Products of the chlorine-atom- and hydroxyl-radical-initiated oxidation ofCH3CN

FTIR smog chamber techniques were used in the first investigation of the pr oducts following oxidation of CH3C dropN initiated by Cl atom or OH radical s in air at 296 +/- 2 K. It is shown that reaction of Cl atoms with CH3C dr opN gives (CH2C)-C-.=N radicals in essentially 100% yield. These radicals a dd O-2 to form the peroxy radical N drop CCH2O2.. Self-reaction of the pero xy radicals gives the alkoxy radical N drop CCH2O. which reacts exclusively with O-2 to give HC(O)C dropN (formyl cyanide). The reaction of Cl atoms w ith HC(O)C dropN proceeds with a rate constant of (7.0 +/- 1.0) x 10(-13) c m(3) molecule(-1) s(-1) via H-abstraction to give C-.(O)C dropN radicals wh ich add O-2 to give N drop CC(O)OO. radicals. The subsequent chemistry of t hese radicals leads to the production of HC dropN and CO2 or the acyl perox y nitrate N drop CC(O)OONO2, the IR spectrum of which is reported here. The reaction of OH radicals with CH3C dropN in 700 Torr of air gives HC(O)C dr opN in (40 +/- 20)% yield implying that up to half of the OH + CH3C dropN r eaction could proceed via H-atom abstraction, with the remaining fraction p roceeding via addition to the -C dropN group. These results are discussed i n terms of the atmospheric oxidation mechanism of CH3C dropN.