Preparation method of chemical intermediate benzocaine

Abstract

The invention discloses a preparation method of chemical intermediate benzocaine. The preparation method of the chemical intermediate benzocaine comprises the steps: S1, adding 4-nitrobenzoic acid, absolute ethanol, a solid catalyst and a water-carrying agent into a reaction container with a water segregator and performing hot reflux for 1 to 6 hours, wherein the solid catalyst takes magnesium aluminum hydrotalcite as a precursor and modified nanometer bentonite as a carrier, the weight of the precursor is 25 to 45 percent that of the carrier, and the solid catalyst is prepared by grinding and mixing the precursor and the carrier uniformly and calcining at 500 to 700 DEG C for 2 to 4 hours; S2, discharging water out of the water segregator, replenishing the absolute ethanol and continuously performing reflux and water segregation until no water drops occur; S3, after the reaction is finished, filtering when the reaction liquid is hot and putting the filtrate into a hydrogenation kettle to perform hydrogenation reaction; S4, after the hydrogenation is finished, performing heat filtration to remove the catalyst from the system, cooling and filtering under the protection of nitrogen, and drying to obtain the chemical intermediate benzocaine. The preparation method of the benzocaine, provided by the invention, is high in conversion rate; the solid catalyst has high catalytic efficiency and can be repeatedly used, and the catalytic efficiency is not obviously reduced after the catalyst is repeatedly used for 50 times.

Description

technical field [0001] The invention belongs to the field of chemical industry, relates to chemical intermediates, in particular to a preparation method of chemical intermediate benzocaine. Background technique [0002] Benzocaine is a kind of important chemical intermediate, mainly contains two kinds of synthetic methods at present: a kind of method is to take p-nitrobenzoic acid as raw material, take concentrated sulfuric acid or cationic exchange resin as catalyst and dehydrating agent, carry out with ethanol The esterification reaction obtains ethyl p-nitrobenzoate, and then obtains benzocaine through iron powder reduction; another method is to use ethyl p-aminobenzoate as raw material, using thionyl chloride, phosphorus oxychloride and Concentrated sulfuric acid is esterified with ethanol to obtain benzocaine. 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...

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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.