RU-action of OH radical with mono-, di-, and trichloroacetaldehyde: An ab initio study

The hydrogen abstraction reactions between chlorine-substituted acetaldehyd es and OH radicals have been investigated by using ab initio molecular orbi tal theory. Equilibrium geometries and transition-state structures have bee n optimized at the (U)MP2/6-311G(d,p) level. Activation barriers and heats of reaction for different reaction channels have been estimated from the si ngle-point calculations at the (U)MP2/6-311G(2df,2p) level. Three, two, and one hydrogen abstraction channel have been found for the mono-, di-, and t richloroacetaldehyde, respectively. At a higher temperature region, hydroge n abstraction from the formyl group is found to be the major reaction chann el for all the three chloroacetaldehydes. The effect of halogen substitutio n on reactivity toward hydrogen abstraction has been discussed. (C) 2001 Jo hn Wiley & Sons, Inc.