Bromation régiosélective en série aromatique. II. Approche théorique du mécanisme de la substitution électrophile par l'ion tribromure Br3−

Autor:	Jacques Berthelot, Jean-Jacques Basselier, P.L. Desbene, Catherine Guette, Patrick Chaquin, Daniel Masure
Rok vydání:	1990
Předmět:	Stereochemistry Organic Chemistry Halogenation Regioselectivity MNDO General Chemistry Electrophilic aromatic substitution Medicinal chemistry Catalysis chemistry.chemical_compound Electrophilic substitution chemistry Electrophile Selectivity Tribromide
Zdroj:	Canadian Journal of Chemistry. 68:464-470
ISSN:	1480-3291 0008-4042
DOI:	10.1139/v90-070
Popis:	A theoretical study (SCF PS-HONDO + CI) of the stability of the tribromide anion Br3− has been carried out. On the basis of qualitative MO arguments and MNDO calculations, we propose a first approach to the mechanism of electrophilic aromatic substitution by Br3−. It involves an axial attack of linear Br3−, the most electrophilic sites of which are terminal bromine atoms, although they bear a negative charge. This model suggests some arguments to explain the para versus ortho selectivity experimentally observed. Calculations performed on a series of MBr3 systems emphasize the importance of the countercation for the rate of the reaction as well as for its selectivity. Keywords: bromination, tribromide, mechanism, parabromophenol.
Databáze:	OpenAIRE
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