Author/Authors :
Zakarianezhad، M نويسنده Department of Chemistry, Payam Noor University, Tehran, I.R of Iran , , Habibi-Khorassani، S. M نويسنده Department of Chemistry, The University of Sistan and Baluchestan, P. O. Box 98135-674, Zahedan, Iran , , Maghsoodlou، M. T نويسنده Department of Chemistry, The University of Sistan and Baluchestan, P. O. Box 98135-674, Zahedan, Iran , , Makiabadi، B نويسنده Department of Chemical Engineering, Sirjan University of Technology, Sirjan, Iran , , Ghasempour، H نويسنده Department of Chemistry, Bardsir Branch, Islamic Azad University, Bardsir, Iran ,
Abstract :
Kinetic studies were made of the reactions between triphenylphosphine 1, dialkyl acetylenedicarboxylates 2 in the
presence of NH-acid, such as maleimid (as a protic/nucleophilic reagent) 3. To determine the kinetic parameters of
the reactions, they were monitored by UV spectrophotometery. The second order fits were automatically drawn
and the values of the second order rate constant (k2) were automatically calculated using standard equations within
the program. All reactions were repeated at different temperature range, the dependence of the second order rate
constant (ln k2) and (ln k2/T) on reciprocal temperature was in a good agreement with Arrhenius and Eyring
equations. This provided the relevant plots to calculate the activation parameters (Ea, ?H?, ?S? and ?G?) of all
reactions. Furthermore, useful information was obtained from studies of the effect of solvent, structure of reactants
(dialkyl acetylenedicarboxylates) and also concentration of reactants on the reaction rates. The proposed
mechanism was confirmed according to the obtained results and steady state approximation, and the first and third
steps (k2, k3) of all reactions were recognized as rate determining and fast steps, respectively on the basis of
experimental data.
