Mechanistic study of the ring opening reaction of singlet oxirane

Journal Article · Wed Jun 30 04:00:00 EDT 1993 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00066a052· OSTI ID:5620478

Yamaguchi, Yukio; Schaefer, III, H F ^[1]; Alberts, I L ^[2]

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1. Univ. of Georgia, Athens (United States)
2. Univ. of Edinburgh (United Kingdom)

The C-C ring opening reaction of the oxirane molecule on the singlet potential energy surface has been investigated within the context of ab initio electronic structure theory. Self-consistent-field (SCF), two-configuration SCF (TCSCF), and configuration interaction with single and double excitations (CISD) levels of theory are employed in conjunction with two basis sets, double-[zeta] plus polarization (DZP) and triple-[zeta] plus double polarization (TZ2P). For the SCF and TCSCF methods, the TZ2P basis set supplemented with higher angular momentum functions, TZ(2df,-2pd), is also used. Ten stationary points are located on the singlet reaction surface and unambiguously characterized by analyzing the energy second derivatives (Hessian). Three minima are located on the surface corresponding to the closed-shell ring structure (as reactant) and two closed-shell open structures (as products) of C[sub 2] and C[sub s] symmetry. These minima are shown to be connected via four genuine transition states along the corresponding reaction coordinates. Planar open oxirane with C[sub 2v] symmetry (edge-to-edge, E-E isomer) is characterized as neither a minimum nor a transition state but as a higher order stationary point with Hessian index 2. The electrocyclic ring opening of the C-C bond in oxirane is shown to occur preferably through a conrotatory double methylene rotation pathway leading to the C[sub 2] open structure with an activation energy of 52.0 kcal/mol with the zero-point vibrational energy (ZPVE) correction. 57 refs., 7 figs., 3 tabs.

• DOE Contract Number: FG09-87ER13811
• OSTI ID: 5620478
• Journal Information: Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 115:13; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
664100 -- Theory of Electronic Structure of Atoms & Molecules-- (1992-)
664400 -- Experimentally Derived Information on Atomic & Molecular Properties-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
CHEMICAL REACTIONS
DATA
ELECTRONIC STRUCTURE
ENERGY LEVELS
EPOXIDES
EXCITED STATES
EXPERIMENTAL DATA
INFORMATION
ISOMERIZATION
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
THERMODYNAMICS
VIBRATIONAL STATES