SEPARATION OF CLOSE ISOMERS BY ENCLATHRATION. A. Horne^a, M. R. Caira^a, L. R. Nassimbeni^a, K. Okuda^b and F. Toda^{b a}Department of Chemistry, University of Cape Town, Rondebosch 7700, South Africa ^bDepartment of Applied Chemistry, Faculty of Engineering, Ehime University, Matsuyama 790, Japan

The separation of close isomers by clathrate formation is industrially important because it is simple, efficient and is not energy intensive. The process relies on molecular recognition between host and guest molecules, and typically consists of dissolving an appropriate host compound in a mixture of two or more guests, allowing the formation of a crystalline inclusion compound which is enriched with respect to a particular guest. The inclusion compound is filtered and the enriched guest released by gentle warming, so that the host compound can be recycled. Depending on the selectivity of the process, separation of the targeted guest of >90% is usually achieved in at least three cycles^l-2.

1. D. R. Bond and F. Toda, Acta Crystallogr., Sect. C, l991, 47, 348.

2. I. Goldberg, Z. Stein, K. Tanaka and F. Toda, Chem. Lett., 1987, 1617.