Measurment Of The Basal Crystallization Data And A Study On Dilution Crystallization Technology Of Heliotropine

Heliotropine is one of the important perfumes and can be applied in many fields. In allusion to the quality problems of the heliotropine product made in China, such as poor crystal morphology, asymmetry CSD and aggrelation, the crystallization process and new technology for heliotropine were systematically investigated and analyzed. The crystal structure of heliotropine was firstly tested with the single crystal X-ray diffraction and powder X-ray diffraction methods and the structure parameters were gained. Then the morphologies of heliotropine under the vacuum condition were simulated by Cerius2 software with BFDH and AE models respectively. After comparing with the experimental results, it was found that the morphology simulated by AE model quite resemble that obtained in the experiments. The solubilities of heliotropine in different pure solvents and in the mixture solvents of water together with ethanol and together with isopropyl ethanol with different ratio were measured by dynamic method. It was shown that the solubility in pure solvent was preferably fitted by Apelblat model, while the solubilities in the mixture solvents were well fitted by CNIBS/Redlich-Kister model. The metastable zone widthes of the supersaturation solution of heliotropine in the mixture solvents of ethanol and water with different volume ratio were also measured by laser method. The induction period of the crystallization process of heliotropine was also studied, by which the surface tension between crystal and solution was calculated. The cooling crystallization kinetics of heliotropine in pure ethanol and in the mixture solvent of ethanol and water with different volume ratio were measured experimentally by batch dynamic method. The effects of temperature, the supersaturation, the suspension density, the agitation speed on the nucleation rate and the crystal growth rate were investigated. A size-independent model was chosen to deal with the experimental data. by means of the moment transform method, the model equations of the nucleation rates and the crystal growth rates in the crystallization process of heliotropine were obtained through the least square multivariate linear regression. Aimed at the quality demand of the heliotropine crystal product, the effects of operational parameters such as crystallization method, the size and the quantity of seeds, the seeding temperature, the cooling rate, the agitation speed, the adding rate of diluent, the adding temperature of diluent and the cultivation crystal time on the CSD, yield and morphology were experimentally investigated systematically and the optimum operational conditions for the crystallization of heliotropine were finally obtained.