Journal of photochemistry and photobiology a-chemistry vol:157 issue:2-3 pages:269-274
The branching fraction of H-abstraction in the elementary reactions of acetaldehyde and propionaldehyde with OH at 290 K was determined directly using a fast-flow reactor coupled to a molecular beam sampling mass spectrometry apparatus. The primary-product H2O yield of the title reactions was quantified relative to that of the isobutane + OH reaction, and found to be 89+/-6 and 100+/-10% for the reactions of acetaldehyde + OH and propionaldehyde + OH, respectively. Furthermore, an upper limit of 3% could be determined for the yield of formic acid in the hypothetical addition/elimination reaction pathway. We conclude that the reaction of OH radicals with aldehydes proceeds predominantly, if not exclusively, via H-abstraction, forming H2O and R-CO. (C) 2003 Elsevier Science B.V. All rights reserved.