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Preparation method of 5-methyl-5-phenylbarbituric acid

A technology of phenylbarbituric acid and diethyl phenylmalonate, applied in the field of preparation of 5-methyl-5-phenylbarbituric acid, can solve the problem of difficult industrial production, high content requirements, Low product yield and other problems, to achieve the effect of stable product quality, high yield and simple operation

Inactive Publication Date: 2019-07-12
SHANDONG XINHUA PHARMA CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The existing synthetic methods reported in related literatures with similar structures are mainly obtained by condensation of diethyl phenylethylmalonate and thiourea as raw materials under the catalysis of sodium ethoxide, but due to the generation of a large number of by-products, the yield is relatively low. low, and difficult to produce industrially
Anhui Chemical Industry, volume 33, the synthetic research of paper phenobarbital reported in the 2nd phase, its synthetic method is 52.8g (0.1998mol) phenyl ethyl malonate diethyl ester and 14g ( 0.2333mol) carbamide was at reflux (80°C), and 85.8g, 6.7% (w / w) (0.0845mol) of newly prepared sodium ethylate solution was added dropwise within 4 hours, but due to the first generation of The sodium salt of phenobarbital, and the sodium ethylate used in this paper is all converted into the sodium salt of phenobarbital, and at most only 42% of sodium phenobarbital is generated, and the reaction is catalyzed by sodium ethylate Therefore, the disadvantage of this method is that the product yield is low, the efficiency is low, the by-products need to be extracted with xylene, the energy consumption is high, and the content requirement of sodium ethylate in ethanol is also high, there are many three wastes, and the cost high

Method used

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  • Preparation method of 5-methyl-5-phenylbarbituric acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Step A: Add 313.5 g of sodium methoxide (sodium methoxide content: 31% w / w) methanol solution into the reaction flask, then add 3.5 g of ethyl acetate, heat up to slight reflux for 25 minutes to eliminate free alkali. Then, 108.0 g of urea and 250.3 g of diethyl α-methyl-α-phenylmalonate were added, and the temperature was raised to distill and recover the solvent to an internal temperature of 115°C. The concentrate was decompressed into foam, cooled to below 30°C, added 876g of cold water at 5°C and stirred to dissolve. Then add refined and recovered activated carbon, filter, and the filtrate is acidified with hydrochloric acid until crystallization pH=3.5, filtered, washed with water, and dried to obtain 208.2 g of crude compound (I), with an HPLC content of 99.32%.

[0017] Step B: Add the crude product of compound (I) obtained in step A into the reaction flask, then add 728.7 g of 70% ethanol aqueous solution and activated carbon, heat up and reflux for decolorizati...

Embodiment 2

[0019] Step A: Add 409.7g of sodium methoxide (sodium methoxide content: 29% w / w) methanol solution into the reaction flask, then add 4.5g of ethyl acetate, and heat up to slight reflux for 30 minutes to eliminate free alkali. Then, 108.0 g of urea and 250.3 g of diethyl α-methyl-α-phenylmalonate were added, and the temperature was raised to distill and recover the solvent to an internal temperature of 113°C. The concentrate was decompressed into foam, cooled to below 30°C, added 1001g of cold water at 2°C and stirred to dissolve. Then add refined and recovered activated carbon, filter, and the filtrate is acidified with hydrochloric acid until crystallization pH=4, filtered, washed with water, and dried to obtain 208.6 g of crude compound (I), with an HPLC content of 99.15%.

[0020] Step B: Add the crude product of compound (I) obtained in step A into the reaction flask, then add 834.4 g of 60% ethanol aqueous solution and activated carbon, heat up and reflux for decolorizat...

Embodiment 3

[0021] Example 3: Step A: Add 396g of sodium methoxide (sodium methoxide content is 30% w / w) methanol solution into the reaction flask, then add 4.0g of ethyl acetate, heat up to slight reflux reaction for 20min to eliminate free alkali. Then add 150.0 g of urea, and then add 250.3 g of diethyl α-methyl-α-phenylmalonate, heat up and distill to recover the solvent to an internal temperature of 110°C. The concentrate was decompressed into foam, cooled to below 30°C, and 1126g of cold water at 3°C ​​was added to dissolve it. Then add refined and recovered activated carbon, filter, and the filtrate is acidified by hydrochloric acid to crystallization pH = 4.5, filtered, washed with water, and dried to obtain 210.6 g of crude compound (I), with an HPLC content of 99.29%.

[0022] Step B: Add the crude product of compound (I) obtained in step A into the reaction flask, then add 947.7 g of 50% ethanol aqueous solution and activated carbon, heat up and reflux for decolorization for 0....

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Abstract

The invention provides a preparation method of 5-methyl-5-phenylbarbituric acid. The method comprises the following two steps: A, performing a reaction on diethyl alpha-methyl-alpha-phenylpropanedioate (referred to a compound III) and urea in the presence of a methanol solution of sodium methoxide to prepare sodium 5-methyl-5-phenyl barbiturate (referred to a compound II); and performing acidification on the compound (II) by using hydrochloric acid to obtain a crude product of the compound (I); and B, performing recrystallization on the crude product of the compound (I) obtained in the step Ain an ethanol aqueous solution to obtain a fine product of the compound (I). According to the preparation method provided by the invention, the reaction conditions are easy to control, the product quality is stable, the obtained crude product has a content of 99.0% or more by HPLC, and after primary purification, the purity of the product by the HPLC is >99.8%; and the production costs are low, and the method is more suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of chemical synthesis and relates to a preparation method of 5-methyl-5-phenylbarbituric acid. Background technique [0002] The present invention conducts experimental research with reference to the inventor's own invention patent ZL 2010 1 0211476.1, a preparation method of 5-ethyl-5-phenylbarbituric acid (compound I for short). Finally, a kind of diethyl α-methyl-α-phenylmalonate (compound III for short), in the presence of methanol solution of sodium methoxide, reacts with urea to generate 5-methyl-5-phenyl Sodium barbiturate (referred to as compound II) is acidified with hydrochloric acid to obtain the crude product of compound I, and then recrystallized by ethanol aqueous solution to prepare a new process for preparing 5-methyl-5-phenylbarbituric acid compound I. [0003] The existing synthetic methods reported in related literatures with similar structures are mainly obtained by condensation of diethyl phenyle...

Claims

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Application Information

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IPC IPC(8): C07D239/62
CPCC07D239/62
Inventor 朱连博郑忠辉
Owner SHANDONG XINHUA PHARMA CO LTD
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