Experimental and Theoretical Investigation of 2-Methylbenzothiazole Oxidation by OH in Air and the Role of O

Benzothiazoles are in widespread use as components of, or precursors to, a variety of consumer and industrial products. This class of compounds encompasses the simplest molecule benzothiazole (BTH) in which a benzene ring is fused to a thiazole ring, as well as a series of derivatives which are commonly functionalized at the C2 position of the thiazole ring. The addition of groups at this position modifies the reactivity in ways that are not well-known. While the reactions of benzothiazoles in water have been the subject of investigation, in part for wastewater treatment applications, much less is known about their atmospheric reactions where gas phase oxidation by the OH radical is expected to dominate. We report here studies of the kinetics, products, and mechanism of reaction of 2-methylbenzothiazole (MeBTH) with OH in the gas phase using a combination of experiments and theory. Comparison to previous studies of the OH oxidation of BTH highlights the impact of substitution of a methyl group at the 2-position on the products and reactivity. Specifically, the rate constant at 298 K and 1 atm pressure for the MeBTH-OH reaction is (3.0 ± 0.4) × 10