Isomerization reactions of peroxy radicals during oxidation of long-chain hydrocarbons yield hydroperoxides, and therefore play an important role in combustion and atmospheric chemistry, because of their action as branching agents in these chain reaction processes. Different formation mechanisms and structures are involved. Three isomeric hexyl-ketohydroperoxides are formed via isomerization reactions in oxygen of either hexoxy RO or hexylperoxy RO 2 radicals. In the temperature range 373-473 K, 2-hexoxy (C 6 H 13 O) radical in O 2 /N 2 mixtures gives 2-hexanone-5-hydroperoxide via two consecutive isomerizations. The second one is a H transfer from a HC(OH) group occurring via a seven-membered ring intermediate:Its rate constant has been determined at 453 and 483 K, and the general expression can be written as k = (1.8 ± 1) × 10 10 × exp[−(14300 ± 700)/RT] s −1 (E a in cal mol −1 ) Hexylperoxy C 6 H 13 O 2 radical, present in n-hexane oxidation by oxygen/nitrogen mixtures in the temperature range 543-573 K, gives 2-hexanone-4-hydroperoxide, 3-hexanone-5-hydroperoxide, and 2-hexanone-5-hydroperoxide. The first two are formed through an

No abstract

The rate constant of the title reaction is determined during thermal decomposition of di-n-pentyl peroxide in oxygen over the temperature range The C H O9OC H 463-523 K.