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Titolo:
A quantum chemical study of vapor-phase Beckmann rearrangement mechanisms on oxide catalysts
Autore:
Shinohara, Y; Mae, S; Shouro, D; Nakajima, T;
Indirizzi:
Shinshu Univ, Grad Sch Sci & Technol, Div Mat Engn, Nagano 3808553, Japan Shinshu Univ Nagano Japan 3808553 l, Div Mat Engn, Nagano 3808553, Japan
Titolo Testata:
JOURNAL OF MOLECULAR STRUCTURE-THEOCHEM
, volume: 497, anno: 2000,
pagine: 1 - 9
SICI:
0166-1280(20000201)497:<1:AQCSOV>2.0.ZU;2-M
Fonte:
ISI
Lingua:
ENG
Soggetto:
CYCLOHEXANONE OXIME; GAS-PHASE; DECOMPOSITION METHOD; ZEOLITE;
Keywords:
MOPAC; Beckmann rearrangement; cyclohexanone oxime; oxide catalysts; reaction mechanisms;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
26
Recensione:
Indirizzi per estratti:
Indirizzo: Shinohara, Y Shinshu Univ, Grad Sch Sci & Technol, Div Mat Engn, 500 Wakasato, Nagano 3808553, Japan Shinshu Univ 500 Wakasato Nagano Japan 3808553 808553, Japan
Citazione:
Y. Shinohara et al., "A quantum chemical study of vapor-phase Beckmann rearrangement mechanisms on oxide catalysts", J MOL ST-TH, 497, 2000, pp. 1-9

Abstract

The vapor-phase Beckmann rearrangement mechanism of cyclohexanone oxime onoxide catalysts (SiO2-Al2O3 gamma-Al2O3, SiO2 and ZnO) was quantum chemically investigated using MOPAC 93. It was suggested that the rearrangement onthe oxide surfaces proceeds via a fast step where a Bronsted acid site interacting with the nitrogen atom is transferred to the oxygen atom of the oxime. It was also suggested that the reaction then proceeds via a rate-determining step where the hydroxy group is eliminated with simultaneous alkyl group transfer as proposed for the liquid-phase rearrangement. The activation energies of the vapor-phase rearrangement of the oximes on the oxides were calculated on the basis of this suggested mechanism. The order of the activation energies for these oxides was in good agreement with that of the experimentally determined catalytic selectivities of E-caprolactam. This agreement indicates the validity of the mechanism proposed for the liquid-phasereaction by Landis and Venuto for the vapor-phase reaction. The proposal, suggested by Nguyen et al. for the liquid-phase reaction, in that the rate determining step is the transfer of the Bronsted acid, i.e. proton from thenitrogen atom to the oxygen atom of the oxime is invalid on oxide catalysts. (C) 2000 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 18/11/17 alle ore 05:52:28