【作者】 高海见；

【导师】 尹秋响；

【作者基本信息】 天津大学 ， 化学工程， 2005， 硕士

【摘要】 5’-脲苷酸二钠属于核苷酸类化合物,是常用的食品添加剂。国际市场上, 5’-脲苷酸二钠产品主要被日本、韩国等国所垄断,国内产品在纯度、晶体粒度及晶习等方面与国外同类产品存在较大的差距,因而在国际市场竞争中处于不利的地位。针对国内5’-脲苷酸二钠生产中存在的结晶技术落后、产品质量差的问题,本文对5’-脲苷酸二钠溶析结晶过程进行了系统研究。晶体结构的研究对了解晶体生长过程和机理具有重要的指导意义。本文采用X-射线粉末衍射和X-射线单晶衍射的方法,收集了5’-脲苷酸二钠晶体衍射数据和单晶CIF数据,利用Cerius2软件计算出了5’-脲苷酸二钠晶体的分子空间结构与晶胞参数,并应用BFDH与AE模型对5’-脲苷酸二钠的晶习进行了预测。采用激光法测定了不同温度下5’-脲苷酸二钠盐在不同配比溶剂中的溶解度、介稳区宽度与成核诱导期。利用差式扫描量热法(DSC)测定了5’-脲苷酸二钠的熔点和熔化焓。利用间歇动态法,对5’-脲苷酸二钠溶析结晶动力学进行了研究,并采用矩量变换法处理动力学数据,回归出了生长速率和成核速率方程,并分析了过饱和度、搅拌速率等各种操作条件对成核速率和生长速率的影响。在结晶热力学和动力学的研究基础上,对5’-脲苷酸二钠的结晶工艺进行了系统研究。实验结果表明,要从含杂质较多的5’-脲苷酸二钠原料液中制取高质量的结晶产品,必须首先通过初步结晶提取较高纯度的5’-脲苷酸二钠原料,然后再进行重结晶进一步精制。初步结晶过程的最佳工艺条件为:结晶温度为10℃,搅拌速率为400rpm,加入乙醇量为原料液体积的0.65。获得的5’-脲苷酸二钠原料纯度≥90%的,收率可达到85%以上; 重结晶精制过程的最佳工艺条件为:结晶温度10℃,搅拌速率500rpm,溶析剂流加速率0.4ml/min,加入3%的晶种。制备出了纯度高、粒度分布均匀、晶形明显改善的5’-脲苷酸二钠产品。更多还原

【Abstract】 Uridine is a kind of nucleotide compound, its disodiun 5’-monophosphate salt is of special value for food enrichment. Industrial crystallization is the most important process of producing disodium uridine-5’-monophosphate （5’-UMP Na2）. The advanced technology for producing 5’-UMP Na2 is monopolized by Japan and South Korea in the world. Up to now, there are some differences between the home-made and the overseas 5’-UMP Na2 products in terms of the purity, the crystal size distribution and habit, etc. Therefore, the domestic products are incapable in competing with the overseas products in the international market. In allusion to this situatuin, the dilution crystallization process of 5’-UMP Na2 was systematically investigated. The sduty of the crystal structure is very important for exploring the crystal growing mechanism. The diffraction pattern and the single crystal CIF data for 5’-UMP Na2 were collected by powder and single crystal X-ray diffraction technique. The molecular structure and the crystal cell parameters were calculated by the Cerius2 software, and then the crystal habit of 5’-UMP Na2 were predicted by using the BFDH and AE models. The solubilities, the metastable zone width and the nucleation induction period of 5’-UMP Na2 in the mixure solvents with different volume ratio at different temperature were measured by the laser method. The melting point and the phase enthalpy of 5’-UMP Na2 were also measured by Differential Scanning Calorimetry（DSC）. The crystallization kineties of 5’-UMP Na2 were studied by the batch dynamic method in this paper. The models for the nucleation rate and the crystal growth rate of 5’-UMP Na₂ were obtained by regressing the kinetic experimental data after translating them in moment forms. The effects of the operational parameters such as the supersaturation and the stir speed on the nucleation rate and the crystal growth rate were analyzed by these models. Based on the studies of the crystallization thermodynamics and kinetics, the crystallization technology of 5’-UMP Na2 was systematically investigated. The experimental results show that in order to get high quality crystal products from the feed liquor containing many impurities, the 5’-UMP Na2 material with high purity should be firstly obtained through a preparatory crystallization process and then be refined through a recrystallization process. The optimal operational condition for the preparatory crystallization process is as follow: a temperature at 10℃ , a stir speed at 400rpm and a ratio of ethanol to the feed liquor at 0.65. Under this condition, a 5’-UMP Na2 material with a purity of higher than 90% can be obtained with a yield of higher than 85%. The optimal operational condition for the recrystallization process is as follow: a temperature at 10℃ , a stir speed at 500rpm, an addition rate of diluent at 0.4ml/min and a seed quantity at 3%. Finally, a 5’-UMP Na2 product with a high purity, an identical CSD and an improved crystal habit was obtained.更多还原