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Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. October 2005, Volume 4, Number 10, 698-710 |
Ab initio Computations for the Ring-Opening Potential of Propylene Oxide:
Roles of a Proton and a Water Molecule
Hiroyuki Shinoda, Michio Sayama, Yoshihiro Mori, and Mineyuki Mizuguchi
Internet Electron. J. Mol. Des. 2005, 4, 698-710
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Abstract:
Ab initio computations for the ring-opening potential of propylene
oxide were carried out. The MP2/6-31G**, MP2/6-31++G**, MP3/6-31G**,
MP3/6-31++G**, and QCISD/6-31G** calculations were used
to obtain the most stable structure of propylene oxide. MP2/6-31G**
calculations were performed for the C-O bond stretching of propylene
oxide in five systems: an isolated propylene oxide, a hydrated
propylene oxide, a protonated propylene oxide, a protonated and
hydrated propylene oxide, and a propylene oxide with a hydronium
ion. The aim of these calculations was to reveal what conditions allow
spontaneous completion of the ring-opening process of propylene
oxide to create a propanal. Two conclusions can be drawn from our
results. The first is that the ring-opening process never proceeds
spontaneously under the conditions considered in this study. The
second conclusion, drawn from the IRC calculations, is that both the
ring-opening process and the hydrogen transfer process occur in a one-step
reaction and that the reaction paths are slightly affected by the
level of basis set and electronic correlation used in the calculation. The
results of the localized molecular orbitals calculations reveal that the
low valence of the carbon atom of a breaking C-O bond hinders the C-O bond breaking.
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