Green preparation process of benzocaine

Abstract

The invention discloses a green preparation process of benzocaine. The process comprises the steps that p-nitrobenzoic acid and ethanol are subjected to esterification under the catalysis of concentrated sulfuric acid to obtain ethyl p-nitrobenzoate; ethyl p-nitrobenzoate is subjected to catalytic hydrogenation to obtain the benzocaine, wherein catalytic hydrogenation reaction is performed in water; the catalytic hydrogenation reaction temperature is 90 to 110 DEG C; the catalytic hydrogenation reaction pressure is 0.2 to 1.0MPa; the use quantity of water is 3 to 7 times of the weight of ethylp-nitrobenzoate; the weight ratio of ethyl p-nitrobenzoate to a catalyst is (1:0.001)-(1:0.1); the catalyst is a Pd / C catalyst with the mass fraction being 3 to 10 weight percent. Through the catalytic hydrogenation reaction, the use of organic solvents is avoided, so that the whole benzocaine preparation becomes a green process; the proper use quantity of water is selected, so that high reactionyield and product purity can be obtained.

Description

Technical field [0001] The invention belongs to the technical field of fine chemicals, and specifically relates to a green preparation process of benzocaine (ethyl para-aminobenzoate). Background technique [0002] Benzocaine (Benzocaine) is another name for ethyl para-aminobenzoate. It can be used as a local anesthetic for wounds, ulcers and hemorrhoids to relieve itching and pain. It can also be used as a drug intermediate; UV absorbers can be used It is mainly used in sunscreen and tanning cosmetics. It is chemically stable to light and air, safe to the skin, and has the ability to form a film on the skin. At the same time, it can be used as an intermediate for other ultraviolet absorbers. [0003] Chinese patent document CN105315168A discloses a green preparation process of N-(4-ethoxycarbonylphenyl)-N'-methyl-N'-phenylformamidine intermediate (also known as benzocaine), which Using p-nitrobenzoic acid as a raw material, it is firstly esterified with ethanol under the catalysi...

AI Technical Summary

Problems solved by technology

[0005] For the catalytic hydrogenation reaction, this document does not improve it, and still adopts the prior art, and the existing catalytic hydrogenation reaction is all performed in an organic solvent capable of dissolving benzocaine (such as ethanol, toluene, etc.) and since the melting point of benzocaine is only about 90°C, the existing catalytic hydrogenation reaction temperature is generally around 80°C

[0006] And because benzocaine is insoluble in water, therefore, prior art all does not adopt water as the solvent of this catalytic hydrogenation reaction