|
Résumé :
|
A kinetic study involving stoichiometry, order of reaction, rate constants (k), and rate laws has been performed on carboxylation of toluene by CO2 generating p-toluic acid by two routes: (a) Friedel—Crafts reaction, C6H5―CH3 + CO2 + Al2Cl6 → CH3―C6H4―COOAl2Cl5 + HCl and (b) Friedel―Crafts reaction with incubation method involving two steps, CO2+ + Al2Cl6 → CO2:Al2Cl6 and CO2:Al2Cl6 + C6H5―CH3→ CH3―C6H4―COOAl2Cl5 + HCl. The adduct OCO:Al2Cl6 was estimated by monitoring the peak at 1662 cm―1 in the FT1R spectra. The k values for the Friedel-Crafts reaction was found to be 2.28 × 10―9 mol―2 h―1, which is much lower than that for the reactions involved in the incubation method, viz, 5.4 × 10―5 and 1.9 X 10―3 mol―1 h―1, respectively. ΔE, ΔG, ΔS, ΔH, and the Arrhenius constant (A) have been calculated for the above reactions. Comparison shows that the incubation method is faster than the Friedel-Crafts reaction. However, both the reactions follow first order kinetics with respect to each of the reactants.
|
