Preparation method of oxadiazon intermediate 2, 4-dichloro-5-isopropoxyphenylhydrazine

A technology for isopropoxyphenylhydrazine and intermediates, which is applied in the field of preparing 2,4-dichloro-5-isopropoxyphenylhydrazine, can solve the problems of difficult waste water treatment, expensive raw materials, difficult recovery and the like

Active Publication Date: 2021-04-20
湖南兴同化学科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] In order to overcome the above problems, the present invention aims to provide a novel preparation method of 2,4-dichloro-5-isopropoxyphenylhydrazine to solve the problems of high safety risks, expensive raw materials and difficult recovery in the existing preparation process. , waste water is difficult to treat and many other problems

Method used

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  • Preparation method of oxadiazon intermediate 2, 4-dichloro-5-isopropoxyphenylhydrazine
  • Preparation method of oxadiazon intermediate 2, 4-dichloro-5-isopropoxyphenylhydrazine
  • Preparation method of oxadiazon intermediate 2, 4-dichloro-5-isopropoxyphenylhydrazine

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Embodiment 1

[0030] Add 200 g of 2,4-dichloro-5-isopropoxyaniline toluene solution with an internal standard content of 35% into a 500 mL four-neck flask with a condenser tube inserted, slowly pour 42 g of 30% hydrochloric acid at room temperature, and continue After stirring for 0.5h, add 33.5g of potassium cyanate, then slowly raise the temperature to 100-105°C, reflux for 2h, and trace the raw material 2,4-dichloro-5-isopropoxyaniline by gas chromatography <1%, the reaction is over , cooling to obtain an intermediate (phenyl urea), to be added sodium hypochlorite alkali solution.

[0031] When the temperature drops to 20-25°C, start to drop 372g of sodium hypochlorite alkali solution mixed in advance (the molar ratio of urea, sodium hypochlorite, and alkali is 1:1.25:2.6), and control the temperature of the whole process not to exceed 25°C. After completion, keep the reaction for 40 minutes, then slowly raise the temperature to 80-85°C, continue the heat preservation reaction for 1 hour...

Embodiment 2

[0034] The preparation of phenylurea (intermediate) is the same as in Example 1, and the second step of degradation and rearrangement process replaces sodium hypochlorite with sodium hypobromite to obtain 2,4-dichloro-5-isopropoxyphenylhydrazine with a purity of 98.8%. The two-step yield of 2,4-dichloro-5-isopropoxyaniline to phenylhydrazine is 92.69%.

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Abstract

The invention provides a preparation method of a herbicide oxadiazon intermediate 2, 4-dichloro-5-isopropoxy phenylhydrazine, which comprises the following steps: by taking a toluene solution of 2, 4-dichloro-5-isopropoxy aniline as a raw material, stirring to form a salt under an acidic condition, reacting with cyanate at a certain temperature to generate urea, degrading and rearranging by Hofmann in an alkaline environment, filtering, after recovering a solvent at normal pressure, taking 2, 4-dichloro-5-isopropoxy phenylhydrazine as a raw material, adding chloroform for extraction, and obtaining a chloroform solution of the 2, 4-dichloro-5-isopropoxy phenylhydrazine which can be directly used for an acylation process to synthesize the oxadiazon key intermediate 2, 4-dichloro-5-isopropoxy phenylhydrazine. According to the method disclosed by the invention, a complicated tin recovery process caused by reduction of diazonium salt by stannous chloride in a traditional synthesis process is effectively avoided, and generation of a large amount of high-salt wastewater in a recovery section is avoided; on the other hand, alkalization operation is avoided, solid materials are not added, the labor intensity is greatly reduced, and the production efficiency is effectively improved.

Description

technical field [0001] The invention relates to the technical field of organic synthesis, in particular to a method for preparing 2,4-dichloro-5-isopropoxyphenylhydrazine. Background technique [0002] Oxadiazone is a high-efficiency broad-spectrum herbicide for controlling various annual monocotyledonous and dicotyledonous weeds. Its structural formula is: [0003] [0004] Both 2,4-dichloro-5-isopropoxyaniline and 2,4-dichloro-5-isopropoxyphenylhydrazine are key intermediates for the synthesis of oxadiazone. [0005] In the prior art, the synthetic method of 2,4-dichloro-5-isopropoxyphenylhydrazine generally needs 2,4-dichloro-5-isopropoxyaniline to generate diazonium salt through diazotization, and then The 2,4-dichloro-5-isopropoxyphenylhydrazine hydrochloride was prepared by reduction with a reducing agent, and then the product 2,4-dichloro-5-isopropoxyphenylhydrazine was obtained by alkalinization. The thermal stability of the diazonium salt in the diazotization p...

Claims

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Application Information

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IPC IPC(8): C07C241/02C07C243/22
Inventor 廖丽莎朱有为熊运畅李华轩甘娟王宇
Owner 湖南兴同化学科技有限公司
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