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The kinetics of the acylation of (R,S)-1-phenylethanol was investigated using lipase as a catalyst. The main parameters were temperature, reaction atmosphere, different acyl donors, and different amounts of acyl donor as well as the presence of some additives in the reaction mixture. The initial reaction rate increased with increasing temperature and with a decreasing amount of an acyl donor. The activated esters, such as isopropenyl-and vinyl acetate, exhibited very high acylation rates for R-1-phenylethanol, whereas low rates were obtained with ethyl acetate and 2-methoxyethyl acetate. The addition of water and acetophenone decreased the acylation rate. A kinetic model was developed based on a sequential step mechanism, in which enzyme was reacting in the first step with an acyl donor followed by the reaction of a modified enzyme complex with the reactant, R-1-phenylethanol. Comparison with experimental data obtained at different temperatures allowed simplification of this model, leading to a kinetic equation with just one apparent parameter. The influence of the amount of acyl donor, ethyl acetate, could be quantitatively described by taking into account the competitive inhibition of the ethanol produced. The rate constants and apparent activation energy for experiments performed under different temperatures and the amounts of acylation agent were determined. The apparent activation energy was 24.5 kJ/mol. C

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The basic N-functionalized vapor-grown carbon nanofibers (N-VGCF) were synthesized by post-treating oxidized VGCFs in gaseous NH3 at high temperature (ammonolysis) prior to Pd addition by sol immobilization. The catalysts were characterized by nitrogen adsorption, hydrogen temperature programmed desorption, adsorption microcalorimetry and by SEM and TEM. Catalytic activity was evaluated in a model reaction, synthesis of (R)-1-phenylethyl acetate starting from hydrogenation of acetophenone to racemic 1-phenylethanol over Pd supported on N-VGCFs, at 70 °C under atmospheric hydrogen pressure in toluene, followed by acylation over an immobilized lipase in the same reaction pot. The main parameters investigated in this work were the role of the basic N-VGCF supports as well as the reduction procedure of the supported Pd catalysts (Pd-N-VGCF). The results revealed that the catalytic activity of the Pd-N-VGCF catalysts was highly dependent on the reduction procedure. The highest desired product yield, 35%, was obtained over a Pd-N-VGCF catalyst when the support was treated at 400 °C with gaseous ammonia prior to Pd addition.

BACKGROUND: A systematic investigation of mutual interference between a hydrogenation catalyst, Pd/Al 2 O 3 , and an immobilized lipase in a one-pot synthesis of R-1-phenyl ethyl acetate at 70• C has been undertaken. This paper reports the kinetic modeling of lipase-mediated chemo-bio cascade synthesis of R-1-phenyl ethyl acetate starting from acetophenone.

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