Mechanisms of double-bond migration reactions of pentene isomers on different Lewis acids

Abstract

Double-bond migration (DBM) reaction mechanisms of pentene isomers on two samples with different Lewis acid sites (LASs) were investigated by in situ diffraction infrared Fourier transform spectrum (DRIFTS). The conversion of n-pentene to cis-2-pentene on sample Si-Beta proceeded through AB-AD mechanism and the following transformation of cis-2-pentene into trans-2-pentene occurred via AD-AB mechanism, which were different from conversion of n-pentene to cis-2-pentene and trans-2-pentene concurrently by AB-AD mechanism on AlCl3@γ-Al2O3 without hydroxyl. Similarly, the interconversion of 2-methyl-1-butene and 2-methyl-2-butene followed AB-AD mechanism on AlCl3@γ-Al2O3. However, 2-methyl-1-butene was transformed into 2-methyl-2-butene by AB-AD mechanism on Si-Beta, whereas the reversible reaction proceeded by AD-AB mechanism. Furthermore, the occurrence of DBM reaction of 3-methyl-1-butene on Si-Beta and AlCl3@γ-Al2O3 was not observed.