Fourier transform infrared study of the kinetics and mechanism for the reaction of hydroxyl radical with formaldehyde

Abstract

The HO reaction of formaldehyde was studied by the FTIR spectroscopic method in the presence of 700 torr of air at 299 ± 2 K. The HO radicals were generated in the photooxidation of RONO (R = CH3 and C2H5), and 13C-labeled formaldehyde (13CH2O) was employed as the reactant. Of the two exothermic reaction paths for the HO-CH2O reaction, only channel 1a was shown to be operative: HO + CH2O → CHO + H2O (1a); HO + CH2O → HC(O)OH + H (1b). An average value of k(HO+CH2O)/k(HO+C2H4) = 0.99 ± 0.06 (3σ) was determined by the competitive kinetic method. This value combined with k(HO+C2H4) = [8.48 ± 0.60 (3σ)] × 10-12 cm3 molecule-1 s-1 gives k(HO+CH2O) = (8.4 ± 1.1) × 10-12 cm3 molecule-1 s-1, in good agreement with recent direct measurements in diluent Ar at ≤40 torr. © 1984 American Chemical Society.