I. Iwakura et al. / Chemical Physics Letters 501 (2011) 567–571
571
thermally excited reactions. The activation energy of the classical
Claisen rearrangement of APE was calculated by a DFT calculation
produces ortho-substituted phenol. The present work will open a
doorway to new non-thermal reactions induced by the molecular
vibrational excitation in the electronic ground state.
**
(
B3LYP/6-311 + G ) to be ꢀ35 kcal/mol, in good agreement with
À1
earlier reports [28,29]. The energy of 5200 cm
is lower than
the activation energy of the classical Claisen rearrangement trig-
gered by the thermal energy. The reason why the reaction proceeds
after the stimulated Raman excitation can be explained by the fol-
lowing two possible mechanisms:
Acknowledgments
The authors are grateful to the Information Technology Center
of the University of Electro-Communications for their support of
the DFT calculations.
(
a) The reaction progresses even with activation energy lower
than the classical Claisen rearrangement for activation of
the vibrational mode that corresponds to the reaction coor-
dinate in the stimulated Raman process. The vibrational
modes of the six-membered structure observed in the spec-
trum (Figure 5) evidence that the reaction follows the
scheme of the classical Claisen rearrangement (Figure 1a).
However, whether or not the detailed reaction pathway to
the six-membered structure is different from that of the
classical Claisen rearrangement is still controversial.
Appendix A. Supplementary data
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