Reaction of ethyl radicals with hydrogen and deuterium

Abstract

Studies of the relative yields of CzH4 and C2H6 produced in the oxidation of propionaldehyde at 440°C in the presence and absence of Hn or D2 have enabled the velocity constant ratios ka/k14

Addition of ethane to slowly reacting mixtures of hydrogen and oxygen at 500°C

“…This agrees closely with a value of k Z 2 = 2.36 x los at 500°C obtained from the Arrhenius parameters derived by Baldwin and Melvin 2 3 from data on kz2 between 30 and 1280°C. Particularly in view of the fact that reaction (22) is less important than (21) in removing CzH6 in the present study, the good agreement confirms the reliability of the method as a means of studying radical reactions.…”

“…Since this value is much less than the value of 146 required to explain the results, whereas the present value of k2Jk2 agrees closely with that obtained from inhibition studies, it is probable that reaction (24) is of little importance. In confirmation of this view, it is only possible to obtain a pressure dependence for (AH& of slightly greater than unity if reaction (22) is included in the mechanism.…”

“…The ratio k2,/k, is insensitive to whether (22) or ( 24) is the minor reaction removing C2H6 ; if Since the evidence indicates that (24) is unimportant, combination of k2,/k, = 10.9 * with the most recent estimate of k , = 2.3 x 10" (exp -5200/RT), gives kZl = 8.5 x lo9 1. mol-l s-l at 500°C. Greiner used vacuum ultra-violet flash-photolysis of H 2 0 + Ar mixtures to produce OH radicals, and obtained k z l = 1.76(+0.23) x lo8 1. mol-I s-l at 29°C.…”

Molecular mechanisms in the pyrolysis of unsaturated chlorinated hydrocarbons

“…In particular, the formation of new products or a change in product distribution on co-pyrolysis with H 2 or D 2 is strong indirect evidence for the involvement of free radicals. This well-established method is based on the rapid reaction of many radicals with H 2 : R + H 2 -RH + H. [36][37][38] We have exploited this to demonstrate, for example, the role played by thienyl radicals in the decomposition of thiophene. 39…”

Kinetic parameters of the deuterium+oxygen reaction

“…A similar reduction is found in the reaction of C2H, radicals with H2 and D2, and other examples are quoted in ref. (35).…”