Zeolite screening for the racemization of 1-phenylethanol

To select a suitable system for the racemization of 1-phenylethanol, a commercially relevant chiral alcohol, four acid zeolites and five solvents were screened. Results show that the zeolite/solvent combination influences not only the reaction rate but also the product yield because of their influence on side reactions. As a general rule we can say that the higher the racemization rate, the lower the product yield. The choice of solvent is also important for avoiding catalyst deactivation over time, especially when recycling of the catalyst is envisaged. Kinetic modeling of the results was performed in order to allow a better comparison of the different reaction systems and a more complete analysis of the phenomena underlying their behavior. Of the 20 combinations tested, zeolite H-Beta Si:Al = 75 in ethyl acetate and zeolite H-Beta Si:Al = 12.5 in isooctane, water and vinyl acetate showed the most promising results. (C) 2007 Elsevier B.V. All rights reserved.