Gas‐phase reactions of azulene with OH and NO 3 radicals and O 3 at 298 ± 2 K

Azulene, which is isomeric with naphthalene, was studied to determine whether it behaves like a polycyclic aromatic hydrocarbon or an alkene in its gas‐phase reactions with OH and NO 3 radicals and O 3 . Using relative rate methods, rate constants for the reactions of azulene with OH and NO 3 radicals and O 3 of (2.73 ± 0.56) × 10 −10 cm 3 molecule −1 s −1 , (3.9   −1.4 +2.0 ) × 10 −10 cm 3 molecule −1 s −1 , and <7 × 10 −17 cm 3 molecule −1 s −1 , respectively, were obtained at 298 ± 2 K. The observation that the NO 3 radical reaction did not involve NO 2 in the rate determining step indicates that azulene behaves more like an alkene than a polycyclic aromatic hydrocarbon in this reaction. No conclusive evidence for the formation of nitroazulene(s) from either the OH or NO 3 radical‐initiated reaction of azulene (in the presence of NO x ) was obtained.