The Thermal Decomposition of Haloacetic Acids: a Laser Pyrolysis and Semiempirical Study.

Abstract

Infrared laser-powered homogeneous pyrolysis, coupled with Fourier-transform infrared measurement of product distributions, has demonstrated that four different unimolecular mechanisms are significant in the initiation of gas-phase thermal decomposition of CH₃COOH (1), CF₃COOH (2), CH₂ClCOOH (3), CHCl₂COOH (4), CCl₃COOH (5), CH₂BrCOOH (6), and CH₂ICOOH (7): decarboxylation and dehydration for (1); H-X elimination for (2)-(6); and C-X bond homolysis for (6) and (7). These conclusions are supported by the semiempirical calculation of activation energies for the possible pathways.