Rate Constants and CH₃O Product Yield of the Reaction OH + CH₃OH → Products

Abstract

Absolute rate constants and CH,O product yield for the reaction of OH radicals with methanol have been determined using a combined laser photolysis/resonance fluorescence (laser induced fluorescence) technique. The rate coefficient for total OH (k, = k, + k2) is found to be k, = (1.2 i 0.3). lo-" exp[-(810 * 50) K/T] cm3/molecule. s over the temperature range 295-420 K. -The branching ratio of CH,O formation, 9 = k, /k, + k,, where (1) OH + CH,OH -+ CH,O + H,O and (2) OH + CH,OH -+ CH20H + H,O, is found to be 0. 1 1 f 0.03 and 0.22 f 0.07 at 298 and 393 K, respectively. From the temperature dependence of 9 it is predicted that channel (1) is dominant in the combustion temperature region.

Absolute and relative rate constants for the reactions of hydroxyl radicals and chlorine atoms with a series of aliphatic alcohols and ethers at 298 K

“…2 kcal mol-' and D(CH30-H) = 104 k 1 kcal mol-' 1421. The available evidence suggests [22,[25][26][27],431 that abstraction from the alcohol group in CH30H accounts for a maximum of 15% of the products at room temperature for reaction with OH radicals although the corresponding reaction with C1 atoms appears to occur exclusively from the C-H bonds [38]. The contribution to the overall rate constant for reaction of OH radicals with the higher members of the aliphatic alcohol series from abstraction at the OH group is likely to be less significant.…”

Rate Constants and Vinoxy Product Yield in the Reaction OH + Ethylene Oxide

“…Its output was directed into the reaction cell coaxially with the photolysis laser beam. In order to obtain the time dependence of the vinoxy concentration the delay time I'i./ between both lasers was varied, usually between 0.2 -20 ms. A detailed description of this technique has recently been given (7).…”

A shock tube study of the reactions of the hydroxyl radical with several combustion species

“…Hagele et al [47] studied the reaction over the temperature range of 295 < T/K < 420 by laser photolysis/resonance fluorescence, and found the total rate coefficient to be 7.2 x 10l2 exp( -810/T), with the branching fraction kga/ks,total = 0.11 at 298 K and 0.22 at 393 K.…”

“…We have carried out TST calculations for the two reaction channels, assuming the ratio of kga/kkb (298) determined by Hagele et al [47] and starting with a model similar to that used previously for OH + ethane [17]. In order to obtain agreement with our shock tube result, it was necessary to make the activated complex for abstraction from the methyl group very stiff (all vibrational frequencies above 900 cm-'), es had previously been found necessary in modeling the OH + CH4 reaction [53].…”