Study On The Synthesis Of Florfenicol

Florfenicol,the third generation of chloramphenicol antibiotics,is a chemical synthesis broad-spectrum antibiotic for animals.Florfenicol is mainly used for aquaculture,and has many advantages,such as wide spectrum,high efficiency,low toxicity,good absorption,widely distributed in the body and low toxicities.Thus the synthesis study of Florfenicol has important industrial application values.This thesis reviewed the synthesis of florfenicol,and designed a new synthetic process which has also been improved and optimized.In the first step,D-ethyl ester,a starting material,was reducted by potassium borohydride,and then cyclized by dichloroacetonitrile(yield 86.3%and purity 96.8%).In the second step,the cyclization product was fluorated by ishikara reagent to form fluorine thiamphenicol oxazole.The amount of hexafluoropropylene is reduced to 70%of reported amount in the literature by lowering the reaction temperature,while the yield(91.9%)and the quality(liquid purity 98.3%)were not change.In the third step,fluorine thiamphenicol oxazole was hydrolyzed to form florfenicol.The yield and the quality were improved to 92.3%and 99.4%(liquid content)by changing the solvent and its concentration(reacting in high concentration and crystallizing in low concentration).After our improvements,the synthesis process of florfenicol is more suitable for industrial production with a high overall yield 82.1%(yield 70%of the literature),stable quality,short steps,easy operations and low cost?...