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Method for preparing pyroxasulfone intermediate 5, 5-dimethyl-4, 5-dihydroisoxazole-3-thioformamidine hydrochloride

A technology of thioformamidine hydrochloride and dihydroisoxazole, which is applied in the field of pesticide herbicide synthesis, can solve the problems of cumbersome operation, harsh reaction conditions, and sudden cost rise, and achieve simple reaction operation, low raw material cost, The effect of less by-products

Active Publication Date: 2021-04-13
JIANGSU FLAG CHEM IND
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  • Abstract
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AI Technical Summary

Problems solved by technology

[0033] The above-mentioned reaction method seems to be simple, and the yield can be higher, but the reaction conditions are relatively harsh, the ratio of acetonitrile and water is strict, the recovery is difficult, and after the actual reaction temperature rises (greater than 20 ° C), often The phenomenon of reaction stagnation occurs, and it is easy to generate isomeric impurities. It is difficult to separate compound Ⅱ, and the yield will decrease more; if compound Ⅱ is not separated and fed continuously, the purity of the follow-up product compound Ⅰ is difficult to guarantee; the purification of compound Ⅰ is after many Sub-concentration and multiple solvent treatment to remove insolubles and wash impurities are extremely cumbersome; in addition, after continuous reaction of chlorination and salt formation, the solvent acetonitrile and water are recovered due to impurities such as sulfur, and the chlorination impurities will be significantly increased after applying mechanically. increase, it will also lead to stagnation in the late stage of the reaction, and the reaction is not complete; it is very unfavorable for industrial production, resulting in a sudden increase in costs
[0034] In view of this, the preparation methods of compound II and compound I reported in the above-mentioned relevant patents all have defects to a certain extent, such as unstable intermediates, serious pollution of three wastes, cumbersome operation, etc., which are not conducive to the needs of industrial production; therefore, there is an urgent need for a A stable intermediate, less pollution from three wastes, easier to operate, and suitable for industrial production of pyrazazole intermediate 5,5-dimethyl-4,5-dihydroisoxazole-3-thioformamidine salt Synthesis method of acid salt

Method used

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  • Method for preparing pyroxasulfone intermediate 5, 5-dimethyl-4, 5-dihydroisoxazole-3-thioformamidine hydrochloride
  • Method for preparing pyroxasulfone intermediate 5, 5-dimethyl-4, 5-dihydroisoxazole-3-thioformamidine hydrochloride
  • Method for preparing pyroxasulfone intermediate 5, 5-dimethyl-4, 5-dihydroisoxazole-3-thioformamidine hydrochloride

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0057] In a 1000ml dry four-neck flask, add 99.13g (1.0mol) of 5,5-dimethyl-4,5-dihydroisoxazole and 700g of dichloromethane, cool down to 0-5°C, stir and drop in 98% Concentrated sulfuric acid 50g (0.5mol), stirred rapidly for 30 minutes, a large amount of white solids precipitated, slowly cooled to 0-5°C, introduced 78g (1.1mol) of chlorine gas to react, GC monitored the disappearance of the raw material ring compound, stood still, and separated , the acid layer was extracted once with 100 g of dichloromethane, the acid layer was collected and used mechanically, the organic layer was combined, and the organic layer was washed once with 100 g of water to obtain a dichloromethane solution containing compound II. The purity is 99.8%, and the total yield of two steps of salt formation and chlorination: 98.9%.

[0058] Transfer about 925 g of the above dichloromethane solution containing 132.11 g of compound II to a 1000 ml four-neck flask, add 40 g (0.395 mol) of 36% concentrate...

Embodiment 2

[0064] The recovered acid layer in Example 1 was placed in a 250ml dry four-necked bottle, stirred and cooled to below 20°C, dripped in chlorosulfonic acid until no bubbles were precipitated, kept warm and stirred for 30 minutes, then passed nitrogen gas and raised the temperature to 40°C for 30 minutes to discharge hydrogen chloride Gas, cooled and sealed for later use.

