Investigations into the gas-phase photolysis and OH radical kinetics of nitrocatechols: implications of intramolecular interactions on their atmospheric behaviour

Abstract. The Environmental Simulation Chamber made of Quartz from the University “Alexandru Ioan Cuza” (ESC-Q-UAIC), at Iasi, Romania, was used to investigate gas-phase reaction rate coefficients for four nitrocatechols toward OH radicals under simulated atmospheric conditions. Employing relative techniques a temperature 298 ± 2 K and total air pressure 1 atm, obtained (in 10?12 cm3 s?1) were as follows: k3NCAT = (3.41 0.37) 3-nitrocatechol k5M3NCAT (5.55 0.45) 5-methyl-3-nitrocatechol 365 nm, using CH3ONO photolysis source dimethyl ether cyclohexane reference compounds, k4NCAT (1.27 0.19) 4-nitrocatechol k4M5NCAT (0.92 0.14) 4-methyl-5-nitrocatechol 254 nm H2O2 methanol compounds. rates in actinic region, scaled relevant conditions by NO2 photolysis, evaluated 5-methyl-3-nitrocatechol: J3NCAT (3.06 0.16) × 10?4 s?1 J5M3NCAT (2.14 0.18) s?1, respectively. constants measured values are J4NCAT (6.7 0.1) 10?5 J4M5NCAT (3.2 0.3) s?1. Considering results, our study suggests that may be main degradation process atmosphere, with photolytic lifetime atmosphere up h. Results discussed terms reactivity investigation OH-radical-initiated oxidation their structural features. coefficient also compared those estimated structure-activity relationship monocyclic aromatic hydrocarbons assessed relation IR spectra. Additional comparison similar compounds is presented, underlining implications possible pathways behaviour.