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Method for preparing imazethapyr

A technology of imazethapyr and ethyl nicotinic acid, which is applied in the direction of organic chemistry, can solve the problems of uncertain product crystal form and large amount of waste water, and achieve the effects of reducing raw material costs, improving quality, and increasing reaction speed

Active Publication Date: 2012-05-16
SHENYANG SINOCHEM AGROCHEMICALS R&D CO LTD +1
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

[0005] In order to solve the problems of large amount of waste water and uncertain crystal form of products existing in the prior art, the present invention proposes a new preparation method of imazethapyr

Method used

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  • Method for preparing imazethapyr

Examples

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example 1

[0026] Example 1 Synthesis of 2-[(1-cyano-1,2-dimethylpropyl)-formamido]-5-ethyl nicotinic acid

[0027]

[0028] Add 40.2g (0.2mol, 97%) of 5-ethylpyridinedicarboxylic acid, 23g (0.22mol, 97.6%) of acetic anhydride and 160g of xylene into a 500ml reaction flask, heat up and reflux for 0.5h, then cool down to 25-30°C , dropwise added 26g (0.22mmol, 95%) 2-amino-2,3-dimethylbutyronitrile, after the dropwise addition was completed, it was incubated at 8-12°C for 1h, and the HPLC tracking reaction was complete. After toluene, the temperature was lowered to precipitate a solid, which was filtered and dried to obtain 50.2 g of 2-[(1-cyano-1,2-dimethylpropyl)-carboxamido]-5-ethylnicotinic acid with a content of 97%. The rate is 87.3%.

example 2II

[0029] Example 2 II crystal form imazethapyr

[0030]

[0031]In a 500ml reaction flask, the 50.2g product (content 97%) obtained in Example 1 was dissolved in 106.7g (0.8mol, 30%) of NaOH aqueous solution, stirred for 10min, and 40.8g was added dropwise at room temperature 20-25°C (0.3mol, 25%) hydrogen peroxide, after the dropwise addition, keep warm at 20-25°C for 2h, then raise the temperature to 70°C for 2h, then raise the temperature to 90°C for 20min. Afterwards, cool down to 30°C-40°C, add hydrochloric acid dropwise to pH = 3-4, and keep for 20 minutes; then cool the material to 10°C, keep it warm for 30 minutes, and filter. The filter cake was washed three times with 50 g of water, and dried to obtain 56.2 g of product with a content of 98.7%, a yield of 96%, and a turbidity of 75 NTU.

[0032] MP: 171.4-173.9°C.

[0033] IR (cm -1 ) v: 3240, 2980, 1740, 1690-1680, 1640, 1460-1455, 1390, 1050, 685, 670, 610.

[0034] 1 HNMR (300Hz, CDCl 3 )δ: 8.825(s, 1H), 8....

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Abstract

The invention discloses a novel method for preparing imazethapyr. The novel method comprises the following steps of: preparing 5-ethyl-2,3-pyridinedicarboxylic anhydride from 5-ethyl pyridinedicarboxylic acid; reacting the 5-ethyl-2,3-pyridinedicarboxylic anhydride with 2-amino-2,3-dimethylbutyronitrile to prepare 2-[(1-nitrile-1,2-dimethylpropyl)-formylamino]-5-ethylnicotinic acid; and hydrolyzing cyan in sodium hydroxide or hydrogen peroxide to form amide, performing loop closing, and acidifying to prepare the imazethapyr. Meanwhile, the invention provides a novel aftertreatment method. By the preparation method, satisfactory yield can be achieved, raw material cost is reduced, and an II crystal form imazethapyr product with a stable crystal form and low turbidity can be obtained. Therefore, the method is suitable for large-scale industrial production.

Description

technical field [0001] The invention belongs to the field of organic synthesis, and relates to a preparation process optimization technology of the herbicide imazethapyr, in particular to a preparation method of imazethapyr. Background technique [0002] Imazethapyr, also known as imazethapyr, belongs to the class of imidazolinone herbicides and is a high-efficiency, low-toxicity, broad-spectrum soybean herbicide developed by the American cyanamide company in the 1980s. The chemical name of imazethapyr is (RS)-5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl) nicotinic acid, and its structural formula is as follows: [0003] [0004] There have been many reports on the preparation method of imazethapyr, such as US4861887, US4925944 and "Pesticide" 2001, 40(9): 9-12. The current production process basically adopts the hydrolysis of 2-amino-2,3-dimethylbutyronitrile under sulfuric acid, and the intermediate 2-amino-2,3-dimethylbutanamide and 5-ethyl-2,3- Reaction o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D401/04
Inventor 程春生任忠宝于萍明旭李鹏
Owner SHENYANG SINOCHEM AGROCHEMICALS R&D CO LTD
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