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The preparation method of 1-alkyl-3-difluoromethyl-5-hydroxypyrazole

A technology of difluoromethyl and hydroxypyrazole is applied in the field of preparation of 1-alkyl-3-difluoromethyl-5-hydroxypyrazole, and can solve the problems of low yield, difficulty in obtaining reactants and the like

Active Publication Date: 2015-11-25
BAYER CROPSCIENCE AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These methods described in the prior art cannot be realized economically due to low yields and / or difficulties in obtaining the required reactants on an industrial scale

Method used

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  • The preparation method of 1-alkyl-3-difluoromethyl-5-hydroxypyrazole
  • The preparation method of 1-alkyl-3-difluoromethyl-5-hydroxypyrazole
  • The preparation method of 1-alkyl-3-difluoromethyl-5-hydroxypyrazole

Examples

Experimental program
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Effect test

Embodiment 1

[0026] Example 1: 1-methyl-3-difluoromethyl-5-hydroxy-1H-pyrazole

[0027]

[0028] First, 166 g (1 mol) of ethyl difluoroacetoacetate was added to 500 ml of methyl tert-butyl ether, and then 140 g of formic acid was added. After the mixture had cooled to 5° C., 119 g of methylhydrazine were added as a 40% aqueous solution. The mixture was stirred for an additional 20 hours at a temperature of 22°C. Separate the phases, wash the organic phase with 200ml water, and wash with MgSO 4 dry. After removal of the solvent under reduced pressure, 148 g of the product are obtained in the form of a yellow solid with a melting point of 133° C. and a purity of 95%. The yield was 95%.

Embodiment 2

[0029] Example 2: 1-Methyl-3-difluoromethyl-5-hydroxy-1H-pyrazole

[0030] First, 166 g (1 mol) of ethyl difluoroacetoacetate was added to 500 ml of methyl tert-butyl ether, and then 60 g of acetic acid was added. After the mixture had cooled to 5° C., 119 g of methylhydrazine were added as a 40% aqueous solution. The mixture was stirred for an additional 20 hours at a temperature of 22°C. Separate the phases, wash the organic phase with 200ml water, and wash with MgSO 4 dry. After removal of the solvent under reduced pressure, 140 g of the product are obtained in the form of a yellow solid with a melting point of 133° C. and a purity of 96%. The yield was 91%.

Embodiment 3

[0031] Example 3. Reaction according to WO2007 / 013536

[0032] First 166 g (1 mol) of ethyl difluoroacetoacetate were added to 400 ml of acetic acid. The mixture was cooled to 5°C and 119 g of methylhydrazine were added as a 40% aqueous solution. The mixture was stirred for an additional 20 hours at a temperature of 22°C. LC-MC showed 55 area % product, 15 area % 2-methyl-3-difluoromethyl-5-hydroxy-1H-pyrazole isomer, and 30 area % various by-products.

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Abstract

The present invention relates to a process for preparing 1-alkyl-3-difluoromethyl-5-hydroxypyrazoles, which are valuable intermediates for the production of fungicides.

Description

technical field [0001] The present invention relates to a process for the preparation of 1-alkyl-3-difluoromethyl-5-hydroxypyrazoles, which are valuable intermediates for the preparation of fungicides. technical background [0002] 1-Alkyl-3-difluoromethyl-5-hydroxypyrazoles are important units for the preparation of active crop protection ingredients, which are usually prepared by reacting β-ketoesters with alkylhydrazines. This usually forms two regioisomers, thus resulting in reduced yields. For example, Takahashi et al. in US2005 / 256004A1 describe the reaction of difluoroacetoacetate with monomethylhydrazine (MMH) in the presence of concentrated HCl in ethanol to give 3-difluoromethyl-1-methyl-1H - The yield of pyrazol-5-ol was only 33.3%. [0003] Another method for the preparation of 1-alkyl-3-polyfluoroalkyl-5-hydroxypyrazoles is described by Hamper et al. in J. Fluorine Chemistry, 1990, Vol. 48, pp. 123-131. However, the use of perfluoroalkylacetylene esters as ra...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D231/20
CPCC07D231/20A01N43/56
Inventor S·帕斯诺克M·穆勒N·路易
Owner BAYER CROPSCIENCE AG