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Preparation method of 3-methyl-4-nitrobenzoic acid

A technology of nitrobenzoic acid and methyl, which is applied in the field of preparation of antihypertensive drug telmisartan intermediates, can solve the problems of low technical selectivity and low conversion rate, and achieve stable reaction, easy control, and conditions mild effect

Inactive Publication Date: 2021-10-08
安徽江泰新材料科技有限公司
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Problems solved by technology

[0003] However, these technologies all have problems such as low selectivity and low conversion rate.

Method used

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  • Preparation method of 3-methyl-4-nitrobenzoic acid

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Embodiment Construction

[0012] (1) Preparation of 3-methyl-4-nitrobenzoic acid

[0013] 1. Add 300mL of acetonitrile into the photoreactor (with a filter tube with a filter wavelength less than 380nm), blow in oxygen from below, then add 5g of 2,4-dimethylnitrobenzene, 380mg of catalyst hematoporphyrin, and 2g of NiO , Turn on the high-pressure mercury lamp, react at 30°C for 5 hours, filter, spin the filtrate to recover the solvent acetonitrile, add water, stir to dissolve, acidify to pH=3.8, filter to obtain 3.95g of 3-methyl-4-nitrobenzoic acid, purity 96.7 %.

[0014] 2. Add 300mL of acetonitrile into the photoreactor (with a filter tube with a filter wavelength less than 380nm), blow in oxygen from below, then add 5g of 2,4-dimethylnitrobenzene, and 395mg of catalyst hematoporphyrin monomethyl ether , NiO 2g, turn on the high-pressure mercury lamp, react at 30°C for 5h, filter, spin the filtrate to recover the solvent acetonitrile, pour the residue into water, acidify to pH=3.8, and filter to o...

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Abstract

The invention relates to a preparation method of 3-methyl-4-nitrobenzoic acid, which comprises the following steps: by taking 2,4-dimethyl nitrobenzene as an initial raw material, carrying out selective oxidation on 4-position methyl to generate 3-methyl-4-nitrobenzoic acid. Compared with the prior art, the method is characterized in that the oxidation comprises the steps of introducing oxygen under stirring and illumination in the presence of an acetonitrile solvent and a catalyst, conducting reacting for 5 hours at the temperature of 30 DEG C, conducting filtering after the reaction is finished, taking filtrate, carrying out rotary evaporation to recover an acetonitrile solvent, adding water, conducting acidifying until the pH is about 3.8, and conducting filtering to obtain 3-methyl-4-nitrobenzoic acid. The conversion rate of 2,4-dimethyl nitrobenzene is greater than or equal to 98%, and the yield of the 3-methyl-4-nitrobenzoic acid is about 65%. The method is mild in condition, stable in reaction, stable in quality, simple in process and convenient to operate.

Description

1. Technical field [0001] The invention relates to a preparation method of an antihypertensive drug telmisartan intermediate, in particular to a preparation method of 3-methyl-4-nitrobenzoic acid. 2. Background technology [0002] 3-Methyl-4-nitrobenzoic acid is an important intermediate in the synthesis of antihypertensive drug telmisartan. There are few reports on its synthetic methods in the literature, and most of the reported synthetic routes start with m-toluic acid. 2,4-dimethylnitrobenzene is also selected as the starting material to generate 3-methyl-4-nitrobenzoic acid through the selective oxidation of the 4-methyl group. For the oxidation reaction, dilute nitric acid can be used as the oxidant, and air can also be used as the oxidant under the action of the cobalt acetate / butanone catalytic system in the acetic acid medium. At 85°C and the air pressure is 0.5MPa, the highest conversion rate of the reaction is 58%. 3- The selectivity of methyl-4-nitrobenzoic acid...

Claims

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Application Information

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IPC IPC(8): C07C201/12C07C205/57
CPCC07C201/12C07C205/57
Inventor 朱益民
Owner 安徽江泰新材料科技有限公司
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