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Synthesis method of 1-methyl-5-hydroxy pyrazole

A technology of hydroxypyrazole and synthetic method, applied in the direction of organic chemistry, etc., can solve the problems of easy moisture absorption, low purity, poor selectivity, etc.

Active Publication Date: 2021-03-12
ZHEJIANG UNIV OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0009] An important problem that plagues the synthesis of 1-methyl-5-hydroxypyrazole is how to obtain 1-methyl-5-hydroxypyrazole with better quality through reasonable post-treatment means, because if the selectivity is poor and the purity is not high, It is difficult to obtain solid 1-methyl-5-hydroxypyrazole
Liu Yingxian mentioned in the "Synthesis of High-efficiency Herbicide Pyrazenone" that n-butanol was used as the reflux water-carrying reagent in the post-treatment method, the effect was not ideal, the yield was low, the product was not easy to dry, easy to absorb moisture and exist by-product

Method used

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  • Synthesis method of 1-methyl-5-hydroxy pyrazole
  • Synthesis method of 1-methyl-5-hydroxy pyrazole
  • Synthesis method of 1-methyl-5-hydroxy pyrazole

Examples

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Embodiment 1

[0032] At room temperature, add 6.49g (30mmol) of diethyl ethoxymethylenemalonate to a 100mL round bottom flask, weigh 2.34g (33mmol) of tetrahydropyrrole and slowly drop it into the flask, then react at 25°C 3 hours, take by weighing methylhydrazine aqueous solution (40%) 4.49g (methylhydrazine 39mmol) slowly dropwise in the above-mentioned solution, reaction temperature is controlled at 25 ℃, reaction time is 5 hours, then slowly add dropwise 15mL concentrated hydrochloric acid (mass Fraction 37%), a yellow solid precipitated out, then dissolved, and the solution turned into a yellow clear solution. The round bottom flask was then heated to reflux in an oil bath at 100°C for 6 hours. After cooling to room temperature, use 30% mass fraction sodium hydroxide solution to adjust the pH of the reaction solution to be neutral, add NaCl solid until the solution is saturated, use n-butanol to extract the aqueous solution, separate the layers, take the organic layer, and remove most ...

Embodiment 2

[0034]At room temperature, add 10.81g (50mmol) of diethyl ethoxymethylenemalonate to a 100mL round bottom flask, weigh 4.27g (60mmol) of tetrahydropyrrole and slowly drop it into the flask, then react at 30°C For 3 hours, weigh 7.49 g of methylhydrazine aqueous solution (40%) (65 mmol of methylhydrazine) and slowly add it dropwise to the above solution. During the process, a yellow solid precipitated out, then dissolved, and the solution turned into a yellow clear solution. The round bottom flask was then heated to reflux in an oil bath at 110°C for 6 hours. After being cooled to room temperature, adjust the pH of the reaction solution to be neutral with 30% mass fraction sodium hydroxide solution, add Na 2 SO 4 Solid until the solution is saturated, extract the aqueous solution with butyl acetate, separate the layers, take the organic layer, and distill off most of the butyl acetate under reduced pressure, then filter the precipitated residual Na 2 SO 4 , the filtrate was...

Embodiment 3

[0036] At room temperature, add 11.89g (55mmol) of diethyl ethoxymethylenemalonate to a 100mL round bottom flask, weigh 5.12g (72mmol) of tetrahydropyrrole and slowly drop it into the flask, then react at 35°C After 2 hours, weigh 8.24 g of methylhydrazine aqueous solution (40%) (72 mmol of methylhydrazine) and slowly add it dropwise to the above solution. The reaction temperature was controlled at 35° C., and the reaction time was 4 hours. A yellow solid precipitated out during the addition, and then dissolved, and the solution turned into a yellow clear solution. The round bottom flask was then heated to reflux in an oil bath at 120°C for 6 hours. After cooling to room temperature, use 30% mass fraction sodium hydroxide solution to adjust the pH of the reaction solution to be neutral, add NaCl solid until the solution is saturated, extract the aqueous solution with isopropyl ether, separate the layers, take the organic layer, and remove most of it by distillation under reduc...

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Abstract

The invention relates to a synthesis method of 1-methyl-5-hydroxy pyrazole, which comprises the following steps of dropwisely adding tetrahydropyrrole into diethyl ethoxymethylene malonate at room temperature, and reacting at 15-80 DEG C for 2-6 hours to obtain a reaction solution A containing a compound represented by a formula (II), dropwise adding a methylhydrazine aqueous solution into the reaction solution A, and reacting at 15-80 DEG C for 2-6 hours to obtain a reaction solution B containing a compound shown as a formula (III), dropwise adding an acidic solution into the reaction solution B, and heating and refluxing for 4-8 hours at 90-120 DEG C after dropwise adding to obtain a reaction solution C containing a compound shown as a formula (IV), and carrying out post-treatment on thereaction solution C to obtain the target compound 1-methyl-5-hydroxy pyrazole. The synthesis method has the advantages of higher activity, higher reaction rate, better selectivity, higher total yield, cheap and accessible raw materials and simple post-treatment, and can obtain the solid 1-methyl-5-hydroxy pyrazole with higher purity.

Description

technical field [0001] The invention relates to the field of organic synthesis, in particular to a method for synthesizing a pesticide intermediate 1-methyl-5-hydroxypyrazole with diethyl ethoxymethylene malonate as a raw material. [0002] technical background [0003] 1-methyl-5-hydroxypyrazole (CAS: 33641-15-5), its chemical structure is as follows: [0004] [0005] 1-Methyl-5-hydroxypyrazole is an important pesticide intermediate and an important raw material for the synthesis of benzoylpyrazoles. As a p-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor herbicide, benzoylpyrazole compounds have the advantages of high efficiency, high selectivity, and low toxicity. The high-efficiency new cornfield herbicide fenflumezone stands out as one of the best, and its market is further developing and expanding. [0006] The synthesis of 1-methyl-5-hydroxypyrazole mainly contains the following two types: [0007] (1) Cyclization of α,β-unsaturated carbonyl compounds and hydr...

Claims

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Application Information

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IPC IPC(8): C07D231/20
CPCC07D231/20
Inventor 王益锋韩宏特许丹倩徐振元
Owner ZHEJIANG UNIV OF TECH
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