The Study Of Preparation Of Erythromycin Thiocyanate By Reactive Crystallization

Erythromycin Thiocyanate is a kind of medicine used for animals at first. It is usually applied for animal growth promoters. Besides, it can be used to synthesize some half-synthesized erythromycins that are popular in the global market such as clarithromycin, roxithromycin and azithromycin. Erythromycin Thiocyanate are widely used because they improve the solubility of erythromycin in the water and reduce the toxic effects. Recently, the demands of clarithromycin, roxithromycin and azithromycin in the domestic and international markets are increasing. As the raw material, Erythromycin Thiocyanate was in a tension supply and the price was increasing. However, the research on Erythromycin Thiocyanate was scarcely reported. Also, the production process of Erythromycin Thiocyanate is based on producer operation and has some limits on its yield and quality. Focus on this point, this paper did a detailed and systematic research on the reaction crystallization process of Erythromycin Thiocyanate in water and ethyl butyrate and obtain its thermodynamic and kinetic data, so provide the practical guiding significance for the optical crystallization process.During the thermodynamic research, the solubility data of Erythromycin Thiocyanate in water and ethyl butyrate were obtained by means of weight method. The influence of pH on solubility was also studied. The width of crystallization metastable zone was calculated by material balance method and the influence of operation factors on this.The crystallization kinetic data of Erythromycin Thiocyanate at different reaction velocities were measured using intermittent dynamic method. The nucleation kinetic equation was obtained by regressing data using transformation method of moments and least square method.The stabilities of Erythromycin Thiocyanate at different pH were studied by chromatography method. The pH operation region in the crystallization process was determined according to experimental analysis.On the basis of the above related research, the optical Erythromycin Thiocyanate production process was also conducted. Aimed on the yield and the content of A, the influence of initial Erythromycin concentration, contents of NaSCN and glacial acetic acid, NaSCN concentration on crystallization were discussed. The steady yield and high content of A component can be obtained after the optimization. This paper provides certain theoretical bases to thermodynamic and kinetic research of Erythromycin Thiocyanate.