Kinetics and mechanisms of the reactions of hydroxyl radicals and hydrated electrons with nitrosamines and nitramines in water.
Absolute rate constants for hydroxyl radical, *OH, and hydrated electron, e(aq)(-), reactions with low-molecular-weight nitrosamines and nitramines in water at room temperature were measured using the techniques of electron pulse radiolysis and transient absorption spectroscopy. The bimolecular rate constants obtained, k (M(-1) s(-1)), for e(aq)(-) and *OH reactions, respectively, were as follows: methylethylnitrosamine, (1.67 +/- 0.06) x 10(10) and (4.95 +/- 0.21) x 10(8); diethylnitrosamine, (1.61 +/- 0.06) x 10(10) and (6.99 +/- 0.28) x 10(8); dimethylnitramine, (1.91 +/- 0.07) x 10(10) and (5.44 +/- 0.20) x 10(8); methylethylnitramine, (1.83 +/- 0.15) x 10(10) and (7.60 +/- 0.43) x 10(8); and diethylnitramine, (1.76 +/- 0.07) x 10(10) and (8.67 +/- 0.48) x 10(8), respectively. MNP/DMPO spin-trapping experiments demonstrated that hydroxyl radical reaction with these compounds occurs by hydrogen atom abstraction from an alkyl group, while the reaction of the hydrated electron was to form a transient radical anion. The latter adduct formation implies that the excess electron could subsequently be transferred to regenerate the parent chemical, which would significantly reduce the effectiveness of any free-radical-based remediation effort on nitrosamine/nitramine-contaminated waters.
Mezyk
Stephen P
SP
Department of Chemistry and Biochemistry, California State University at Long Beach, 1250 Bellflower Blvd, 90840, USA. smezyk@csulb.edu
Ewing
Daryl B
DB
Kiddle
James J
JJ
Madden
Keith P
KP
D000814:Aniline Compounds / Q000737:chemistry*; D004583:Electrons; D005609:Free Radicals / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D006900:Hydroxylation; D007700:Kinetics; D009578:Nitrobenzenes / Q000737:chemistry*; D009602:Nitrosamines / Q000737:chemistry*; D010315:Particle Accelerators; D011675:Pulse Radiolysis; D014867:Water / Q000737:chemistry*
D000814:Aniline Compounds; D005609:Free Radicals; D009578:Nitrobenzenes; D009602:Nitrosamines; D014867:Water; D017665:Hydroxyl Radical; C015384:nitramine