Tracking a Paterno-Buchi Reaction in Real Time Using Transient Electronic and Vibrational Spectroscopies

Stephanie J. Harris, Daniel Murdock, Michael P. Grubb, Ian P. Clark, Gregory M. Greetham, Michael Towrie, Michael N. R. Ashfold*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

4 Citations (Scopus)
254 Downloads (Pure)

Abstract

A detailed mechanistic investigation of the early stages of the Paterno-Buchi reaction following 267 nm excitation of benzaldehyde in cyclohexene has been completed using ultrafast, broadband transient UV-visible and IR absorption spectroscopies. Absorption due to electronically excited triplet state benzaldehyde decays on a 80 ps time scale via reaction with cyclohexene. The growth and subsequent decay of the biradical intermediate produced following C-O bond formation is followed by transient vibrational spectroscopy. The biradical decays by ring closure to an oxetane or by dissociating, reforming the ground state reactants. Detailed kinetic analysis allowed derivation of quantum yields and rate constants for these competing biradical decay processes, phi oxetane = 0.53, phi(diss) = 0.47, koxetane = 0.27 +/- 0.09 ns(-1) and Phi diss = 0.24 +/- 0.09 ns(-1). This study provides a striking illustration of the ways in which contemporary ultrafast transient absorption spectroscopy methods can be used to dissect the mechanism and kinetics of a classic photoreaction.

Original languageEnglish
Pages (from-to)10240-10245
Number of pages6
JournalJournal of Physical Chemistry A
Volume118
Issue number44
Early online date16 Oct 2014
DOIs
Publication statusPublished - 6 Nov 2014

Keywords

  • PHOTOCYCLOADDITION REACTIONS
  • CARBONYL-COMPOUNDS
  • DYNAMICS
  • PHOTOCHEMISTRY
  • BENZALDEHYDE
  • STEREOSELECTIVITY
  • RELAXATION

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