Transformation Reactions of Radicals from the Oxidation of Diphenhydramine: Pulse Radiolysis and Mass Spectrometric Studies

摘要

abstract_textpMechanistic aspects of diphenhydramine (DPH) oxidation induced by hydroxyl ((OH)-O-center dot) and sulfate (SO4 center dot-) radicals have been explored in detail by pulse radiolysis technique and high resolution mass spectrometry (HRMS). The transient absorption spectrum along with HRMS analysis undoubtedly established the non-position selective hydroxylation of DPH by (OH)-O-center dot (a; k(2) = (1.08 +/- 0.06) x 10(10) dm(3) mol(-1) s(-1); lambda(max): 335 nm) led to various transformation products (i - vii) including isomeric mono (Ia-d), di (IIa-c) and tri (VIIa-e) hydroxylated analogues. On the other hand, SO4 center dot- (specific one electron oxidant) ultimately generates another hydroxylated adduct radical c lambda(max): 330 nm, k(2)=(5.70 +/- 0.03) x 10(9)dm(3) mol(-1) s(-1)) which is formed as a result of preferential hydroxylation of initially formed radical cation b at ipso position. The mechanism leading to the formation of various transformation products induced by (OH)-O-center dot and SO4 center dot- are thoroughly discussed. The mechanistic findings obtained from our studies (especially in the case of less investigated oxidant like SO4(center dot-)) are capable to enrich the fundamental understanding on environmentally relevant reactions initiated by (OH)-O-center dot and SO4(center dot-)./p/abstract_text