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New preparation process of 6-chloro-2-hydroxyquinoxaline

A hydroxyquinoxaline, a new process technology, applied in the field of pesticides, can solve the problems of high reaction temperature, long reaction time, complicated dropping device, etc.

Inactive Publication Date: 2011-09-14
ANHUI FENGLE AGROCHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

U.S. Patent (US4620003) adopts Raney nickel as a catalyst, and hydrazine hydrate as a reducing agent, and 6-chloro-2-hydroxyquinoxaline-4-oxide is selectively reduced in aqueous sodium hydroxide solution to obtain 6-chloro-2 -Hydroxyquinoxaline, in this method, the catalyst and reducing agent are dropped into the reaction solution at 40-50°C, and then start to react at 40-70°C for 5 hours, so this method requires two dropping devices, And because the catalyst is a slurry, the dropping device used is relatively complicated, and the reaction temperature is relatively high and the reaction time is long

Method used

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  • New preparation process of 6-chloro-2-hydroxyquinoxaline

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Embodiment 1

[0006] Embodiment one: a kind of new preparation technology of 6-chloro-2-hydroxyquinoxaline, this technique uses Raney nickel as catalyst, hydrazine hydrate prepares 6-chloro-2-hydroxyquinoxaline as reducing agent, reaction formula is as follows :

[0007]

[0008] In a 500 ml four-necked flask equipped with a thermometer, a stirrer and a condenser tube, add 0.1 mol of p-chloro-o-nitroacetoacetanilide, add 200 ml of 10% sodium hydroxide solution, stir evenly and heat up to 65°C, keep warm After stirring for 1 hour, about 50 ml of ethanol was added, and the temperature of the reaction mixture solution was cooled to 30° C., 0.5 g of catalyst Raney nickel and 5 g of 80% hydrazine hydrate were added, and the mixture was kept stirring for 2 hours. After the reaction is over, filter (the filtered catalyst is used directly next time), distill ethanol from the filtrate under reduced pressure (the evaporated solvent is used directly next time), add an appropriate amount of acid to ...

Embodiment 2

[0009] Embodiment two: in the 500 milliliter four-neck flask that thermometer, stirrer and condenser tube are housed, add the p-chloro-o-nitroacetoacetanilide of 0.1mol, add 200 milliliters of 10% sodium hydroxide solution, stir and heat up to 65 DEG C, after insulated and stirred for 1 hour, add about 50 milliliters of ethanol (recovery in embodiment one), the reaction mixture solution is cooled to 30 DEG C, add catalyst Raney nickel (recovery in embodiment one) 0.5 grams and 5 grams of 80% hydrazine hydrate, Keep warm and stir for 2 hours. After the reaction is over, filter (the filtered catalyst is used directly next time), distill ethanol from the filtrate under reduced pressure (the evaporated solvent is used directly next time), add an appropriate amount of acid to acidify to neutrality, filter, and filter cake Washed with water and dried to obtain 15.0 g of the product, the yield was 83.3% based on p-chloro-o-nitroacetoacetanilide.

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Abstract

The invention provides a new preparation process of 6-chloro-2-hydroxyquinoxaline. In the process, in a mixed solvent with a catalyst Raney nickel, hydrazine hydrate is utilized to reduce closed-ring substances, which are formed by chloro-o-nitro-acetoacetanilide in an alkali solution, to generate the 6-chloro-2-hydroxyquinoxaline. The invention is characterized in that a one-pot method is adopted, and the adopted mixed solvent is ethanol plus water. The process reduces the consumptions of acid and alkali, simplifies the reactor, lowers the reaction temperature and shortens the reaction time, and the total yield of the product is up to higher than 83%.

Description

technical field [0001] The invention belongs to the technical field of pesticides, and in particular relates to a new preparation process of 6-chloro-2-hydroxyquinoxaline. Background technique [0002] 6-Chloro-2-hydroxyquinoxaline is a key intermediate for the synthesis of the herbicide quizalofop and quizalofop-p-ethyl, and its production method is generally through cyclization of p-chloro-o-nitroacetoacetanilide under alkaline conditions Obtain 6-chloro-2-hydroxyquinoxaline-4-oxide, and then obtain 6-chloro-2-hydroxyquinoxaline through selective reduction. The reduction methods reported so far mainly include borohydride or alkali metal hydrosulfide and catalytic methods. The borohydride reduction method is easy to operate and has a high yield, but its disadvantage is that the price of the borohydride salt is too high, resulting in high production costs; the sodium sulfide reduction method has low raw material cost, easy operation, and high yield. However, the three indu...

Claims

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Application Information

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IPC IPC(8): C07D241/44
Inventor 周康伦赵国平金劲松凌朵朵胡志国陈克付
Owner ANHUI FENGLE AGROCHEM
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