Jump to main content
Jump to site search

Issue 2, 2019
Previous Article Next Article

Laser flash photolysis study of the photoinduced oxidation of 4-(dimethylamino)benzonitrile (DMABN)

Author affiliations

Abstract

Aromatic amines are aquatic contaminants for which phototransformation in surface waters can be induced by excited triplet states of dissolved organic matter (3DOM*). The first reaction step is assumed to consist of a one-electron oxidation process of the amine to produce its radical cation. In this paper, we present laser flash photolysis investigations aimed at characterizing the photoinduced, aqueous phase one-electron oxidation of 4-(dimethylamino)benzonitrile (DMABN) as a representative of this contaminant class. The production of the radical cation of DMABN (DMABN˙+) after direct photoexcitation of DMABN at 266 nm was confirmed in accord with previous experimental results. Moreover, DMABN˙+ was shown to be produced from the reactions of several excited triplet photosensitizers (carbonyl compounds) with DMABN. Second-order rate constants for the quenching of the excited triplet states by DMABN were determined to fall in the range of 3 × 107–5 × 109 M−1 s−1, and their variation was interpreted in terms of electron transfer theory using a Rehm–Weller relationship. The decay kinetics of DMABN˙+ in the presence of oxygen was dominated by a second-order component attributed to its reaction with the superoxide radical anion (O2˙). The first-order rate constant for the transformation of DMABN˙+ leading to photodegradation of DMABN was estimated not to exceed ≈5 × 103 s−1.

Graphical abstract: Laser flash photolysis study of the photoinduced oxidation of 4-(dimethylamino)benzonitrile (DMABN)

Back to tab navigation

Supplementary files

Publication details

The article was received on 14 Nov 2018, accepted on 13 Dec 2018 and first published on 13 Dec 2018


Article type: Paper
DOI: 10.1039/C8PP00519B
Photochem. Photobiol. Sci., 2019,18, 534-545

  •   Request permissions

    Laser flash photolysis study of the photoinduced oxidation of 4-(dimethylamino)benzonitrile (DMABN)

    F. Leresche, L. Ludvíková, D. Heger, P. Klán, U. von Gunten and S. Canonica, Photochem. Photobiol. Sci., 2019, 18, 534
    DOI: 10.1039/C8PP00519B

Search articles by author

Spotlight

Advertisements