The reaction of acrolein with acetylperoxyl radicals in the gas-phase

A rate constant for the epoxidation of acrolein by acetylperoxyl radicals has been determined to be k(4) = (1.3 +/- 0.9) x 10(4) dm(3)mol(-1)s(-1) at 383 K, which is anomalously fast in comparison with the epoxidation of alkenes. Abstraction of the acyl hydrogen atom from acrolein by acetylperoxyl radicals at 393 K was found to be at least 60 times slower than from acetaldehyde and at least three orders of magnitude slower than abstraction of the acyl hydrogen atom of the epoxide of acrolein. The fast rate for epoxidation of acrolein and the slow rate for hydrogen abstraction provide an explanation for the anomalously slow rate for the autoxidation of acrolein and suggests that acrolein formed during the autoxidation of alkene will react further to give its epoxide, and not exclusively by abstraction of the acyl hydrogen atom as was previously accepted. (C) 1999 John Wiley & Sons. Inc.