[0065] In a 1000ml dry four-necked flask, add 5,5-dimethyl-4,5-dihydroisoxazole 99.13 (1.0mol), dichloromethane 600g, cool down to 0-5°C, stir and drop into the above-mentioned dry recovery Concentrated sulfuric acid 50g (0.5mol), stirred rapidly for 30 minutes, a large amount of white solids precipitated, slowly cooled to 0 ~ 5 ℃, passed through 85.08g (1.2mol) of chlorine gas to react, GC monitoring raw material ring compound disappeared, stand still, separate layer, the acid layer was extracted once with 100 g of dichloromethane, the acid layer was collected and used mechanically, the organic layer was co...

Embodiment 3

[0068] In a 1000ml dry four-neck flask, add 5,5-dimethyl-4,5-dihydroisoxazole 99.13 (1.0mol), dichloroethane 500g, cool down to 0-5°C, stir and drop in 98% Concentrated sulfuric acid 50g (0.5mol), stirred rapidly for 30 minutes, a large amount of white solids precipitated, slowly cooled to 0 ~ 5 ℃, passed through 85.08g (1.2mol) of chlorine gas to react, GC monitoring raw material ring compound disappeared, stand still, separate The acid layer was extracted once with 100 g of dichloroethane, the acid layer was collected and used mechanically, the organic layer was combined, and the organic layer was washed once with 100 g of water to obtain a dichloroethane solution containing 131.3 g of compound II, with a weight of about 930 g and a content of 99.5%. , two-step total yield of salt formation and chlorination: 98.3%.

[0069] About 930 g of the above-mentioned dichloroethane solution containing 131.3 g of compound II was transferred to a 1000 ml four-neck flask, 30 g (0.296 mo...

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Abstract

The invention relates to the field of pesticide herbicide synthesis, in particular to a method for preparing a sulfonylpyraflufen-ethyl intermediate 5, 5-dimethyl-4, 5-dihydroisoxazole-3-thioformamidine hydrochloride, which comprises the following steps: reacting a compound IV with strong acid to form salt to obtain a compound III; directly carrying out chlorination reaction on the compound III and chlorine without purification to obtain a chlorination product compound II; and reacting the compound II with thiourea in an organic solvent in the presence of inorganic acid to obtain a compound I. According to the method, the compound IV is used as a raw material, the raw material cost is low, salifying and chlorination are performed to obtain the product compound II, byproducts are few, reaction operation is easy and convenient, and pollution is small; AND finally, the compound I is prepared by directly reacting with thiourea in the presence of inorganic acid, the yield of a finished product is up to 90% or above, the purity can reach 99%, a used solvent can be completely recycled, and the method is very suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of synthesis of pesticide herbicides, and in particular relates to a method for preparing the intermediate 5,5-dimethyl-4,5-dihydroisoxazole-3-thioformamidine hydrochloride of pyrazafen. Background technique [0002] 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole II, 5,5-dimethyl-4,5-dihydroisoxazole-3-thioformamidine hydrochloride Ⅰ is a key intermediate for the synthesis of the herbicide pyroxasulfone, and pyroxasulfone (4-Pyroxasulfone) is produced by Kumiai Chemical Industry Co., Ltd. and Ihara Chemical Co., Ltd. Industry Co., Ltd.) developed a new pre-emergence herbicide that can effectively control grass and broad-leaved weeds in corn fields, soybean fields and wheat fields. [0003] [0004] Metrafenazole is a pre-emergence soil treatment herbicide, which can be safely used in corn, soybean, cotton, peanut, sunflower and potato. It is a broad-spectrum herbicide, which can effectively control annual grass weeds...

Claims

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Application Information

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IPC IPC(8): C07D261/04
CPCC07D261/04
Inventor 陈庆宏梅宇张璞
Owner JIANGSU FLAG CHEM IND
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