The method of synthesis of barbituric acid from barbituric acid
Raw materials and preparation
To make barbituric acid, you need to prepare barbituric acid, which is the foundation. In addition, various reagents are required, such as suitable alkali, and halogenated hydrocarbons with specific structures. The structure of halogenated hydrocarbons has a great influence on the reaction direction and product purity. When carefully selected, ensure that it meets the reaction requirements. An instrument, such as a reactor, a condenser, a thermometer, etc., should be clean and intact to facilitate a smooth reaction.

Reaction steps
Place barbituric acid carefully in the reactor, slowly inject an appropriate amount of alkali, and the concentration of the alkali needs to be precisely controlled, which is related to the reaction rate and product generation. Stir well to make the barbituric acid fully interact with the alkali solution to form a corresponding salt. During this process, the temperature also needs to be maintained within a certain range, which can be monitored in real time by a thermometer. If the temperature is too high or too low, it may cause reaction deviation.

After the barbiturate is formed, add carefully selected halogenated hydrocarbons dropwise, and the dripping speed should be slow to prevent overreaction. After the dripping is completed, continue to stir to promote the full reaction of the two. The reaction time depends on the actual situation. During this period, close attention should be paid to the reaction phenomena, such as the color change of the solution and the formation of precipitation.

Product separation and purification
The reaction ends, and the product is mixed in the reaction system. First extract with a suitable organic solvent to enrich the barbiturate in the organic phase. The extraction process requires multiple operations to improve the extraction efficiency. Then, the organic phase is distilled to remove the organic solvent to obtain a crude barbiturate.

The crude product still contains impurities and needs to be further purified. The method of recrystallization can be used to choose a suitable solvent, dissolve the crude product, heat it to a suitable degree, so that the impurities remain in the solution or form insoluble matter. Filter while hot, and after the filtrate cools, the barbiturate crystals precipitate. Filter the crystals and dry them at low temperature to obtain a pure barbiturate product. The purity and quality can meet the subsequent needs of use.