The hydroxyl radical reaction rate constant and products of methyl isobutyrate

The relative rate technique has been used to measure the rate coefficient for the reaction of the hydroxyl radical (OH) with methyl isobutyrate (MIB, (CH3)2 CHC(O)OCH3) to be (1.7 ± 0.4) × 10−12cm3molecule−1s−1 at 297 ± 3 K and 1 atmosphere total pressure. To more clearly define MIB's atmospheric degradation mechanism, the products of the OH + MIB reaction were also determined. The observed products and their yields were: acetone (97 ± 1%, (CH3)2C(O)) and methyl pyruvate (MP, 3.3 ± 0.3%, CH3C(O)C(O)OCH3). The products' formation pathways are discussed in light of current understanding of the atmospheric chemistry of oxygenated organic compounds.