Abstract
Kinetic studies were made of the reactions between triphenylphosphine, dialkyl acetylenedicarboxylates in the presence of SH-acids, such as 2-thiazoline-2-thiol or 2-mercaptobenzoxazole. To determine the kinetic parameters of the reactions, they were monitored by UV spectrophotometery. The second order fits were drawn by the software associated with a Cary UV spectrophotometer model Bio-300 at appropriate wavelength. The values of the second order rate constant (k2) were calculated using standard equations within the program. Within the temperature range studied, the dependence of the second order rate constant (ln k2) on reciprocal temperature was in agreement with the Arrhenius equation, enabling calculation of the activation energies of all reactions. Furthermore, useful information was obtained from studies of the effect of solvent, structure of reactants (different alkyl groups within the dialkyl acetylenedicarboxylates and SH-acids) and also concentration of reactants on the rate of reactions.