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Analysis of Synthetic Technology of 2-Aminothiazole

2019-04-12 来源:亚科官网
 
2-Aminothiazole is a white or light yellow crystal, slightly soluble in water, ethanol, ether, melting point 90 °C, and decomposed upon distillation. It is an important chemical raw material, and is a synthetic intermediate for medicines, dyes, water purifying agents, etc. It is widely used in the synthesis of the third and fourth generations of cephalosporin.
Synthesis of 2-aminothiazole
1. Vinyl acetate and sulphuric acid are used as raw materials
The reaction formula of 2-aminothiazole was synthesized from vinyl acetate and sulfur veins as follows:
The procedure was as follows: In a three-necked flask equipped with a mechanical stirrer, a thermometer and a reflux condenser, thioindole and AcOCH=CH2 (equivalent) were added, and 10% HCI was added with stirring to bring the CI- to saturation at 30 °C. The temperature was controlled at 70 to 80 °C and stirred for 2 h; then neutralized with 40% NaHH until pH 9 to give 95% 2-aminothiazole. The product can be recrystallized and purified with ethanol.
The reaction is carried out in an acidic medium, and SO2CI2 can also be used as a solvent. For example, in 1 equivalent of sulfur veins and 1 equivalent of AcOCH=CH2 solution, SO2CI2 is added, and the control temperature is about 80 °C to obtain 8% of 2-aminothiazole.
The yield of 2-aminothiazole is high, but the raw material is expensive, and the product contains many by-products and impurities, which is difficult to remove.
2, dihaloethyl ether and thioindole as raw materials
The reaction of diaminoethyl ether with sulfur veins to produce 2-aminothiazole is as follows:
The operation steps are as follows: 37.5 mL of water and 11.4 g of sulfur vein are added to a three-necked flask equipped with mechanical stirring, a thermometer and a reflux condenser, and the mixture is heated to dissolve (45-50 °C), and 20.5 g of CH2ClCHOMe is added for reflux for 3.5 h. After completion, 12 mL of 40% NaOH (control temperature 30 to 45 °C) was dropwise added over 6 hours. The pH was made 8. It was then extracted with Et2O and distilled to give 8.2 g of 2-aminothiazole, b15 115-118 C.mP.90C.
The dihaloethyl ether can be replaced by dichloroethyl ether (methyl ether), singeyl ether (methyl ether) or the like. The raw materials are expensive, unstable, easy to decompose, and the reaction by-products are difficult to remove, and the reaction device needs to be well sealed.
Related links: 2-aminothiazole
Edited by Suzhou Yacoo Science Co., Ltd.