Kinetics of the reactions of OH radicals with n-butyl, isobutyl, n-pentyl and 3-methyl-1-butyl nitrates

The kinetics of the reactions of n-butyl (BTN), isobutyl (IBN), n-pentyl (PTN) and 3-methyl-1-butyl (3M1BN) nitrates with OH radicals has been studied using a low pressure flow tube reactor combined with a quadrupole mass spectrometer. The rate constants of the title reactions were determined under pseudo-first order conditions from kinetics of OH consumption in high excess of the nitrates. The overall rate coefficients, ICRTN 1.0 x 10(-13)(T/298)(3.36) exp(838/T) (T = 288-500 K), k(IBN) = 2.8 x 10(-14) (71298)(4.9) exp(1127/T) (T = 283-500 K), k(PTN) = 1.26 x 10(-12) (17298)(4.56) exp(45/T) (T = 298-496 K) and k(3M1BN) = 8.47x10(-14) (T/298)(3.52) exp(1069/T) cm(3)molecule(-l)s(-1) (T = 288-538 K) (with conservative 15% uncertainty), were determined at a total pressure of 1 Torr of helium. The yields of the carbonyl compounds, nbutanal (n-C3H7CHO) and isobutanal ((CH3)(2)CHCHO), resulting from the abstraction by OH of an a hydrogen atom in n-butyl and isobutyl nitrates, followed by a-substituted alkyl radical decomposition, were determined at T = 300 K to be 0.10 +/- 0.02 and 0.15 +/- 0.03, respectively. The calculated tropospheric lifetimes of BTN, IBN, PTN and 3M1BN indicate that reaction of these nitrates with OH represents an important sink of these compounds in the atmosphere. (C) 2017 Elsevier Ltd. All rights reserved.