Preparation method of ethyl-4-dimethylaminobenzoate intermediate benzocaine

A technology of ethyl dimethylaminobenzoate and nitrobenzoic acid, which is applied in the field of organic matter preparation, can solve the problems of equipment corrosion, poor color, environmental pollution, etc., and achieve the effect of easy operation

Inactive Publication Date: 2016-04-13
浙江优创材料科技股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Both methods have the problem of producing a large amount of waste acid, which not only pollutes the environment, but also easily corrodes the equipment, and the obtained product has problems such as low yield and poor color.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] The preparation method of the present embodiment 1 benzocaine, the specific steps are as follows: in a 250mL four-necked bottle equipped with stirring and a thermometer, add 33.4g of 4-nitrobenzoic acid, 9.3g of absolute ethanol, 1g of neodymium trioxide 150mL of toluene, heated to reflux for 3h at a stirring speed of 350rpm, and began to separate water. After water separation, 2 g of absolute ethanol was added, and after reflux reaction for 1 hour, after water separation, the solid catalyst was removed by hot filtration, and the filtrate was put into a 250 mL hydrogenation reaction kettle. Then add 5%Pd / C1.9g, and carry out hydrogenation reaction at 80-100°C for 2h. After removing the catalyst by hot filtration, cool to room temperature under the protection of nitrogen, and filter and dry to obtain 30.4 g of white benzocaine powder (GC content ≥ 99.5%).

Embodiment 2

[0025] Using the same feeding method and feeding amount as in Example 1, and applying the recycled neodymium trioxide and Pd / C catalyst, 30.3 g of benzocaine powder (GC content ≥ 99.5%) was obtained at the end of the reaction.

Embodiment 3

[0027] Add 267.2g of 4-nitrobenzoic acid, 74.4g of absolute ethanol, 8g of neodymium trioxide, and 1.2L of toluene into a 2L four-necked flask equipped with stirring and a thermometer, heat and reflux for 4 hours at a stirring speed of 350rpm, and start to separate water. After water separation, 16 g of absolute ethanol was added, and after reflux reaction for 2 hours, after water separation, the solid catalyst was removed by heat filtration, and the filtrate was put into a 2L hydrogenation reactor. Then add 5% Pd / C15.2g, and carry out hydrogenation reaction at 80-100°C for 2h. After removing the catalyst by hot filtration, cool to room temperature under the protection of nitrogen, and filter and dry to obtain 245.8 g of white benzocaine powder (GC content ≥ 99.5%).

[0028] The preparation method of a kind of p-dimethylaminobenzoic acid ethyl ester intermediate benzocaine (4-aminobenzoic acid ethyl ester) of the present invention, adds 4-nitrobenzoic acid, no Water ethanol,...

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PUM

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Abstract

The present invention relates to a preparation method of ethyl-4-dimethylaminobenzoate intermediate benzocaine (ethyl-4-aminobenzoate). The specific steps are as follows: adding 4- nitrobenzoic acid, absolute ethyl alcohol, a solid catalyst and a water carrying agent into a reaction vessel with a water separator, wherein the reaction vessel is equipped with the water separator, a reflux condenser and a thermometer; heating, refluxing to separate water, and reacting to no stratification; filtering the reaction solution while hot, adding the reaction solution into a hydrogenation reactor, conducting a hydrogenation reaction by directly using Pd / C until hydrogen-absorption of the system stops, and then insulating for 1 h; filtering, cooling, and precipitating a white solid product of benzocaine with content of more than 99.5%. The method is a pure green route, not only avoids production of a lot of waste acid in the esterification process, but also recycles the solvent and catalyst. The method has the advantages of simple method, mild conditions, continuous two-step reaction, and good prospects in the industry.

Description

technical field [0001] The invention relates to the technical field of organic matter preparation, in particular to a preparation method of benzocaine (ethyl 4-aminobenzoate), an intermediate of ethyl p-dimethylaminobenzoate. Background technique [0002] Benzocaine (ethyl 4-aminobenzoate) is a colorless rhomboid crystal, 1g of this product is soluble in about 2500ml of water, 5ml of ethanol, 2ml of chloroform, 4ml of ether or 30-50ml of almond oil and olive oil, and is also soluble in dilute acid. Stable in air, odorless, bitter taste. This product has a wide range of uses. It can be used as a local anesthetic to relieve pain on wounds, ulcers and hemorrhoids. [0003] For the synthesis of benzocaine, there are mainly two production methods at present. A method is to take p-nitrobenzoic acid as raw material, use concentrated sulfuric acid or cation exchange resin as catalyst and dehydrating agent, carry out esterification reaction with ethanol to obtain ethyl p-nitrobenz...

Claims

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Application Information

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IPC IPC(8): C07C227/04C07C229/60
CPCY02P20/584C07C227/04C07C201/12C07C229/60C07C205/57
Inventor 吴佳春朱晓东施根祥
Owner 浙江优创材料科技股份有限公司
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