Transition structures for one step nonconcerted oxygen insertion mechanism of oxidation of alkanes with trifluoroperoxyacetic acid

High level calculations (UB3LYP/6-31G∗) on the oxygen insertion by trifluoroperoxyacetic acid (TFPA) into methane and isobutane C–H bonds strongly supports the viability of a one step nonconcerted mechanism. That is, the O–H bond forms first and the C–O bond formation commences afterwards, but only one first order saddle point, exhibiting high diradical character and strong polarization, is present on the energy profile of the minimum energy path. No minima corresponding to intermediates were located. IRC analysis suggests that the transition structure can collapse directly to products with retention of configuration at the alkane carbon center.