Photochemical processes of 1,4-benzoquinones in aqueous medium

Éva Józsa, Virág Kiss, K. Ősz

Research output: Contribution to journalArticle

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Abstract

The photochemical reactions in the aqueous solutions of 1,4-benzoquinone, 2-methyl-1,4-benzoquinone, 2,6-dimethyl-1,4-benzoquinone, 2-chloro-1,4-benzoquinone, 2,5-dichloro-1,4-benzoquinone and 2,6-dichloro-1,4-benzoquinone were investigated using three independent monitoring techniques (spectrophotometric, spectrofluorimetric and pH-stat) and two different radiation sources, a LED with emission at 400 nm and an UV-A lamp emitting at 365 nm. The aqueous photoproducts were shown to be the corresponding substituted hydroxyl-quinones and hydroquinones for all the derivatives. Fully quantitative data treatment was used in all of the experiments based on fitting the entire kinetic curved obtained. From these fits, the quantum yield of product formation and reactant loss were determined in each case. In the pH-stat experiments, the effect of pH change was also investigated for some of the derivatives. Generally, aqueous photoreactivity is increased by the presence of electron withdrawing substituents and suppressed by electron donating ones. The pH did not have a very significant influence on the course of the photoreaction alone, but it affected the observations through different acid-base equilibria of the products hydroxyl-quinones and hydroquinones.

Original languageEnglish
Pages (from-to)166-173
Number of pages8
JournalJournal of Photochemistry and Photobiology A: Chemistry
Volume360
DOIs
Publication statusPublished - Jun 1 2018

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Keywords

  • Full kinetic curve fitting
  • pH-stat
  • Photochemistry
  • Quantum yield
  • Quinone

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)
  • Physics and Astronomy(all)

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