Preparation method for 5-ethyl-5-phenyl barbituric acid

Abstract

The invention provides a preparation method for 5-ethyl-5-phenyl barbituric acid. The method comprises the following steps of: A, adding ethyl acetate into methanol solution of sodium methylate and heating to reflow, then adding a compound diethyl alpha-ethyl-alpha-phenylmalonate, and acting with urea to prepare sodium 5-ethyl-5-phenylbarbiturate; and performing hydrochloric acidification to prepare a rough product of the 5-ethyl-5-phenyl barbituric acid; and B, re-crystallizing the rough product of the 5-ethyl-5-phenyl barbituric acid in ethanol aqueous solution to obtain a finished product of the 5-ethyl-5-phenyl barbituric acid. Compared with the prior art, the preparation method has the advantages of stable process, mild reaction conditions, easiness in control, stable product quality, high yield, easiness and convenience in post-treatment, few three wastes (waste water, waste gas and industrial residues), low production cost and adaptability to industrial production.

Description

technical field [0001] The invention relates to a chemical synthesis process, in particular to a new synthesis process of 5-ethyl-5-phenylbarbituric acid. Background technique [0002] The synthetic method reported in document U.S.Pat, 2358072 mainly uses diethyl phenyl ethyl malonate and thiourea as raw materials, which are obtained by condensation under the catalysis of sodium ethylate, but due to the generation of a large number of by-products, the yield is low. And it is difficult to industrialize production. Anhui Chemical Industry, Volume 33, No. 2 report on the synthesis of phenobarbital, the synthesis method is 52.8g (0.1998mol) diethyl phenyl ethyl malonate and 14g ( 0.2333mol) carbamide was refluxed (80°C), and 85.8g, 6.7% (w / w) (0.0845mol) newly prepared sodium ethoxide solution was added dropwise within 4 hours, but due to the first formation of The sodium salt of phenobarbital, and the sodium ethoxide used in this paper is all converted into the sodium sa...

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Problems solved by technology

[0002] The synthetic method reported in document U.S.Pat, 2358072 mainly uses diethyl phenyl ethyl malonate and thiourea as raw materials, which are obtained by condensation under the catalysis of sodium ethylate, but due to the generation of a large number of by-products, the yield is low. and difficult to industrialize

Anhui Chemical Industry, Volume 33, No. 2 report papers on the synthesis of phenobarbital, the synthesis method is 52.8g (0.1998mol) diethyl phenyl ethyl malonate and 14g ( 0.2333mol) carbamide was refluxed (80°C), and 85.8g, 6.7% (w / w) (0.0845mol) newly prepared sodium ethoxide solution was added dropwise within 4 hours, but due to the first formation of The sodium salt of phenobarbital, and the sodium ethoxide used in this paper is all converted into the sodium salt of phenobarbital, and the conversion rate of α-ethyl-α-phenylmalonate diethyl ester is only 42% at most , and this reaction can only be carried out under the catalysis of sodium ethylate, so the disadvantages of this method are that the product yield is low, the efficiency is low, many by-products need to be extracted with xylene, the energy consumption is high, and the sodium ethylate in ethanol The content requirements are also high, the three wastes are more, and the cost is high