Catalysis by hydrogen chloride in the gas‐phase elimination kinetics of 2‐phenyl‐2‐propanol and 3‐methyl‐1‐buten‐3‐ol

Abstract

AbstractA homogeneous, molecular, gas‐phase elimination kinetics of 2‐phenyl‐2‐propanol and 3‐methyl‐1‐ buten‐3‐ol catalyzed by hydrogen chloride in the temperature range 325–386 °C and pressure range 34–149 torr are described. The rate coefficients are given by the following Arrhenius equations: for 2‐phenyl‐2‐propanol log k1 (s−1) = (11.01 ± 0.31) − (109.5 ± 2.8) kJ mol−1 (2.303 RT)−1 and for 3‐methyl‐1‐buten‐3‐ol log k1 (s−1) = (11.50 ± 0.18) − (116.5 ± 1.4) kJ mol−1 (2.303 RT)−1. Electron delocalization of the CH2CH and C6H5 appears to be an important effect in the rate enhancement of acid catalyzed tertiary alcohols in the gas phase. A concerted six‐member cyclic transition state type of mechanism appears to be, as described before, a rational interpretation for the dehydration process of these substrates. Copyright © 2007 John Wiley & Sons, Ltd.