Different reaction mechanisms of diphenylether and 4-bromodiphenylether with nitrous acid in the 355 nm laser flash photolysis of mixed aqueous solution

Abstract

The microscopic reaction mechanisms of diphenylether (DPE) and 4-bromodiphenylether (4-BrDPE) with nitrous acid (HNO 2) in the absence of O 2 have been explored by the 355 nm laser flash photolysis. It was proposed that OH radical, from the photolysis of HNO 2, added to DPE forms the C 12H 10O–OH adduct while added to 4-BrDPE forms the 4-BrDPE–OH and 4-BrOH–DPE adducts. The first-order decay rate constants of the C 12H 10O–OH adduct, 4-BrDPE–OH adduct and 4-BrOH–DPE adduct were measured to be (1.86 ± 0.14) × 10 5 s −1, (2.19 ± 0.04) × 10 5 s −1 and (1.56 ± 0.03) × 10 5 s −1, respectively. The final photolysis products of DPE and HNO 2 identified by GC/MS analysis were phenol, o-hydroxydiphenylether, p-hydroxydiphenylether and p-nitrodiphenylether, while the final photolysis product of 4-BrDPE and HNO 2 identified by LC/MS analysis was mainly the dimer.