Preparation method of pyrazole type herbicide intermediate 1-methyl-5-hydroxypyrazole

A technology of hydroxypyrazole and methyl, which is applied in the field of preparation of pyrazole herbicide intermediates, can solve the problems of unfavorable large-scale production, lower yield, poor selectivity, etc., and achieve easy recovery, low price, high yield and purity Effect

Active Publication Date: 2021-03-30
PAPANNA BEIJING TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] However, in this method, the reaction selectivity of the intermediate product and methylhydrazine ring closure is relatively poor, resulting in the final production of a large amount of isomer 1-methyl-4 hydroxypyrazole, thereby reducing the yield; in addition, the process used The corrosiveness of the acetic anhydride and its by-products is strong, difficult to recycle, and the consumption of triethyl orthoformate (or methyl ester) is large and the price is more expensive, which is not conducive to large-scale industrial production

Method used

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  • Preparation method of pyrazole type herbicide intermediate 1-methyl-5-hydroxypyrazole
  • Preparation method of pyrazole type herbicide intermediate 1-methyl-5-hydroxypyrazole
  • Preparation method of pyrazole type herbicide intermediate 1-methyl-5-hydroxypyrazole

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Experimental program
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Effect test

Embodiment 1

[0036] This embodiment provides a method for preparing a pyrazole herbicide intermediate 1-methyl-5-hydroxypyrazole, comprising:

[0037] (1) In a 250ml four-neck flask equipped with a mechanical stirrer, a thermometer, and a condenser tube, add 50g of solvent toluene, 16.1g of DMF (N,N-dimethylformamide) and 27.8g of alkylating agent dimethyl sulfate Add 26.4g (0.2mol) of dimethyl malonate dropwise at 70°C with stirring, drop the temperature to 50°C and add 30.24g (0.24mol) of N,N-diisopropylethylamine dropwise, the dropwise addition is completed within 2 hours ; Insulated at 60°C for 5 hours, and post-processed to obtain compound (2);

[0038] (2) Cool the toluene solution containing compound (2) to 0° C., add 21.9 g of methylhydrazine (content 42%, 0.2 mol), and keep warm for 4 hours to carry out cyclization reaction;

[0039] After treatment, add 56g of sulfuric acid (content 70%, 0.4mol) and heat up to 70°C to react for 8 hours, add alkali to neutralize and remove toluen...

Embodiment 2

[0041] This embodiment provides a method for preparing a pyrazole herbicide intermediate 1-methyl-5-hydroxypyrazole, comprising:

[0042] (1) In a 250ml four-necked flask equipped with a mechanical stirrer, a thermometer, and a condenser, add 60g of dichloroethane as a solvent, 16.1g of DMF and 27.8g of dimethyl sulfate, stir and raise the temperature at 70°C and add dimalonate di 26.4g (0.2mol) of methyl ester, drop the temperature to 50°C and add 24.24g (0.24mol) of triethylamine dropwise, the dropwise addition is completed within 2h, keep warm at 50°C for 5h to obtain compound (2);

[0043] (2) Cool the reaction solution containing compound (2) to 0°C and add 21.9 g of methylhydrazine (content 42%, 0.2 mol) for 4 hours of reaction;

[0044] After treatment, add 56g of sulfuric acid (content 70%, 0.4mol) and heat up to 65°C for 8 hours, add alkali to neutralize, remove the solvent, add 40g of ethanol for beating and filter, and the filtrate is precipitated to obtain 18.6g of...

Embodiment 3

[0046] This embodiment provides a method for preparing a pyrazole herbicide intermediate 1-methyl-5-hydroxypyrazole, comprising:

[0047] (1) In a 250ml four-necked bottle equipped with mechanical stirring, a thermometer, and a condenser, add 60g of dichloroethane, 16.1g of DMF and 27.8g of dimethyl sulfate, stir and raise the temperature at 70°C, and add dimethyl malonate dropwise 26.4g (0.2mol) of ester, cooled to 50°C and added dropwise 24.24g (0.24mol) of triethylamine, the dropwise addition was completed within 2h, kept at 60°C for 5h and treated to obtain compound (2);

[0048](2) cooling the ethylene dichloride solution containing compound (2) to -5°C, adding hydrazine hydrate 12.5g (content 80%, 0.2mol), adding methylating reagent dimethyl sulfate 27.72g ( 0.22mol), insulation reaction 3 hours after adding;

[0049] Add 56g of sulfuric acid (content 70%, 0.4mol) and heat up to 70°C for 6 hours, add alkali to neutralize and remove the solvent, add 40g of ethanol to bea...

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Abstract

The invention belongs to the technical field of preparation of pyrazole type herbicide intermediates, and particularly relates to a preparation method of a pyrazole type herbicide intermediate 1-methyl-5-hydroxypyrazole. The preparation method of the 1-methyl-5-hydroxypyrazole comprises the following steps: (1) in the presence of alkali, enabling dimethyl malonate of a compound (1) to react with aformamide compound and an alkylation reagent in a solvent to generate a compound (2); and (2) carrying out cyclization reaction on the obtained compound (2) and methylhydrazine / hydrazine hydrate in asolvent, and carrying out hydrolysis and decarboxylation by using an acid to obtain a compound (3). According to the method, DMF, an alkylation reagent and the compound (1) react to obtain the compound (2), the obtained compound (2) is good in selectivity when being subjected to ring-closure reaction with methylhydrazine (or hydrazine hydrate), and a target product compound (3) with higher yieldand purity can be obtained. Moreover, the raw materials used in the synthesis method disclosed by the invention are relatively weak in corrosivity, easy to recover and relatively low in price, so thatindustrial production is facilitated.

Description

technical field [0001] The invention belongs to the technical field of preparation of pyrazole herbicide intermediates, in particular to a preparation method of pyrazole herbicide intermediate 1-methyl-5-hydroxypyrazole. Background technique [0002] Fenpyrazone is a very effective herbicide. It is the first benzopyrazolone herbicide developed by BASF. It also belongs to the inhibitor of p-hydroxyphenylpyruvate dioxygenase (HPPD) It has a good control effect on weeds resistant to glyphosate, triazines, acetolactate synthase (ALS) inhibitors and acetyl-CoA carboxylase inhibitors, and can control corn crops worldwide. major grass and broadleaf weeds. Therefore, the research on the synthesis of phenylpyrazoles has received extensive attention. [0003] The benzopyrazoles are usually prepared from the intermediate 1-methyl-5-hydroxypyrazole. At present, the preparation methods of 1-methyl-5-hydroxypyrazole reported at home and abroad are as described in the prior art CN105218...

Claims

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Application Information

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IPC IPC(8): C07D231/20
CPCC07D231/20
Inventor 邢文龙付仁季
Owner PAPANNA BEIJING TECH
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