Phenylglycinol, also called 2-Amino-2-phenylethanol, is an important chiral compound and can be used for the synthesis of many pharmaceutical intermediates. For example, R-(-)-phenylglycinol can be used as an important precursor of HIV-1 protease inhibitor. S-(+)-phenylglycinol can be used to synthesize pipecolic acid, which is a precursor to numerous compounds such as synthetic peptides, local anesthetics or potential enzyme inhibitors. As high-purity pure enantiomer is required in the synthesis of pharmaceuticals, various separation methods to obtain R or S-Phenylglycinol have been proposed in the literature, including extractant impregnated resins, liquid-liquid extraction, chiral-modified zeolite HY.Stripping crystallization (SC), also called distillative freezing (DF), has been developed recently in our laboratory to separate the mixtures with close boiling temperatures [1-2]. SC is introduced in this work for purification of phenylglycinol enantiomers. In principle, SC is operated at a series of the three-phase equilibrium conditions, in which the liquid mixture is simultaneously vaporized and crystallized. Thus, SC combines distillation and crystallization to produce pure crystals. A thermodynamic model is developed to simulate the three-phase equilibrium during the SC operation and to direct the batch SC experiments. The experiments confirm that SC can be efficiently employed to purify R-phenylglycinol from phenylglycinol enantiomers. Among various operating pressures adopted during SC, the final purity of the product increases with decreasing operating pressure while the recovery ratio decreases with decreasing operating pressure.1. Shiau LD, Wen CC, Lin BS. Application of distillative freezing in the separation of o-xylene and p-xylene. AIChE J.2006; 52(5): 1962-1967.2. Shiau LD, Wen CC, Lin BS. Separation of p-xylene from the multicomponent xylene system by stripping crystallization. AIChE J. 2008; 54(1): 337-342.

Chiral purification of phenylglycinol enantiomers by stripping crystallization

245th National Meeting (2013)

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