Atmospheric chemistry of bifunctional cycloalkyl nitrates

Reported here are some aspects of the atmospheric chemistry of the cycloalkyl nitrates trans-2-hydroxy-cyclopentyl-1-nitrate (HCPN), 2-oxo-cyclohexyl-1-nitrate (OCHN) and trans-1-methyl-cyclohexyl-1,2-dinitrate (MCHDN). Their UV absorption spectra have been measured and rate coefficients for their reaction with OH radicals have been determined at 302 K in 1000 mbar of synthetic air. The tropospheric lifetimes of the cycloalkyl nitrates have been estimated from calculations of their photolysis frequencies and first-order OH-radical loss rates. HCPN will not photolyse under atmospheric conditions and for OCHN and MCHDN 24 h globally-averaged photolysis lifetimes of 1.6 and 7.7 days, respectively, have been estimated. The globally-averaged 24 h lifetimes due to reaction with OH radicals are approximately 4 days for both HCHN and OCHN and 8 days for MCHDN. Therefore, for OCHN and MCHDN both photolysis and reaction with OH radicals will be significant atmospheric sinks. For HCHN wet deposition may also be important due to the increased solubility of this compound.