Issue 10, 2002

Photoreduction of nitronaphthalenes in benzene by N,N-dialkylanilines and triethylamine: a time-resolved UV–vis spectroscopic study

Abstract

The triplet state of 1-methoxy-4-nitronaphthalene and 1- and 2-nitronaphthalene in benzene at room temperature was studied by time-resolved UV–vis spectroscopy with ns laser pulses at 354 nm. The triplet state reacts with N,N-dimethylaniline and N,N-diethylaniline; the rate constant is close to the diffusion-controlled limit. A transient with a peak at 340 nm is attributed to the α-aminoalkyl radical, PhN(R)˙CHR′, being formed by H-atom transfer from the dialkylaniline. Decay of this radical takes place within a few μs, as observed by bleaching in the 340–410 nm range. Thereby, a nitronaphthalene is eventually converted into stable products, such as nitrosonaphthalene, and dealkylation of the dialkylaniline occurs. Triplet quenching by triethylamine yields the radical anion, ArNO2˙, as an intermediate in acetonitrile and the conjugate acid, Ar˙NO2H, in benzene. These radicals are suggested to ultimately yield nitrosonaphthalenes by slow termination in the ms time range. Decomposition of the three nitronaphthalenes in benzene takes place in the presence of the three amines with maximum quantum yields of 0.1–0.3. The mechanisms of photodemethylation of the dialkylanilines and the photoreduction reactions of the nitronaphthalenes are discussed.

Graphical abstract: Photoreduction of nitronaphthalenes in benzene by N,N-dialkylanilines and triethylamine: a time-resolved UV–vis spectroscopic study

Article information

Article type
Paper
Submitted
21 Mar 2002
Accepted
10 Jul 2002
First published
14 Aug 2002

J. Chem. Soc., Perkin Trans. 2, 2002, 1778-1783

Photoreduction of nitronaphthalenes in benzene by N,N-dialkylanilines and triethylamine: a time-resolved UV–vis spectroscopic study

H. Görner, J. Chem. Soc., Perkin Trans. 2, 2002, 1778 DOI: 10.1039/B202889C

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Spotlight

Advertisements