Study of the long-lived intermediate formed in the photoreduction of benzophenone by isopropyl alcohol

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Abstract

The formation, structure and decay kinetics of the long-lived intermediate formed in the photoreduction of benzophenone by isopropyl alcohol in acetonitrile has been investigated. Laser flash photolysis and transient absorption measurements carried out with the benzophenone-isopropyl alcohol-acetonitrile and benzophenone-benzhydrol-acetonitrile systems indicated that the intermediate, generally called a "light-absorbing transient" (LAT), is formed by coupling of a diphenylketyl with a dimethylketyl radical. Dimerization of diphenylketyl radicals appeared to contribute very little to LAT formation. Study of the decay kinetics of the intermediate revealed that LAT actually consisted of a mixture of an ortho and a para isomer for which absorption spectra could be obtained. The ortho-LAT isomer decomposed faster, mainly by a benzophenone-enhanced process, and absorbed at longer wavelengths with a maximum at 358 nm, while para-LAT isomer decayed more slowly and had an absorption maximum at 317 nm. Additional investigations supplied absolute spectra for short-lived transients, i.e. for benzophenone and acetone triplet states and diphenylketyl and dimethylketyl radicals.

Original languageEnglish
Pages (from-to)27-40
Number of pages14
JournalJournal of Photochemistry and Photobiology A: Chemistry
Volume46
Issue number1
DOIs
Publication statusPublished - 1989

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isopropyl alcohol
2-Propanol
photochemical reactions
Alcohols
acetonitrile
isomers
Acetonitrile
Isomers
kinetics
decay
dimerization
acetone
atomic energy levels
flash
photolysis
Kinetics
Dimerization
Photolysis
benzophenone
Acetone

ASJC Scopus subject areas

  • Bioengineering
  • Physical and Theoretical Chemistry

Cite this

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title = "Study of the long-lived intermediate formed in the photoreduction of benzophenone by isopropyl alcohol",
abstract = "The formation, structure and decay kinetics of the long-lived intermediate formed in the photoreduction of benzophenone by isopropyl alcohol in acetonitrile has been investigated. Laser flash photolysis and transient absorption measurements carried out with the benzophenone-isopropyl alcohol-acetonitrile and benzophenone-benzhydrol-acetonitrile systems indicated that the intermediate, generally called a {"}light-absorbing transient{"} (LAT), is formed by coupling of a diphenylketyl with a dimethylketyl radical. Dimerization of diphenylketyl radicals appeared to contribute very little to LAT formation. Study of the decay kinetics of the intermediate revealed that LAT actually consisted of a mixture of an ortho and a para isomer for which absorption spectra could be obtained. The ortho-LAT isomer decomposed faster, mainly by a benzophenone-enhanced process, and absorbed at longer wavelengths with a maximum at 358 nm, while para-LAT isomer decayed more slowly and had an absorption maximum at 317 nm. Additional investigations supplied absolute spectra for short-lived transients, i.e. for benzophenone and acetone triplet states and diphenylketyl and dimethylketyl radicals.",
author = "A. Demeter and T. B{\'e}rces",
year = "1989",
doi = "10.1016/1010-6030(89)87030-3",
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pages = "27--40",
journal = "Journal of Photochemistry and Photobiology A: Chemistry",
issn = "1010-6030",
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TY - JOUR

T1 - Study of the long-lived intermediate formed in the photoreduction of benzophenone by isopropyl alcohol

AU - Demeter, A.

AU - Bérces, T.

PY - 1989

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N2 - The formation, structure and decay kinetics of the long-lived intermediate formed in the photoreduction of benzophenone by isopropyl alcohol in acetonitrile has been investigated. Laser flash photolysis and transient absorption measurements carried out with the benzophenone-isopropyl alcohol-acetonitrile and benzophenone-benzhydrol-acetonitrile systems indicated that the intermediate, generally called a "light-absorbing transient" (LAT), is formed by coupling of a diphenylketyl with a dimethylketyl radical. Dimerization of diphenylketyl radicals appeared to contribute very little to LAT formation. Study of the decay kinetics of the intermediate revealed that LAT actually consisted of a mixture of an ortho and a para isomer for which absorption spectra could be obtained. The ortho-LAT isomer decomposed faster, mainly by a benzophenone-enhanced process, and absorbed at longer wavelengths with a maximum at 358 nm, while para-LAT isomer decayed more slowly and had an absorption maximum at 317 nm. Additional investigations supplied absolute spectra for short-lived transients, i.e. for benzophenone and acetone triplet states and diphenylketyl and dimethylketyl radicals.

AB - The formation, structure and decay kinetics of the long-lived intermediate formed in the photoreduction of benzophenone by isopropyl alcohol in acetonitrile has been investigated. Laser flash photolysis and transient absorption measurements carried out with the benzophenone-isopropyl alcohol-acetonitrile and benzophenone-benzhydrol-acetonitrile systems indicated that the intermediate, generally called a "light-absorbing transient" (LAT), is formed by coupling of a diphenylketyl with a dimethylketyl radical. Dimerization of diphenylketyl radicals appeared to contribute very little to LAT formation. Study of the decay kinetics of the intermediate revealed that LAT actually consisted of a mixture of an ortho and a para isomer for which absorption spectra could be obtained. The ortho-LAT isomer decomposed faster, mainly by a benzophenone-enhanced process, and absorbed at longer wavelengths with a maximum at 358 nm, while para-LAT isomer decayed more slowly and had an absorption maximum at 317 nm. Additional investigations supplied absolute spectra for short-lived transients, i.e. for benzophenone and acetone triplet states and diphenylketyl and dimethylketyl radicals.

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