Gas chromatographic determination of activation energy of Schiff's base formation reaction

Abstract

Reaction gas chromatographic technique was employed for the determioation of activation energy of the Shiff's base formation reaction. Benzaldehyde, cyclohexanone or 2-heptanone, which was injected into a gas chromatograph reacted with the amine present in a large excess in the reaction column which also contained the liquid partitioner i.e., QF-1, so that it was possible to treat the reaction as psuedo-first one. The rate constant of the reaction was determined graphically according to the following equation; ln(S_I/S_R) = kt_s ln(S_I/S_R⁰), where S_I and S_R are the peak areas of internal standard and the unreacted aldehyde or ketones, respectively and t_s is the residence time of these reactants in the stationary phase which may be approximated to the corrected retention time.
The rate constant (k) was obtained from a plot of ln(S_I/S_R) vs. t_s and the activation energy was obtained from the slope of the Arrhenius plot of k's at various column temperatures.