Atmospheric chemistry of i-butanol

Article abstract of DOI:10.1021/jp107950d

Smog chamber/FTIR techniques were used to determine rate constants of k(Cl + i-butanol) = (2.06 ± 0.40) × 10^-10, k(Cl + i-butyraldehyde) = (1.37 ± 0.08) × 10^-10, and k(OH + i-butanol) = (1.14 ± 0.17) × 10^-11 cm³ molecule^-1 s^-1 in 700 Torr of N₂/O₂ diluent at 296 ± 2K. The UV irradiation of i-butanol/Cl ₂/N₂ mixtures gave i-butyraldehyde in a molar yield of 53 ± 3%. The chlorine atom initiated oxidation of i-butanol in the absence of NO gave i-butyraldehyde in a molar yield of 48 ± 3%. The chlorine atom initiated oxidation of i-butanol in the presence of NO gave (molar yields): i-butyraldehyde (46 ± 3%), acetone (35 ± 3%), and formaldehyde (49 ± 3%). The OH radical initiated oxidation of i-butanol in the presence of NO gave acetone in a yield of 61 ± 4%. The reaction of chlorine atoms with i-butanol proceeds 51 ± 5% via attack on the α-position to give an α-hydroxy alkyl radical that reacts with O₂ to give i-butyraldehyde. The atmospheric fate of (CH₃)₂C(O)CH ₂OH alkoxy radicals is decomposition to acetone and CH₂OH radicals. The atmospheric fate of OCH₂(CH₃)CHCH ₂OH alkoxy radicals is decomposition to formaldehyde and CH ₃CHCH₂OH radicals. The results are consistent with, and serve to validate, the mechanism that has been assumed in the estimation of the photochemical ozone creation potential of i-butanol.