Slow oxidation of ethane and ethylene in the gas phase. Part 2.—Analytical features

Abstract

From detailed analysis of the initial stages of the oxidation of ethane, water, ethylene and formaldehyde are the only significant initial products at 362" and acetaldehyde is an additional initial product at 31 8". Methanol, ethanol, ethylene oxide, carbon monoxide and carbon dioxide are secondary products. As oxygen has no effect on the relative yields of initial products they are produced by reactions of the same kinetics. Between 362 and 318" there is a profound change in the distribution of initial products. It is proposed that the equilibrium (1) is established(1) and that ethylene is formed by direct H atom abstraction from ethyl while formaldehyde is formed from the ethyl peroxy radical.The initial products from the oxidation of ethylene are ethylene oxide, formaldehyde and acetaldehyde. The secondary products are the same as from ethane. Various possible mechanisms are discussed for their formation. It is concluded that HO2 is the main radical attacking ethylene. The end products of the oxidations are methane, ethane (from ethylene) and ethanol.

Absolute rate constants for hydrocarbon autoxidation. V. The hydroperoxy radical in chain propagation and termination

“…Dorfman et al's (42) study of the kinetics of radical disappearance and of the products formed during the pulse radiolysis of aerated aqueous solutions of benzene suggest that cyclohexadienyl peroxy radicals are the initial product from reaction [3], i.e.7…”

“…For reaction [3], With saturated alkyl radicals AHrO for reaction [8] is about -2s kcal/mole (e.g. O .…”

“…The heat of reaction [3] (AHrO) and of the more usual propagation reaction, can be calculated from Benson's compilations of bond dissociatio~l energies (DHO) and heats of formation of the various species involved (29, 30). For reaction [3], With saturated alkyl radicals AHrO for reaction [8] is about -2s kcal/mole (e.g.…”

“…In the gas phase oxidation of simple alkanes above 300 "C the major initial products are olefins containing the same number of carbon atoms as the parent alkanes (1)(2)(3). This has been explained in terms of a hydroperoxy radical chain, e.g.…”

The C2H5 + O2 Reaction Mechanism: High-Level ab Initio Characterizations

“…The work of Knox and Wells [34][35][36] in the mid-1960s supported this bimolecular mechanism at temperatures between 598 and 698 K, and bimolecular abstraction was assumed in many subsequent studies. [37][38][39][40][41] Over the range of 698-838 K, Baldwin et al 41 in 1980 suggested an activation energy of 3.9 kcal mol -1 for M1.…”