Preparation method of p-aminophenylacetic acid

Abstract

The invention discloses a preparation method of a p-aminophenylacetic acid, which comprises the following steps of: adding p-nitrophenylacetic acid, ethanol and a catalyst into a pressure reaction kettle in a certain proportion, replacing air in the reaction kettle with nitrogen, feeding hydrogen into the reaction kettle, and controlling a certain pressure and temperature; after the reaction is performed for a period of time, standing the reaction kettle, cooling the obtained product to room temperature, opening the pressure reaction kettle, and extracting 60-80% solvent ethanol through evaporating; carrying out cooling crystallization, filtration and drying on the solvent ethanol so as to obtain a coarse product, and carrying out recrystallization on the coarse product by using ethanol, and carrying out active carbon decoloration on the obtained product so as to obtain white crystalline p-aminophenylacetic acid, wherein the mass ratio of the p-nitrophenylacetic acid, the ethanol to the catalyst is 1:10: (0.02-0.05), the mass concentration of the ethanol is 95%, the mass concentration of the catalyst is 3-8% Pd / attapulgite clay, the reaction pressure is 0.4-0.6 MP, the reaction time is 3-5 hours, and the reaction temperature is 30-60 DEG C. According to the invention, the catalyst is low in cost, less in application amount and convenient for recycling; the method is mild in reaction conditions, energy-saving and environment-friendly; the method is good in reaction selectivity, less in side effects, easy to realize purification, and high in yield; and through taking hydrogen as a raw material, the method is less in pollution, simple in post-processing, and low in production cost.

Description

technical field [0001] The invention relates to a preparation method of p-aminophenylacetic acid. Background technique [0002] p-Aminophenylacetic acid is an important chemical intermediate, commonly used in the synthesis of 3,4-diaminophenylacetic acid, 4-sulfonamidophenylacetic acid, ethyl 4-isocyanatophenylacetic acid, and immunotherapy for the treatment of chronic rheumatoid arthritis Modulator atalide, β-adrenoceptor blocker atenolol, can also be used to prepare azo dyes. Various preparation methods of p-aminophenylacetic acid have been reported in the existing literature, which are summarized as follows: [0003] 1) Using nitrophenylacetic acid as raw material, obtain p-aminophenylacetic acid by reduction with Fe and hydrochloric acid: [0004] [0005] This reaction is a metal reduction method, which requires the use of Fe and hydrochloric acid, and will produce a large amount of waste residue containing iron sludge, which is harmful to the environment. [0006...

AI Technical Summary

Problems solved by technology

However, in this type of method, when Raney nickel is selected as the catalyst, higher temperature and pressure are required, and the requirements for the reaction operating conditions are higher; when Pd / C is selected as the catalyst, the preparation cost of the Pd / C catalyst is relatively high, which is not conducive to cut costs

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