Calculation of kinetic isotope effects in formation of carbon dioxide from a diester of oxalic acid

Abstract

Equations for the calculation of isotope effects (k12/k13 and k16/k18) in the concerted twobond thermolysis of oxalates are presented. The equations are developed for material of low isotopic abundance such that the presence of doubly labelled molecules can be ignored. No assumption is made about the distribution of 18O between the carbonyl and ether functions, other than that the distribution is known. The experimental data required are the ratios CO246/CO244, and CO245/CO244, corrected for the presence of 17O and 14C, in the CO2 obtained from partial decomposition and in the CO2 from total decomposition and the fractional extent of reaction.