acid sodium salt, neutralize the reaction solution with hydrochloric acid to neutrality, filter, filter The cake (sodium chloride and catalyst) is dried and recovered, the filtrate is concentrated, and excess hydrochloric acid is added, filtered, washed with water, and dried to obtain o-hydroxyphenylacetic acid; ) under the catalysis of lactonization reaction, the water generated by the reaction is removed by azeotropic distillation, th...

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Problems solved by technology

[0004] The shortcoming of this method is: 1, in the hydrolytic acidification reaction step, because part of sodium chloride is very easy to separate out with o-hydroxyphenylacetic acid, thereby need to wash with water or recrystallize, lose part o-hydroxyphenylacetic acid product, reduce yield rate, increasing the amount of wastewater produced

2. In the lactonization reaction step, strong acid concentrated sulfuric acid or p-toluenesulfonic acid is used as a catalyst, which not only corrodes the equipment greatly, but also easily carbonizes the product. After the reaction, it must be removed by alkali washing and water washing. A large amount of waste water is produced while lye is consumed, and the organic phase after washing needs to be dried, not only the product is lost, but also the waste desiccant needs to be treated separately

But this method also has the following disadvantages: 1, the catalyst concentrated sulfuric acid can react with by-product sodium chloride to generate hydrogen chloride and sodium sulfate, which not only consumes a large amount of concentrated sulfuric acid, but also produces a large amount of acid gas, waste residue and waste water

2. The reaction solution contains a large amount of inorganic salts, which makes stirring difficult, separation difficult, and high cost

3. After the reaction is finished, excess sulfuric acid and by-product sodium sulfate must be removed by alkali washing and water washing. A large amount of waste water will be generated while lye is consumed, and the organic phase after water washing needs to be dried. Need to be dealt with separately

The method uses acetic acid to catalyze the synthesis of lactone, which does not react with sodium chloride, and can be removed by vacuum distillation after the reaction, without washing and drying processes, and no saline waste water is produced, but its disadvantages are: 1, acetic acid and toluene It is easy to form an azeotrope with water and be taken out of the reaction system. In order to completely react o-hydroxyphenylacetic acid, a large amount of acetic acid must be used, and the acetic acid entering the water increases the difficulty of wastewater treatment and increases the production cost of the product

2. Since the system contains a large amount of sodium chloride, the stirring requirements for the reaction equipment are high

[0007] As can be seen from this, there are various deficiencies in the prior art, which limits the production of benzofuran-2-(3H)-ketone

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