Photochemical Reactions of Cl • and Cl ₂ •− with 4‐Nitrobenzoic Acid in the Liquid Phase

Reactive chlorine species (RCS), including Cl • and Cl 2 •− , and so forth, participated in numerous chemical reactions in the atmospheric liquid phase. In this study, Cl • and Cl 2 •− were generated by 365 nm UV light irradiating or 355 nm laser flash photolysis (LFP) of the mixed solution of 5 × 10 −3 mol L −1 NaNO 2 and 1 × 10 −1 mol L −1 NaCl (pH = 1.5) and explored the photochemical reactions between 4‐nitrobenzoic acid (4‐NBA) and Cl • /Cl 2 •− . The results indicated that the initial concentration of 4‐NBA and pH showed a negative correlation with the conversion of 4‐NBA, whereas Cl − exhibited a positive correlation. LFP experiments revealed that the second‐order reaction rate constant for Cl • and Cl 2 •− with 4‐NBA was 8.53 × 10 9 and 9.3 × 10 5 L mol −1 s −1 , respectively. The main conversion products of the reaction between Cl • /Cl 2 •− and 4‐NBA identified by gas chromatography‐mass spectrometry (GC‐MS) were 4‐nitrochlorobenzene, 2‐chloro‐4‐nitrobenzoic acid, and 2,6‐dichloro‐p‐nitrobenzoic acid, respectively. The reaction between Cl • /Cl 2 •− and 4‐NBA mainly included Cl addition on the phenyl ring and the hydrogen abstraction process.