H-shift and cyclization reactions in unsaturated alkylperoxy radicals near room temperature: propagating or terminating autoxidation?

The autoxidation of alkylperoxy radicals (RO, where R is organic) is an important degradation pathway for organic compounds in a wide range of chemical systems including Earth's atmosphere. It is thought to proceed by internal H-shift reactions and, for unsaturated radicals, cyclization. However, experimental data on specific reactions steps for unsaturated RO is scarce.

Correction: Impact of temperature-dependent non-PAN peroxynitrate formation, RONO, on nighttime atmospheric chemistry.

Correction for 'Impact of temperature-dependent non-PAN peroxynitrate formation, RONO, on nighttime atmospheric chemistry' by Michelle Färber , , 2024, https://doi.org/10.1039/d3cp04163h.

Impact of temperature-dependent non-PAN peroxynitrate formation, RONO, on nighttime atmospheric chemistry.

The formation of peroxynitrates (RONO) from the reaction of peroxy radicals (RO) and nitrogen dioxide (NO) and their subsequent redissociation are typically not included in chemical mechanisms. This is often done to save computational time as the assumption is that the equilibrium is strongly towards the RO + NO reaction for most conditions. Exceptions are the reactions of the methyl peroxy radical due to its abundance in the atmosphere and of acyl-RO radicals due to the long lifetime of peroxyacyl nitrates RONO (PANs).

A Four Carbon Organonitrate as a Significant Product of Secondary Isoprene Chemistry.

Oxidation of isoprene by nitrate radicals (NO) or by hydroxyl radicals (OH) under high NO conditions forms a substantial amount of organonitrates (ONs). ONs impact NO concentrations and consequently ozone formation while also contributing to secondary organic aerosol. Here we show that the ONs with the chemical formula CHNO are a significant fraction of isoprene-derived ONs, based on chamber experiments and ambient measurements from different sites around the globe.