x21b5; Reactions of C12-C14n-Alkylcyclohexanes with Cl Atoms: Kineticsand Secondary Organic Aerosol Formation

Long-chain alkanes are a type of intermediatevolatility organic compound (IVOC) in the atmosphere and apotential source of secondary organic aerosols (SOAs). C12-C14n-alkylcyclohexanes are important compositions of IVOCs, withconsiderable concentrations and emission rates. The reaction rateconstants and SOA formation of the reactions of C12-C14n-alkylcyclohexanes with Cl atoms were investigated in the presentstudy. The reaction rate constants of the long-chain alkanesobtained via the relative-rate method at 298 +/- 0.2 K (in units ofx10-10cm3molecule-1s-1) were as follows:khexylcyclohexane= 5.11 +/- 0.28,kheptylcyclohexane= 5.56 +/- 0.30, andkoctylcyclohexane= 5.74 +/- 0.31.The gas-phase products of the reactions were identified as mainlysmall molecules of aldehydes, ketones, and acids. The particle-phase products were mostly monomers and oligomers, but therewere still trimers even under high-NOxconditions. Moreover, under high-NOxconditions (urban atmosphere), the SOA yields ofhexylcyclohexane are higher than that under low-NOxconditions (remote atmosphere), indicating that more attention should begiven to the SOA formation of Cl-initiatedn-alkylcyclohexane oxidations in polluted regions. This research can further clarify theoxidation processes and SOA formation ofn-alkylcyclohexanes in the atmosphere.

Automated summary

This study investigated the reaction rate constants and secondary organic aerosol (SOA) formation of long-chain alkanes reacting with chlorine atoms in the atmosphere. The gas-phase products were identified as aldehydes, ketones, and acids, while the particle-phase products were mostly monomers and oligomers. The study found that the SOA yields were higher under high-NOx conditions.