Rate Constants and Mechanism for Reactions of Ketenes with OH Radicals in Air at 299 +/- 2K

Article abstract of DOI:10.1246/bcsj.58.2157

Rate constants for reactions of OH radicals with four kinds of simple ketenes (ketene, methylketene: MK, ethyketene: EK, and dimethylketene: DMK) were measured in 1 atm of air at 299 +/- 2K by use of a competitive reaction method.The photolysis of CH3ONO in air was used to generate OH radicals.The rate constants for OH reactions obtained are (1.8+/-0.2)x10^-11, (7.6+/-1.4)x10^-11, (11+/-3)x10^-11 and (10+/-3)x10^-11 cm³ molecule^-1s^-1 for ketene, MK, and DMK, respectively.The major product was a carbonyl compound; HCHO from ketene, CH3CHO from MK, and CH3COCH3 from DMK; the yield was cca. 80percent, 72+/-17percent, and 70+/-3percent respectively.t is proposed that the reaction proceeded mainly via an OH addition to the olefinic carbons of ketenes and the adduct decomposes to give a carbonyl compound and CO as final products in air.