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

The microscopic reaction mechanisms of diphenylether (DPE) and 4-bromodiphenylether (4-BrDPE) with nitrous acid (HNO2) in the absence of O2 have been explored by the 355 nm laser flash photolysis. It was proposed that OH radical, from the photolysis of HNO2, added to DPE forms the C12H10O–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 C12H10O–OH adduct, 4-BrDPE–OH adduct and 4-BrOH–DPE adduct were measured to be (1.86 ± 0.14) × 105 s−1, (2.19 ± 0.04) × 105 s−1 and (1.56 ± 0.03) × 105 s−1, respectively. The final photolysis products of DPE and HNO2 identified by GC/MS analysis were phenol, o-hydroxydiphenylether, p-hydroxydiphenylether and p-nitrodiphenylether, while the final photolysis product of 4-BrDPE and HNO2 identified by LC/MS analysis was mainly the dimer.