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Titolo:
Stability and reactivity of electrogenerated cobalt(I) towards aryl halides in the presence of additives such as vinyl acetate or methyl vinyl ketone- Application to the electrosynthesis of arylzinc compounds
Autore:
Buriez, O; Nedelec, JY; Perichon, J;
Indirizzi:
CNRS, UMR 7582, Lab Electrochim Catalyse & Synth Organ, F-94320 Thiais, France CNRS Thiais France F-94320 atalyse & Synth Organ, F-94320 Thiais, France
Titolo Testata:
JOURNAL OF ELECTROANALYTICAL CHEMISTRY
fascicolo: 2, volume: 506, anno: 2001,
pagine: 162 - 169
Fonte:
ISI
Lingua:
ENG
Soggetto:
CATALYTIC REDUCTION; CYCLIC VOLTAMMETRY; SALEN;
Keywords:
electrosynthesis; cobalt; oxidative addition; kinetics; vinyl acetate; arylzinc compounds;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
21
Recensione:
Indirizzi per estratti:
Indirizzo: Buriez, O CNRS, UMR 7582, Lab Electrochim Catalyse & Synth Organ, 2 Rue H Dunant, F-94320 Thiais, France CNRS 2 Rue H Dunant Thiais France F-94320 -94320 Thiais, France
Citazione:
O. Buriez et al., "Stability and reactivity of electrogenerated cobalt(I) towards aryl halides in the presence of additives such as vinyl acetate or methyl vinyl ketone- Application to the electrosynthesis of arylzinc compounds", J ELEC CHEM, 506(2), 2001, pp. 162-169

Abstract

The electrochemical reduction of CoBr2 in acetonitrile + pyridine (v/v = 9:1) has been investigated. In this solvent mixture, the disproportionation reaction rate of the electrogenerated Co(I) is about twice as slow as in dimethylformamide + pyridine (9:1) and the reaction between Co(I) and arylhalides, ArX, also is slowed down by the same factor. We show that the use of vinyl acetate (vinyl-OAc) or methyl vinyl ketone (MVK) as additives in acetonitrile + pyridine increases the stability of Co(I). Thus, in the presenceof vinyl-OAc the disproportionation reaction rate of Co(I) is divided by seven whereas the rate of the oxidative addition of Co(I) with aryl halides is divided only by two. Preparative-scale electrolyses of arylzine compounds confirm this result since the quantity of catalyst, CoBr2, can be dividedby four as compared to the amount used in the absence of additives. In thetwo cases (presence of vinyl-OAc or MVK) the presence of pyridine is required to stabilize Co(I). In these reactions, the rate constants for both chemical reactions (disproportionation reaction and oxidative addition) have been determined and the stabilization of Co(I) is discussed in terms of formation of pi -complexes with the additives. (C) 2001 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 21/09/20 alle ore 12:35:01