Reaction between C2H5 and

Gutman and co-workers argued strongly against any contribution from a direct molecular abstraction reaction (5Ae) and proposed a coupled mechanism which accounted for the pressure effect, negative temperature coefficient below 500 K and the unique formation of C2H4 above this temperature. 

At low temperatures and high pressures, C2H5O radicals are mainly 

Further, studies [Method III] of the addition of C2H4 and other alkenes to tetramethylbutane + O2 mixtures over the range 650-800 K have given Arrhenius parameters for the overall reaction. 

As Walker [11] has pointed out, there are many other problems associated with the Gutman mechanism, and it is very unfortunate that so mueh of the experimental work has been focused on the C2H5 -l- O2 reaetion. A number of modelling studies by Dean and co-workers [72, 73] have been interpreted as support for the Gutman mechanism, but they are usually based on uncertain thermochemical data. Walker [11] has concluded that the answer may lie in the assumption that only one potential energy surface is involved. Two recent theoretical treatments for C2H5 -f O2 [74] and CH3 -I- O2 [75] indicate the need to consider two potential energy surfaces (see Chapter 2). 

Reaction (8) has been discussed earlier. At low temperatures, ca. 600 K, it is the main source of the secondary initiation product ROOH which on homolysis gives the alkoxy and OH radicals, both of which are very reactive. The reaction is relatively slow (see earlier) and the build up to maximum concentration may take considerable time so that lengthy indue- 

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