Method for preparing 2,5-dimethyl phenylacetic acid

A technology of dimethylphenylacetic acid and p-xylene, which is applied in the direction of carbon monoxide reaction to prepare carboxylic acid, preparation of halogenated hydrocarbons, chemical instruments and methods, etc., can solve the problems of high raw material prices, many synthesis steps, complex reaction types, etc. Achieve the effects of low production cost, high reaction yield and reasonable process conditions

Active Publication Date: 2012-11-14
LIANHE CHEM TECH +1
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  • Abstract
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Problems solved by technology

[0011] In view of this, in order to solve the problems of high raw material price, many synthesis steps and complicated reaction types in the above-mentioned existing preparation method of 2,5-dimethylphenylacetic acid, the invention provides a kind of raw material which is cheap and easy to obtain, The process is simple, the yield is high and the environment is friendly, and it is a new preparation method suitable for industrial production

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  • Method for preparing 2,5-dimethyl phenylacetic acid
  • Method for preparing 2,5-dimethyl phenylacetic acid
  • Method for preparing 2,5-dimethyl phenylacetic acid

Examples

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Embodiment 1

[0028] (1) Chloromethylation reaction

[0029] In a 500ml four-necked flask, add 48g of paraformaldehyde, 106g of p-xylene, 10g of 1-butyl-3-methylimidazole bromide, and 3.2g of concentrated hydrochloric acid with a concentration of 36%. After stirring evenly, the temperature rises to Charge hydrogen chloride gas at 80-85°C, keep warm for 0.5 hours after the hydrogen chloride gas has been flushed, and then let it stand for stratification after cooling down to room temperature, the upper layer is the organic layer, and the lower layer is the water layer. The water layer is dehydrated under reduced pressure, and the dehydrated ionic liquid can be recycled. The organic layer was transferred to a 500ml four-neck flask for rectification under reduced pressure, and 139.3g of 2,5-dimethylbenzyl chloride was finally obtained after precipitation, with a yield of 90.1%.

[0030] (2) Carbonylation and hydrolysis reactions

[0031] In a 1000ml autoclave, add 70.0g of the above-mentioned...

Embodiment 2

[0033] (1) Chloromethylation reaction

[0034] In a 500ml four-neck flask, add 24g of paraformaldehyde, 53g of p-xylene, 4.9g of 1-ethyl-3-methylimidazolium tetrafluoroborate, and 1.6g of concentrated hydrochloric acid with a concentration of 36%, and heat up after stirring When the temperature rises to 80-85°C, hydrogen chloride gas is filled. After the hydrogen chloride gas is filled, it is kept for 0.5 hours. After cooling down to room temperature, it is allowed to stand for stratification. The upper layer is the organic layer, and the lower layer is the water layer. The water layer is dehydrated under reduced pressure, and the dehydrated ionic liquid can be recycled. The organic layer was transferred to a 500ml four-neck flask for rectification under reduced pressure, and 70.6g of 2,5-dimethylbenzyl chloride was finally obtained after precipitation, with a yield of 91.3%.

[0035] (2) Carbonylation and hydrolysis reactions

[0036] In a 1000ml autoclave, add the above-me...

Embodiment 3

[0038] (1) Chloromethylation reaction

[0039] In a 250ml four-necked flask, add 36.0g of paraformaldehyde, 84.8g of p-xylene, 14.0g of 1-butyl-3-methylimidazole chloride, 2.4g of concentrated hydrochloric acid with a concentration of 36%, and heat up after stirring evenly. Fill in hydrogen chloride gas when the temperature rises to 80-85°C, keep the temperature for 0.5 hours after the hydrogen chloride gas is filled, let it stand and separate after cooling down to room temperature, the upper layer is the organic layer, and the lower layer is the water layer. The water layer is dehydrated under reduced pressure, and the dehydrated ionic liquid can be recycled. The organic layer was transferred to a 250ml four-neck flask for rectification under reduced pressure, and 113.4g of 2,5-dimethylbenzyl chloride was finally obtained after precipitation, with a yield of 91.7%.

[0040] (2) Carbonylation and hydrolysis reactions

[0041] In a 1000ml autoclave, add the above-mentioned re...

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Abstract

The invention discloses a method for preparing 2,5-dimethyl phenylacetic acid. The 2,5-dimethyl phenylacetic acid is a fine chemical engineering intermediate which is widely applied in fields of medicines and pesticides, and particularly is a key intermediate of spirotetramat serving as a novel insecticide. The method comprises the following steps of: mixing paraxylene serving as a raw material and ionic liquid serving as solvent with paraformaldehyde and concentrated hydrochloric acid, and performing a chloromethylation reaction to obtain 2, 5-dimethyl benzyl chloride; and performing a carbonylation reaction and a hydrolysis reaction of the 2, 5-dimethyl benzyl chloride and an acid-binding agent and the solvent in a reactor under the action of a catalyst to obtain the 2,5-dimethyl phenylacetic acid. The method has a novel process, short synthetic reaction steps, simplicity of operation, low production cost, high reaction yield, and environmental friendliness, and is suitable for industrial production.

Description

technical field [0001] The invention relates to a chemical synthesis method, in particular to a preparation method of a fine chemical intermediate 2,5-dimethylphenylacetic acid. Background technique [0002] 2,5-Dimethylphenylacetic acid is an important fine chemical intermediate, which is widely used in the fields of medicine and pesticides, especially, it is the key intermediate of the new insecticide spirotetramat, which It is the only insecticide with two-way systemic conduction so far. [0003] About the synthetic technology of 2,5-dimethylphenylacetic acid, mainly contain following several methods with reference to domestic and foreign literature: [0004] 1. Kazuhiko et al. used 2,5-dimethylbenzyl chloride as the initial raw material in Bulletin of the Chemical Society of Japan 1975, 48(2), 497-504, and synthesized 2,5 through two steps of cyanidation and hydrolysis. -Dimethylphenylacetic acid. The reaction process is as follows: [0005] [0006] 2. The synthe...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C57/30C07C51/10
CPCC07C17/32C07C51/10Y02P20/54C07C57/30C07C22/04
Inventor 王萍樊小彬林行军何朝晖
Owner LIANHE CHEM TECH
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