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Method for synthesizing p-methoxybenzoic acid

A technology of methoxybenzoic acid and p-hydroxybenzoic acid, which is applied in the field of industrial synthesis of p-methoxybenzoic acid, can solve the problems of high reaction temperature, extended production cycle, and high preparation cost, and achieve high product yield and safety Good performance and low cost

Inactive Publication Date: 2017-02-01
BEILI CHEM ZHANGJIAGANG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The disadvantages are: 1. Dimethyl sulfate is highly toxic; 2. A large amount of waste acid and waste water will be produced during production
[0003] Although Weidlich et al. (Applied Organometallic Chemistry, Volume 26, Issue6Pages 293-300) disclosed the use of dimethyl carbonate as a methylating reagent, p-hydroxybenzoic acid was used as a starting material to synthesize p-methoxybenzoic acid, but due to carbonic acid The activity of dimethyl ester is not high, and this reaction needs to use a special catalyst (CAS: 917772-88-4). It consumes a lot of energy, prolongs the production cycle, reduces the production efficiency of the reaction device, and easily leads to yellowing of the product, which affects the appearance of the product

Method used

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  • Method for synthesizing p-methoxybenzoic acid
  • Method for synthesizing p-methoxybenzoic acid

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Experimental program
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Effect test

Embodiment 1

[0026] Dissolve 13.8g of p-hydroxybenzoic acid, 13.5g of dimethyl carbonate, and 0.16g of tetrabutylammonium bromide in 150ml of methanol. After dissolving, pump it into the microreactor with a flow rate of 3mL / min and a reaction pressure of 5MPa. Heat to 120°C, residence time 20min, after about 1.5 hours, the reaction was completed, part of the methanol was recovered from the feed liquid, the feed liquid was cooled to room temperature, filtered, and dried to obtain 12.9 g of a white solid with a yield of 85% and a purity of 98%.

Embodiment 2

[0028] Dissolve 13.8g of p-hydroxybenzoic acid, 13.5g of dimethyl carbonate, and 0.16g of tetrabutylammonium bromide in 150ml of methanol. After dissolving, pump it into the microreactor with a flow rate of 3mL / min and a reaction pressure of 5MPa. Heat to 130°C, residence time 20min, the reaction ended after about 1.5 hours, part of the methanol was recovered from the feed liquid, the feed liquid was cooled to room temperature, filtered, and dried to obtain 14.0 g of white solid with a yield of 92% and a purity of 99%.

Embodiment 3

[0030] Dissolve 13.8g of p-hydroxybenzoic acid, 13.5g of dimethyl carbonate, and 0.16g of tetrabutylammonium bromide in 150ml of methanol. After dissolving, pump it into the microreactor with a flow rate of 3mL / min and a reaction pressure of 5MPa. Heat to 140°C, residence time 20min, after about 1.5 hours, the reaction was completed, part of the methanol was recovered from the feed liquid, the feed liquid was cooled to room temperature, filtered, and dried to obtain 13.2 g of white solid with a yield of 87% and a purity of 98%.

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Abstract

The invention discloses a method for synthesizing p-methoxybenzoic acid. The method comprises the following step: by taking a micro reactor as reaction equipment, and tetrabutyl ammonium bromide as a catalyst, performing etherification on p-hydroxybenzoic acid and dimethyl carbonate, thereby obtaining p-methoxybenzoic acid. According to the method, the yield is high, the aftertreatment is simple, and continuous production can be achieved.

Description

technical field [0001] The invention belongs to the field of fine chemicals, relates to the synthesis of commonly used chemicals, in particular to the industrial synthesis of p-methoxybenzoic acid. Background technique [0002] P-methoxybenzoic acid is an important cosmetic additive and pharmaceutical intermediate. The traditional process is to obtain p-hydroxybenzoic acid as a raw material by methylating it with dimethyl sulfate under alkaline conditions, and then acidifying it with sulfuric acid. The disadvantages are: 1. Dimethyl sulfate is highly toxic; 2. A large amount of waste acid and waste water will be produced during production. [0003] Although Weidlich et al. (Applied Organometallic Chemistry, Volume 26, Issue6Pages 293-300) disclosed the use of dimethyl carbonate as a methylating reagent, p-hydroxybenzoic acid was used as a starting material to synthesize p-methoxybenzoic acid, but due to carbonic acid The activity of dimethyl ester is not high, and this reac...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/367C07C65/21
CPCC07C51/367C07C65/21
Inventor 程文峰任春和徐晓东颜廷帅张雯君杨巧梅
Owner BEILI CHEM ZHANGJIAGANG
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