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Catalytic synthesis method of mefenpyr-diethyl

A technology of pyrazole and cyclization reaction, applied in the direction of organic chemistry and the like, can solve the problems of complex process and low yield, and achieve the effects of simple process, high product quality and high product yield

Inactive Publication Date: 2012-12-12
JIANGSU TIANRONG GROUP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The process is complicated and the yield is low

Method used

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  • Catalytic synthesis method of mefenpyr-diethyl

Examples

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Embodiment 1

[0024] Embodiment 1, the synthesis of ethyl chloroacetoacetate

[0025] Add 1 mol of ethyl acetoacetate into the reaction flask, start stirring, and lower the temperature. When the temperature of the material drops to 0°C, start to add 1.05 mol of sulfuryl chloride dropwise. During the dropping process, keep the temperature at 0-5°C. After the addition is complete, keep warm for 0.5 hours, take a sample and control it, and the reaction is completed if the residual triethyl ester is ≤0.2%. Raise the temperature to 80°C and keep it warm for 1 hour. After the heat preservation was completed, cool to 50°C, add 100ml of water, stir for half an hour, statically separate the layers, wash the organic layer with water until neutral, and obtain ethyl chloroacetoacetate with a content of 98% and a yield of 97%.

Embodiment 2

[0026] Example 2, the synthesis of 2-chloro-2-(2,4-dichlorophenylhydrazone)-ethyl glyoxylate

[0027] Put 350ml of hydrochloric acid and 400ml of water into the reaction bottle, start stirring, then put in 100g of 2,4-dichloroaniline, cool to below 0°C (above -10°C), start to add dropwise sodium nitrite aqueous solution (44g of sodium nitrite, 100ml water), dropwise adding time 2-2.5 hours. During the whole dropping process, the temperature of the material should be kept between -5 and 0°C. The generated diazonium salt is used for later use.

[0028] Put 600ml of methanol and 200ml of water into another reaction bottle, put 400g of sodium acetate under stirring, and then add 110g of chlorotriethyl ester (ie ethyl chloroacetoacetate). The temperature was lowered to 15°C, and the diazo liquid was added dropwise, and the whole dropping time was about 1 hour. After the dropwise addition, keep the temperature for 3 hours. After the heat preservation is over, discharge the materi...

Embodiment 3

[0029] Embodiment 3, cyclization

[0030] Put 500g of ethyl methacrylate and 450g (95%) 2-chloro-2-(2,4-dichlorophenylhydrazone)-ethyl glyoxylate into the reaction bottle, then add 10g of triethylamine and 2, 2g of 5-di-tert-butylhydroquinone, raise the temperature to 60°C and start to add potassium bicarbonate solution (150g of potassium bicarbonate dissolved in 550mL of water) dropwise, and drop it in about 3 hours. After the dropwise addition, keep warm for 2.5 hours, stand still for 30 minutes, and separate the lower layer of waste water. Start to heat up, high-vacuum precipitation, the precipitation is completed, add 350mL of methanol, cool down, wait until the temperature reaches -5 ° C, centrifuge to obtain 505g of product, the content is 95.2%, and the yield is 88%. Melting point: 50∽52°C. Embodiment 4, the synthesis of ethyl chloroacetoacetate

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Abstract

The invention discloses a catalytic synthesis method of (RS)-1-(2,4-dichlorophenyl)-5-methyl-2-pyrazol-3,5-dicarboxylate, comprising the following steps of: A, diazotization: a diazo reaction is carried out by the use of 2,4-dichloroaniline, hydrochloric acid and sodium nitrite so as to obtain aniline diazo salt; B, synthesis of chloro-ethyl acetoacetate: chlorination is carried out by the use of ethyl acetoacetate and sulfuric chloride to obtain chloro-ethyl acetoacetate; C, synthesis of 2-chlorine-2-(2,4-dichlorophenylhydrazone)-ethyl glyoxalate: diazo salt obtained from the step A reacts with chloro-ethyl acetoacetate obtained from the step B under the action of a catalyst to obtain 2-chlorine-2-(2,4-dichlorophenylhydrazone)-ethyl glyoxalate; and D, cyclization: a cyclization reaction between 2-chlorine-2-(2,4-dichlorophenylhydrazone)-ethyl glyoxalate obtained from the step C and methyl methacrylate is carried out so as to obtain (RS)-1-(2,4-dichlorophenyl)-5-methyl-2-pyrazol-3,5-dicarboxylate. The method provided by the invention has advantages of simple technology, easily-obtained raw materials and high yield of the product.

Description

technical field [0001] The invention belongs to the field of pharmaceutical compounds, in particular to a (RS)-1-(2,4-dichlorophenyl)-5-methyl-2-pyrazoline-3,5-dicarboxylic acid diethyl ester Catalytic synthesis method. Background technique [0002] (RS)-1-(2,4-dichlorophenyl)-5-methyl-2-pyrazoline-3,5-dicarboxylic acid diethyl ester, its structural formula is [0003] [0004] According to EP0635996, using 2,4-dichloroaniline as a raw material, the intermediate 2,4-dichlorophenylhydrazine was first prepared, and then azo was generated with monoethyl oxalyl chloride, and then chlorinated with phosphorus pentachloride to obtain 2 -Chloro-2-(2,4-dichlorophenylhydrazone)-ethyl glyoxylate, then perform Michael addition reaction with ethyl methacrylate, and then cyclize with base to obtain the target compound. [0005] [0006] [0007] The process is complicated and the yield is low. Contents of the invention [0008] The purpose of the present invention is to solv...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D231/06
Inventor 许网保魏明阳臧伟新虞国新
Owner JIANGSU TIANRONG GROUP
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