(73h) Enantioseparation of Phenylethanol By Stripping Crystallization

Stripping crystallization (SC) is a new separation technique which combines distillation and crystallization. Basically, SC is operated at a triple-point condition, in which the liquid is simultaneously vaporized and crystallized due to the three-phase equilibrium. In essence, the process is continued until the liquid phase is completely eliminated and only the pure solid crystals remain in the feed. Thus, crystal washing is not required since only pure solid crystals remain in the feed and no impurities are adhered on the crystal surfaces at the end of SC. In the previous research, SC has been successfully applied to separate p-xylene from the mixed xylenes by Shiau et al. (2005, 2008).

Phenylethanol is an important chiral compound with a number of potential applications. These alcohols are used as building blocks for the synthesis of bioactive compounds such as pharmaceuticals, agrochemicals, and natural products. S-(+)- phenylethanol can be used to treatment of E. coli and other synthetic drugs precursors. A thermodynamic model is developed to simulate the three-phase equilibrium conditions during the SC operation. The experiments show that seeding with magnetic stirring can be efficiently employed to purify S-phenylethanol from phenylethanol enantiomers. The experimental results, including the final enantiomeric purity and recovery ratio of S- phenylethanol, are consistent with the simulation results predicted by the model.

1.  Shiau, L. D., Wen, C. C. and Lin, B. S. Separation and purification of p-xylene from the mixture of m-xylene and p-xylene by distillative freezing, Ind. Eng. Chem. Res, 44(7), 2258-     2265, 2005.

2.  Shiau, L. D., Wen, C. C. and Lin, B. S. Separation of p-xylene from the multicomponent xylene system by stripping crystallization, AIChE Journal, 54(1), 337-342, 2008.