Observing elusive tetroxides in gas-phase radical reactions supports the Russell mechanism

TL;DR

Scientists observed elusive tetroxide intermediates in radical reactions, supporting a long-debated chemical mechanism from 1957.

Contribution

First direct observation of tetroxides in gas-phase RO2 radical reactions, confirming the Russell mechanism.

Findings

Tetroxides were observed in gas-phase reactions of RO2 radicals using direct mass spectrometry.

The lifetime of CH3OOOOCH3 was estimated between 0.2 and 200 milliseconds, supporting the Russell mechanism.

Abstract

Organic peroxy radicals (RO2) are important intermediates for oxidation processes in aerobic chemical systems. Their self- and “cross”-reactions (i.e., with themselves and other RO2) are increasingly receiving attention in a wide range of applications, from atmospheric chemistry to cancer therapies. However, their mechanism has been debated for decades. The Russell mechanism, widely assumed for these reactions today, is characterized by a tetroxide intermediate, only observed once and partially since its postulate in 1957. Here we report the observation of tetroxides in the gas-phase reactions of different RO2 by direct mass spectrometry, in which ionic and gas-phase dimerization could be ruled out. Within the uncertainties in the kinetic profiles, the lifetime for CH3OOOOCH3 was determined to be in the range 0.2 and 200 milliseconds, consistent with an intermediate and supporting the Russell mechanism.

Organic tetroxides were observed in gas-phase reactions of RO2 radicals, supporting the Russell mechanism postulated in 1957.

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