Kinetics of deuterium isotope exchange between 2-methylpropane-2-thiol and propane-2-thiol in aprotic solvents

Abstract

The rate constants for bimolecular deuterium isotope exchange between 2-methylpropane-2-thiol and propane-2-thiol in C₆D₁₂, CCl₄, (CD₃)₂CO, HCON(CH₃)₂, (CD₂)₄O, and (CH₃)₂SO solutions were determined by use of ¹H n.m.r. analysis. The rate constants, k, and activation enthalpy, ΔH^‡, decrease, and entropy, –ΔS^‡, increases, with an increase in the ability of the solvents to form hydrogen bonds with alkanethiols. The rate constant of concerted hydrogen transfer inside the cyclic dimer of alkanethiols with two H-bonds, k₃, increases with increasing dielectric constant of the solvent.