Semiempirical and ab initio molecular orbital studies on the mechanism of the acid-catalyzed isomerization benzene oxide yields phenol. 1. Structure of protonated benzene oxide

Journal Article · Thu Oct 18 04:00:00 EDT 1990 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100384a034· OSTI ID:6234968

George, P ^[1]; Bock, C W ^[2]; Glusker, J P ^[3]

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1. Univ. of Pennsylvania, Philadelphia (USA) Fox Chase Cancer Center, Philadelphia, PA (USA)
2. Philadelphia College of Textiles and Science, PA (USA)
3. Fox Chase Cancer Center, Philadelphia, PA (USA)

The relative stabilities of O-protonated benzene oxide and its related carbonium ions were investigated in order to obtain further insight into the mechanism of the acid-catalyzed isomerization benzene oxide {yields} phenol by using AM1 and the 6-31G and 6-31G* basis sets with full geometry optimization, together with single-point energy determinations MP2/6-31G* and MP3/6-31G* at the RHF/6-31G* geometry. At all levels of computation, three carbonium ions, with a p-quinonoid disposition of the formal double bonds - cis, gauche, and trans with respect to the H{hor ellipsis}H internuclear distance in the CHOH group - were found to be almost equal in energy and significantly more stable than O-protonated benzene oxide by 12-14 kcal mol{sup {minus}1}. The bond lengths, and the distribution of total atomic charge calculated by using Mulliken population analysis, indicate extensive electron delocalization in the carbonium ions. Frequency analyses and calculation of the potential energy curve for the rotation of the carbonium ion H-O bond about the C-O bond show that the gauche and trans rotamers are stable intermediates.

• OSTI ID: 6234968
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 94:21; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
AROMATICS
BENZENE
CALCULATION METHODS
CHEMICAL REACTIONS
HYDROCARBONS
HYDROXY COMPOUNDS
ISOMERIZATION
MATHEMATICAL MODELS
MOLECULAR ORBITAL METHOD
MOLECULAR STRUCTURE
ORGANIC COMPOUNDS
PHENOL
PHENOLS