title: Site-specific rate constant measurements for primary and secondary H- and D-abstraction by OH radicals: propane and n-butane.
abstract: Site-specific rate constants for hydrogen (H) and deuterium (D) abstraction by hydroxyl (OH) radicals were determined experimentally by monitoring the reaction of OH with two normal and six deuterated alkanes. The studied alkanes include propane (C3H8), propane 2,2 D2 (CH3CD2CH3), propane 1,1,1-3,3,3 D6 (CD3CH2CD3), propane D8 (C3D8), n-butane (n-C4H10), butane 2,2-3,3 D4 (CH3CD2CD2CH3), butane 1,1,1-4,4,4 D6 (CD3CH2CH2CD3), and butane D10 (C4D10). Rate constant measurements were carried out over 840-1470 K and 1.2-2.1 atm using a shock tube and OH laser absorption. Previous low-temperature data were combined with the current high-temperature measurements to generate three-parameter fits which were then used to determine the site-specific rate constants. Two primary (P1,H and P1,D) and four secondary (S00,H, S00,D, S01,H, and S01,D) H- and D-abstraction rate constants, in which the subscripts refer to the number of C atoms connected to the next-nearest-neighbor C atom, are obtained. The modified Arrhenius expressions for the six site-specific abstractions by OH radicals are P1,H = 1.90 × 10(-18)T(2.00) exp(-340.87 K/T) cm(3) molecule(-1) s(-1) (210-1294 K); P1,D = 2.72 × 10(-17) T(1.60) exp(-895.57 K/T) cm(3) molecule(-1) s(-1) (295-1317 K); S00,H = 4.40 × 10(-18) T(1.93) exp(121.50 K/T) cm(3) molecule(-1) s(-1) (210-1294 K); S00,D = 1.45 × 10(-20) T(2.69) exp(282.36 K/T) cm(3) molecule(-1) s(-1) (295-1341 K); S01,H = 4.65 × 10(-17) T(1.60) exp(-236.98 K/T) cm(3) molecule(-1) s(-1) (235-1407 K); S01,D = 1.26 × 10(-18) T(2.07) exp(-77.00 K/T) cm(3) molecule(-1) s(-1) (294-1412 K).
authors.affiliation: Clean Combustion Research Center, Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955, Saudi Arabia.
authors.forename: Jihad
authors.initials: J
authors.lastname: Badra
authors.forename: Ehson F
authors.initials: EF
authors.lastname: Nasir
authors.forename: Aamir
authors.initials: A
authors.lastname: Farooq