Estimation of Rate Constants for Gas-Phase Reactions of Chrysene, Benz[a]anthracene, and Benzanthrone with OH and NO₃ Radicals via a Relative Rate Method in CCl₄ Liquid Phase-System

Abstract

CCl₄ liquid-phase reaction kinetics of polycyclic aromatic compounds (PACs), including chrysene (CHRY), benz[a]anthracene (BaA), and benzanthrone (BA), with NO₃ radicals were investigated at 273 K using a relative rate method with naphthalene (NA) as the reference compound. The obtained relative reaction rates of CHRY, BaA, and BA to NA were 1.76 ± 0.08, 2.27 ± 0.20, 0.75 ± 0.01, respectively. CHRY, BaA, and BA are semi-volatile PACs with four aromatic rings. They are chemically modified into mutagenic nitropolycyclic aromatic compounds via gas-phase OH or NO₃ radical-initiated reactions. Based on the PACs relative reactivity in the CCl₄ liquid phase-system, the rate constants at 298 K for the gas-phase reaction of CHRY, BaA, and BA with OH radicals and those of CHRY, BaA, and BA with NO₃ radicals were estimated to be (in cm³molecule⁻¹s⁻¹): CHRY, (4.4 ± 0.3) × 10⁻¹¹ and (9.2 ± 3.2) × 10⁻²⁸ [NO₂]; BaA, (5.3 ± 0.5) × 10⁻¹¹ and (1.3 ± 0.5) × 10⁻²⁷ [NO₂]; BA, (2.3 ± 0.1) × 10⁻¹¹ and (3.1 ± 1.1) × 10⁻²⁸ [NO₂].