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Preparation method for 1.3-dimethylbarbituric acid

A technology of dimethyl barbituric acid and dimethyl urea, applied in the field 1, can solve the problems of low yield and high cost of raw materials, and achieve the effects of high yield, low cost of raw materials and excellent product quality

Active Publication Date: 2008-06-04
上海三爱思试剂有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This prior art has only about 50% due to the high cost of raw materials and low yield, and the appearance of the product is yellow crystal with a melting point of 119-120°C, which needs to be improved.

Method used

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  • Preparation method for 1.3-dimethylbarbituric acid

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0013] Add 1.1 mol of dimethyl malonate and 1.0 mol of 1,3-dimethylurea to the reactor, then add 900 grams of solvent n-butanol and toluene and 58 grams of sodium ethoxide as catalyst, and heat to 90-110°C with stirring. The reaction was refluxed for 10 hours. After the reaction, the reactants were cooled to precipitate solids. Dissolve the solids in water, add hydrochloric acid to adjust the pH to 1-2, cool to precipitate crystals, filtered to obtain 132 grams of crude product, recrystallized to obtain 119 grams of pure product, melting point 121.4-123.2°C , The yield is 76%, and the content is 99.7%.

Embodiment 2

[0015] Add 1.2 mol of diethyl malonate and 1.1 mol of 1,3-dimethylurea into the reactor, then add 1150 g of solvent n-butanol and toluene, 72 g of sodium ethoxide as catalyst, and heat to 100-120°C under stirring. The reaction was refluxed for 9 hours. After the reaction, the reactants were cooled to precipitate solids. The solids were collected by filtration. The solids were dissolved in water, adjusted to pH 1-2 with hydrochloric acid, cooled to precipitate crystallization, filtered to obtain 144 grams of crude product, and recrystallized to obtain pure product 130 g, melting point 121.3-123.1°C, yield 75%, content 99.6%.

Embodiment 3

[0017] Add 1.3 mol of dimethyl malonate and 1.2 mol of 1,3-dimethylurea into the reactor, then add 1100 grams of solvent n-butanol and toluene, and 70 grams of sodium ethoxide as catalyst, and heat to 100-120°C under stirring. Reflux the reaction for 10 hours. After the reaction, the reactants were cooled to precipitate solids. The solids were collected by filtration. The solids were dissolved in water, and hydrochloric acid was added to neutralize the pH to 1-2. The crystals precipitated after cooling were filtered to obtain a crude product, 157 grams, and recrystallized 141 grams of pure product was obtained, the yield was 75%, the melting point was 121.3-123.1°C, the yield was 75%, and the content was 99.6%.

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Abstract

The invention discloses a method to prepare 1, 3-dimethyl barbituric acid through the reaction of malonic ester and 1, 3-dimethylurea. The method adopts sodium alcoholate as catalyst and lower aliphatic alcohol or the mixture of the lower aliphatic alcohol and phene, toluene or dimethyl benzene as solvent, wherein, the catalyst and the solvent are blended in a reactor to a raised temperature of 60-120 DEG C and done with reflux reaction for 9-10 hours; after the completion of the reaction, the reacted product is cooled to precipitate solid which is then filtered and then dissolved in water; then the pH of the solution is adjusted to 1-2 by adding hydrochloric acid and cooled to precipitate crystal, which is filtered again and crystallized again to obtain the 1, 3-dimethyl barbituric acid. The invention has low-cost raw materials, simple operation and high product yield.

Description

1. Technical Field [0001] The invention relates to a method for preparing 1,3-dimethylbarbituric acid, and more specifically to a method for preparing malonate and 1,3-dimethylurea as raw materials, and sodium alkoxide as a catalyst. Synthetic method of 1,3-dimethylbarbituric acid. 2. Background technology [0002] 1,3-Dimethylbarbituric acid is white or light yellow crystals, soluble in ethanol, with a melting point of 121-123°C. It is an important chemical intermediate and is widely used in the chemical and pharmaceutical industries. According to the literature (Beil 24 IV1875) (E471 EI 270), the conventional preparation method of 1,3-dimethylbarbituric acid is malonic acid, 1,3-dimethylurea is used as a solvent in glacial acetic acid, and acetic anhydride In order to produce 1,3-dimethylbarbituric acid by reaction of dehydrating agent at 60~90℃, the solvent and excess acetic anhydride are removed by distillation, and ethanol is added to precipitate the crude product. The crude...

Claims

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Application Information

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IPC IPC(8): C07D239/62
Inventor 柯德宏贾瑜茅永娣
Owner 上海三爱思试剂有限公司
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