Rate constant and products for the reaction of Cl atom with n ‐butyraldehyde

The photooxidations of n ‐butyraldehyde initiated by Cl atom were carried out at room temperature (298 ± 2K) and 1 atm pressure. The rate coefficient for the reactions of Cl atom with n ‐butyraldehyde was determined as k = (2.04 ± 0.36) × 10 −10 cm 3 molecule −1 s −1 by using relative rate techniques. The photooxidation products of n ‐butyraldehyde reaction with Cl atom were also studied by using both gas chromatography‐mass spectrometry (GC‐MS) and gas chromatography techniques. C 2 H 5 CHO, CH 3 CHO, CO and CO 2 were the major products observed. In the absence of NO, the observed yields of C 2 H 5 CHO, CH 3 CHO, and CO were 60%, 3%, and 9%, respectively. However, when NO was introduced into the reaction chamber and the initial ratios of [NO] 0 /[ n ‐butyraldehyde] 0 were between 1 and 8, the yield of C 2 H 5 CHO decreased to 33%, whereas that of CH 3 CHO and CO rose up to 21% and 25%, respectively. On the basis of mechanism data deduced in this study and the fraction molar yields, the approximate branching ratios for Cl atom attack at C(O)H, α‐, β‐, and γ‐positions in n ‐butyraldehyde could be derived as ⩾42%, <25%, 21%, and ⩽12%, respectively. © 2007 Wiley Periodicals, Inc. 39: 168–174, 2007