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Prepn of dibromochrysanthemic acid

A technology of dibromochrysanic acid and permethrin, which is applied in the preparation of carboxylate/lactone, organic chemistry, etc., can solve the problems of reduced reaction yield, many reaction by-products, excessive HBr, etc., to reduce pollution and Effects of waste water, improvement of purity and yield, and simplification of reaction conditions

Inactive Publication Date: 2003-05-14
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The shortcoming of its synthetic dibromochrysanthemic acid method is:
[0005] 1. The method of continuously feeding HBr in the reaction is adopted, and the HBr is greatly excessive, causing pollution and waste, and the requirements for equipment pipelines are also high;
[0006] 2. When permethrin is reacted with bromine salt, argon gas must be fed continuously under a certain degree of vacuum (20mmHg), a large amount of argon gas and solvent will be lost, and the process is complicated, resulting in unstable product quality;
[0007] 3. There are many by-products in the reaction. The dibromochrysanthemic acid obtained after the reaction is brown. It must go through the purification process of recrystallization and sublimation, which reduces the reaction yield and the operation process is cumbersome.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Example 1: 160ml of dibromoethane and a small amount of aluminum powder were added to a 500ml three-necked reaction flask, and 20ml of dry bromine (62g, 0.388mol) was poured into the reaction flask at 20°C. After 15 minutes, the reaction started, and the temperature was kept at 30-50° C., and aluminum powder (9.3 g, 0.345 mol) was gradually added until all the aluminum powder reacted to form a brown substance. Then the temperature of the system was lowered to 5° C., and nitrogen gas was blown into the system for 5 minutes to seal the system. 97% cis-permethrin (26.6 g, 0.127 mol) dissolved in 70 ml of dibromoethane was added dropwise to the aluminum tribromide solution, and the temperature was controlled between -5 and 5°C. The dropwise addition was controlled to be completed in half an hour, and the temperature was kept to continue the reaction for 1 hour. Pour the solution into a mixture of 200ml of dilute hydrochloric acid and ice cubes and stir vigorously, let the ...

Embodiment 2

[0025] Example 2: Add 60ml of methylene bromide and aluminum powder (10.3g, 0.381mol) in a 500ml three-necked reaction flask, heat the suspension to 45°C, and dissolve 20ml of dried bromine (62g, 0.388mol) in 100ml of methylene bromide In, slowly drop into the aluminum powder. The temperature is maintained at 30-50°C until all the aluminum powder reacts to form a brown product. Then the temperature of the system was lowered to 0° C., and nitrogen gas was blown into the system for 5 minutes to seal the system. Permethrin (cis / trans=45 / 55, 26.6 g, 0.127 mol) dissolved in 70 ml of dibromomethane was added dropwise to the aluminum tribromide solution, and the temperature was controlled between -5 and 5°C. The dropwise addition was controlled to be completed in half an hour, and the temperature was kept to continue the reaction for 2 hours. Pour the solution into a mixture of 200ml of dilute hydrochloric acid and ice cubes and stir vigorously, statically separate the layers, extr...

Embodiment 3

[0026] Example 3: 160ml of carbon disulfide and a small amount of aluminum powder were added to a 500ml three-necked reaction flask, and 20ml of dry bromine (62g, 0.388mol) was poured into the reaction flask at 20°C. After 15 minutes, the reaction was started, and the temperature was kept at 30-40° C., and aluminum powder (9.3 g, 0.345 mol) was gradually added until all the aluminum powder reacted to form a black substance. Then the temperature of the system was lowered to -30° C., and nitrogen gas was blown into the system for 5 minutes to seal the system. 97% cis-permethric acid (26.6 g, 0.127 mol) dissolved in 70 ml of carbon disulfide was added dropwise to the aluminum tribromide solution, and the temperature was controlled between -35 and -25°C. The dropwise addition was controlled to be completed in half an hour, and the temperature was kept to continue the reaction for 24 hours. The solution was poured into a mixture of 200 ml of dilute hydrochloric acid and ice cubes ...

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PUM

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Abstract

Using dichlorochrysanthemic acid as raw material, dibromochrysanthemic acid is prepared through the direct halogen exchange reaction of AlBr3 with dichlorochrysanthemic acid, with obtaining tribromochrysanthemic acid as side product. Through an added HBr eliminating reaction, the tribromochrysanthemic acid as side product is converted into dibromochrysanthemic acid. The dibromochrysanthemic acid product with purity of 97% is obtained in the total yield of 91%. During the reaction, the product and the raw material have their configuration maintained.

Description

technical field [0001] The invention relates to a method for synthesizing permethrin from permethrin. Background technique [0002] Dibromothrin is an intermediate compound in the synthesis of the high-efficiency insecticide-deltamethrin. Dibromochrysanthemic acid, namely 2,2-dimethyl-3-(2,2-dibromovinyl)cyclopropaneic acid, as shown in (I) In deltamethrin, the desired configuration of the didelmethrin moiety is cis-dextral. [0003] At present, there are many methods for synthesizing dibromochrysanthemic acid, but the raw materials are often difficult to obtain in China, or the equipment requirements are relatively high, and a high-power ozone generator is needed, so the large-scale production of dibromochrysanthemic acid has not yet been realized in China. [0004] In literature (1) converting permethrin and esters into dibromo analogs (Kiyoshi Kondo et al.US.4,188,492), (2) a method of converting ethyl permethrin into ethyl dibromothrin Synthetic method (Kiyohide Mats...

Claims

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Application Information

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IPC IPC(8): C07C51/09C07C61/40
Inventor 黄为韩梅白长敏陈惠麟于万滢郑卓
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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