The influence of mineral catalysts on racemization of secondary alcohols under pyrolytic temperatures: II part

Pyrolysis of S-1-phenylethanol (PE) with and without catalysts at different temperatures (80-600 degrees C) has been carried out. In the presence of catalysts the partial racemization (<= 25%) and formation of products like styrene, acetophenone and chiral benzylic ethers formation have been detected. Without a catalyst almost no racemization was observed and products formation was not appreciable. The kinetics of racemization has been calculated and the effect of different kind of catalysts has been studied. Pyrolysis of (S)-1-phenylpropanol (PPEs) and (S)-1-phenyl-2,2,2-trifluoroethanol (FEs) have also been carried out at 500 degrees C on zirconium dioxide. The behaviors of catalysts during pyrolysis experiments are studied using SEM technique. A Principal Components Analysis (PCA) model was created using the results obtained with all catalysts at different temperatures and with the main products, i.e., acetophenone, dibenzylic ethers and styrene to discriminate the catalysts on the basis of their effects. Chemical properties of catalysts that are responsible of different effects are deduced. (C) 2011 Elsevier B.V. All rights reserved.