Catalytic behaviors of silica-supported chitin-platinum complex for asymmetric hydrogenation of alpha-phenylethanol

Silica-supported chitin-platinum complex (SiO2-CT-Pt) has been prepared and found to be a high stereoselective catalyst for asymmetric hydrogenation o f racemic alpha-phenylethanol to R-(+)-1-cyclohexyl ethanol at 30 degrees C and under an atmospheric hydrogen pressure. The optical selectivity of R-( +)-1-cyclohexyl ethanol amounted to 100% when a fitting condition was selec ted. In this case, the yield and optical selectivity were affected greatly by many factors, such ast content in SiO2-CT-Pt complex, the reaction tempe rature, the solvent, and the amount of the additive of hydrochloric acid, e tc. SiO2-CT-Pt catalyst also has shown high stability. The optical selectiv ity for R-(+)-1-cyclohexyl ethanol was almost keeping at 100% when the cata lyst was reused for many times. Moreover, SiO2-CT-Pt complex is an economic al chiral catalyst. The chitin is an abundant natural biopolymer and the pr ocedure for preparation of the complex is very simple. (C) 2000 Elsevier Sc ience B.V. All rights reserved.