The gas-phase pyrolysis of alkyl nitrites. VII. Primary and secondary nitrites in the presence of nitric oxide

0538-8066

Chemistry ; Physical Chemistry

Wiley InterScience Backfile Collection 1832-2000

Chemistry and Pharmacology

Although our pyrolytic studies of five alkyl nitrites (RONO) have shown that it is possible to determine precise, acceptable values for k1: we have been uncertain about the mechanism for the first order production of nitroxyl from primary and secondary nitrites. Nitroxyl could arise either from the direct elimination process (5) or from the disproportionation of the alkoxyl radical concerned and nitric oxide: Thus kexp = k5 or k1k6/[k2 + k6]. If the route is reaction (6), Eexp should be identical to E1, since the ratio k6/k2 is temperature independent. We preferred the elimination process because Eexp 〈 E1 and Aexp was in agreement with transition-state calculations for such elimination processes. This study was concerned with the pyrolyses of ethyl and i-propyl nitrites in the presence of nitric oxide. The results show that nitroxyl is produced via the disproportionation of the alkoxyl radical and nitric oxide, as originally suggested by Levy. This is supported by the wealth of particularly photochemical data in the literature. Our and other previous spuriously low Arrhenius parameters are attributed to heterogeneous effects.

3 Ill.

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