Investigation Of Ethyl Vanillin Crystallization Process

Ethyl vanillin (EVA) is one of the most valuable synthetic perfumes nowadays, which can be wildly applied in the manufacture of food and cosmetics. EVA is gradually used as an alternative to vanillin in recent years and it possesses a flavour and odour approximately three times as intense as vanillin, which leads to a lower dosage and cost. But the EVA does not exist naturally, and it has been prepared synthetically by various methods. At present, most of researches about the EVA are still mainly focused on the synthesis and optimization technology, but very few people have attempted to establish detailed purification methods to obtain products with high purity and yield. For these, the cooling crystallization process of EVA was studied systematically in this paper.(1) The EVA products were crystallized from six different solvents, and the samples were characterized and tested with the help of microscope observtion, XRPD, DSC, FT-IR, HPLC techniques. By the analysis, we may come to the conclusion that the EVA crystal form is unique and the effect of solvent type on crystal habit is significant. Compared to others the n-butanol solvent turned out to be the best choice for the subsequent crystallization process to obtain high-quality product. Besides that, with the crystallographic data from CCDC, the MS simulation software was used to predict the growth habit of EVA. The calculated results showed that the Growth morphology model get a preferable and relatively satisfactory result.(2) The solubility of EVA in six single solvents and two binary solvents were determined experimentally by a laser monitoring observation technique. All the measured data in pure solvents were regressed by different models, with the NRTL model showing the best agreement. Moreover, the mixing thermodynamic properties of solution system were predicted on the basis of NRTL model. Similarly, the solubility data in binary solvent mixtures were also correlated by the NRTL model. Finally, the metastable zone width of EVA in n-butanol solvent was measured by laser method as well, and the effects of agitation speed, cooling rate and addition of seeds or not were analyzed experimentally.(3) On the basis of crystallization thermodynamic and crystal morphology research, the cooling crystallation procedure of EVA from n-butanol was investigated for the purpose of getting excellent products. The influence of many operation conditions on the CSD, crystal habit, purity and yield were investigated, and the optimal process parameters was determined.