Gas-phase hydrogen chloride-catalysed decomposition of some cyclic alcohols

Abstract

The gas-phase thermal decomposition of cyclopentanol, cyclohexanol, and cycloheptanol catalysed by hydrogen chloride in a seasoned Pyrex reaction vessel has been studied in a static system between 693 and 773 K. The reactions are homogeneous. The rate constants (k₂) are defined respectively by the Arrhenius equations (i)–(iii)k₂= 10^{13.36 ± 0.12} exp –(36 143 ± 388)/RT cm³ s^–1 mol^–1(i)k₂= 10^{13.41 ± 0.16} exp –(38 927 ± 529)RT cm³ s^–1 mol^–1(ii)k₂= 10^{12.31 ± 0.18} exp –(32 254 ± 613)/RT cm³ s^–1 mol^–1(iii) where R= 1.987 cal mol^–1 K^–1. The activation energies show a decrease with increasing ring-strain energy changes. The significance of this is discussed.