AN AB-INITIO STUDY OF THE REACTION OF ATOMIC FLUORINE AND CHLORINE WITH TRIFLUOROACETALDEHYDE

In the present work, ab initio molecular orbital theory has been used to examine the reaction of atomic fluorine and chlorine with trifluoro acetaldehyde CF3C(O)H. Equilibrium geometries and transition state str uctures have been fully optimized at the unrestricted second-order Mol ler-Plesset (UMP2/6-31G()) lever of theory. Activation barriers and h eats of reaction have been estimated using fourth-order Moller-Plesset perturbation theory with spin projection including single, double, tr iple and quadruple excitations (PMP4 (SDTQ)). The predicted activation barrier for the abstraction of hydrogen from trifluoroacetaldehyde, a s from similar compounds, is found to be higher for chlorine than for fluorine atoms. Barriers for hydrogen abstraction are lower for CF3C(O )H than for HFCO, in accord with known trends in substituent effects.