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Preparation method of 3,4-dichloro-5-cyan-isothiazole

A technology of isothiazole and cyano group, applied in 3 fields, can solve the problems of polluting the environment, difficult to sell, low product purity, etc.

Active Publication Date: 2012-09-05
HUBEI CHENGYU PHARMA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Such a large amount of waste water containing organic matter such as dimethylformamide and by-products in the reaction will seriously pollute the environment
German patent DE 102005031348A1 uses chlorine gas to distill off dimethylformamide, dissolves it with alcohol, and heat filters it to obtain 3,4-dichloro-5-cyano-isothiazolol solution containing impurities, which avoids the generation of waste water, but After concentration, the product contains a large number of impurities that are difficult to remove, and the product is of low purity, making it difficult to sell as a commodity

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0008] Add 500 ml of dimethylformamide to a 1-liter four-neck flask, add 49 grams (1 mole) of sodium cyanide under stirring, cool with a water bath, and lower the temperature of the reaction solution to 20°C, and start to drop 79.8 grams of about 1.05 moles of carbon disulfide, and the rate of addition is controlled to keep the temperature of the reaction solution between 20-30°C. After dropping, continue stirring at room temperature for 1 hour, heat to 60°C, and keep stirring at 60°C for 3 hours. A large amount of solid precipitated out after standing for more than 12 hours. Stir to allow the solid to disperse in the reaction solution, cool with icy brine, and introduce 35 grams of chlorine gas. During the introduction of chlorine gas, the color of the reaction solution changes from dark brown to red, then dark brown, then red, orange, Then it turns brown, dark brown, light brown. Heating to 50°C with a heating mantle, insulated and stirred for 1 hour, and continued to intr...

Embodiment 2

[0012] Add 500 milliliters of dimethylformamide to a 1-liter four-neck flask, add 49 grams (1 mole) of sodium cyanide under stirring, cool with a water bath, and lower the temperature of the reaction solution to 20° C., and begin to dropwise add 79.8 grams ( 1.05 mol) of carbon disulfide, the rate of addition is controlled, and the temperature of the reaction solution is maintained between 20-30°C. After dropping, continue stirring at room temperature for 1 hour, heat to 60°C, and keep stirring at 60°C for 3 hours. Leave to separate out a large amount of solids more than 12 hours; Stir, allow solids to disperse in the reaction solution, cool with icy brine, introduce 31 grams of chlorine, during the introduction of chlorine, the color of the reaction solution changes the same as example 1. Heating to 50°C with a heating mantle, insulated and stirred for 1 hour, and continued to introduce 50 g of chlorine gas under stirring. The temperature was raised to 60° C., and the temper...

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Abstract

The invention provides a preparation method of 3,4-dichloro-5-cyan-isothiazole. The 3,4-dichloro-5-cyan-isothiazole is an important midbody of a series of isothiazole pesticides and medicines. The invention also discloses a green preparation method, comprising the following steps of: suspending sodium cyanide in dimethylformamide, dropping carbon disulfide at 20-30 DEG C, reacting for 3h at 60 DEG C, introducing chlorine in a reaction mixture, reacting for 3h at 60 DEG C, decompressing and recycling dimethylformamide, adding ethyl acetate in residue for backflow and dissolution, cooling and then filtering to remove undissolved substances, recycling ethyl acetate, cooling, crystallizing, filtering to obtain a first product, adding water to the mother liquor and distilling to obtain a second product, wherein the water for filtering the product can be circularly used. The invention avoids waste water emission in the whole production process. The yield ranges from 50-60%, the melting point ranges from 80 to 84 DEG C and the purity is 98% above.

Description

[0001] The present invention relates to a preparation method of 3,4-dichloro-5-cyano-isothiazole. 3,4-Dichloro-5-cyano-isothiazole is an important intermediate of a series of isothiazole pesticides and medicines, with a molecular formula of C4C12N2S and a molecular weight of 179.03. Background technique [0002] There are few domestic and foreign reports on the preparation method of 3,4-dichloro-5-cyano-isothiazole. German patents DE2231097 and DE2231098 are prepared by reacting trichloroacetonitrile or 2,3-dichloromaleonitrile with excess sulfur in a sealed tube at 200 to 300°C. This requires autoclave equipment, which is cumbersome to operate. US 3341547 and US 5240951 use sodium cyanide suspended in dimethylformamide to react with carbon disulfide, and then react with chlorine to prepare 3,4-dichloro-5-cyano-isothiazole. After the reaction of these two patents, the reaction solution was added into a large amount of water to precipitate the crude product, which was further...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D275/03
Inventor 温素姐洪蕾彭金平谢贤俊
Owner HUBEI CHENGYU PHARMA
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