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Titolo:
LINEAR FREE-ENERGY RELATIONSHIPS IN THE KINETIC-STUDY OF OXIDATION OFPHENOLS BY QUINOLINIUM DICHROMATE
Autore:
ARUNA K; MANIKYAMBA P;
Indirizzi:
KAKATIYA UNIV,DEPT CHEM WARANGAL 506009 ANDHRA PRADESH INDIA KAKATIYA UNIV,DEPT CHEM WARANGAL 506009 ANDHRA PRADESH INDIA
Titolo Testata:
International journal of chemical kinetics
fascicolo: 6, volume: 29, anno: 1997,
pagine: 437 - 443
SICI:
0538-8066(1997)29:6<437:LFRITK>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
PRIMARY ALIPHATIC-ALCOHOLS; PYRIDINIUM FLUOROCHROMATE; CHLOROCHROMATE; MECHANISM; SULFIDES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
32
Recensione:
Indirizzi per estratti:
Citazione:
K. Aruna e P. Manikyamba, "LINEAR FREE-ENERGY RELATIONSHIPS IN THE KINETIC-STUDY OF OXIDATION OFPHENOLS BY QUINOLINIUM DICHROMATE", International journal of chemical kinetics, 29(6), 1997, pp. 437-443

Abstract

The oxidation of ortho-, meta-, and para-substituted phenols by Quinolinium Dichromate (QDC) to the corresponding Quinones in aqueous acetic acid medium is first-order with respect to [QDC] and [phenol]. Thereis no effect of added Quinoline on rate. The reaction is acid catalysed. A medium of low dielectric constant favors the oxidation process, and the rate of the oxidation process changes with change in the ionicstrength of the medium. Electron releasing groups on the benzene ringenhance the rate of oxidation, while electron withdrawing groups retard, compared to the unsubstituted phenol. A correlation exists betweenlog k(2) and sigma, the Hammett's substituent constant, with a slope of -3.79 at 303 K. Analysis of the rate data using sigma(l) and sigma(R) values indicate that both inductive and resonance effects of the substituents equally influence the rate of the reaction. The free energyof-activation, Delta G(#), is linearly correlated with a. A probable mechanism is proposed. (C) 1997 John Wiley & Sons, Inc.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 17:46:50