【作者】 王明；

【导师】 尹秋响；

【作者基本信息】 天津大学 ， 化学工程， 2007， 硕士

【摘要】 甘氨酸是一种结构最简单的氨基酸,应用领域十分广泛。迄今发现甘氨酸晶体有3种晶型:α、β和γ型。我国是甘氨酸的生产大国,但由于结晶技术的落后,不能按要求控制产品的晶型,生产的甘氨酸都是亚稳态的α型产品,产品在储运过程中由于晶型转变易结块,使用非常不便。本文针对我国甘氨酸生产中存在的问题,就常见的α和γ晶型甘氨酸的结晶条件及其转变机理进行了系统的研究。通过在不同的溶液环境下得到的α和γ晶型甘氨酸的单晶,采用X-射线单晶衍射仪测定了其晶体结构,并对晶体中分子堆积情况进行了分析。对α和γ晶型单晶进行了X-射线粉末衍射测定,确定了通过粉末XRD谱图分析甘氨酸混晶中α和γ晶型含量的方法。采用激光动态法考察了α型和γ型甘氨酸在纯水,以及含有一定量的NaOH、NaCl的水溶液中的溶解度。采用Van’t-Hoff方程和Grant方程对甘氨酸在纯水中的溶解度数据进行了关联,两种方程关联的效果均让人满意。对甘氨酸的晶型转变进行了热力学分析。采用DSC法测定了α和γ型甘氨酸晶型转变和熔化过程中的热力学性质。对不同晶型甘氨酸的结晶过程进行了实验探讨,分析了不同晶型甘氨酸的结晶机理,同时研究了影响甘氨酸晶型转变的因素,并结合甘氨酸重结晶和晶型转变对甘氨酸结块机理进行了分析。通过对甘氨酸多晶型结晶和晶型转变的研究,确定了特定晶型甘氨酸的结晶工艺和晶型转变过程的影响因素,为实现甘氨酸晶型的控制和避免产品储运过程中的晶型转变提供了依据。更多还原

【Abstract】 Glycine is the simplest amino acid and can be applied in many fields. So far there are three known polymorphs of glycine,namely,formα,βandγ. China is one of the main manufacture countries in the world. However, as the crystallization technology is undeveloped in China, the polymorph of glycine can’t be controlled in the production process. Glycine made in China is all of theα-form which is metastable and can easily transform into theγ-form during storage. The polymorphic tranaformation can causes caking. The discommodiousness caused by caking in using process is unpleasant. In allusion to the problems mentioned above, the crystallization conditions ofα- andγ-form and the polymorphic transformation mechanism were investigated systematically.The single crystals ofα- andγ-glycine were crystallized in different solution environments. The crystal structures were tested through the single crystal X-ray diffraction (XRD) and powder X-ray diffraction. The packings of molecules in the single crystals ofα- andγ-glycine were analyzed. The analytical method of polymorphic mixture ofα- andγ-glycine was certained by the powder XRD pattern.The solubility ofα- andγ-glycine in pure water and the NaCl and NaOH aqueous solutions were measured experimentally by the laser dynamic method. The experimental data were correlated with Van’t-Hoff equation and Grant equation. It was found that Van’t-Hoff equation and Grant equation could correlate the solubility data very well. Polymorphic transformation of glycine was analyzed thermodynamically. The thermodynamic properities of polymorphic transformation and fusion process ofα- andγ-glycine was tested by Differential Scanning Calorimetry (DSC).The crystallization processes of different polymorphs of glycine were studied experimentally. Crystallization mechanisms of different forms of glycine were ananlyzed. The effects of several parameters on the polymorphic transformation were investigated experimentally and theoretically. Through systemic study of the polymorphic crystallization and transformation, the operational conditions of the crystallization of the appointed form and the effect factors of polymorphic transformation were obtained. It supplied the evidences to realize the control of the polymorph of glycine and avoid polymorphic transformation and caking during storage.更多还原