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Radical‐Pair Formation in Hydrocarbon (Aut)Oxidation
Author(s) -
Sandhiya Lakshmanan,
Zipse Hendrik
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901415
Subject(s) - chemistry , homolysis , radical , toluene , photochemistry , hydrogen atom abstraction , bond cleavage , benzaldehyde , dissociation (chemistry) , substituent , molecule , hydrocarbon , catalysis , medicinal chemistry , organic chemistry
The reaction profiles for the uni‐ and bimolecular decomposition of benzyl hydroperoxide have been studied in the context of initiation reactions for the (aut)oxidation of hydrocarbons. The unimolecular dissociation of benzyl hydroperoxide was found to proceed through the formation of a hydrogen‐bonded radical‐pair minimum located +181 kJ mol −1 above the hydroperoxide substrate and around 15 kJ mol −1 below the separated radical products. The reaction of toluene with benzyl hydroperoxide proceeds such that O−O bond homolysis is coupled with a C−H bond abstraction event in a single kinetic step. The enthalpic barrier of this molecule‐induced radical formation (MIRF) process is significantly lower than that of the unimolecular O−O bond cleavage. The same type of reaction is also possible in the self‐reaction between two benzyl hydroperoxide molecules forming benzyloxyl and hydroxyl radical pairs along with benzaldehyde and water as co‐products. In the product complexes formed in these MIRF reactions, both radicals connect to a centrally placed water molecule through hydrogen‐bonding interactions.