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

摘要

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_(12)H_(10)O-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_(12)H_(10)O-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.