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Titolo:
Photoinduced hydrogen- and electron-transfer processes between chloranil and aryl alkyl sulfides in organic solvents. Steady-state and time-resolved studies
Autore:
Del Giacco, T; Elisei, F; Lanzalunga, O;
Indirizzi:
Univ Perugia, Dipartimento Chim, I-06123 Perugia, Italy Univ Perugia Perugia Italy I-06123 rtimento Chim, I-06123 Perugia, Italy Univ La Sapienza, CNR, Ctr Studio Meccanismi Reaz, I-00185 Rome, Italy Univ La Sapienza Rome Italy I-00185 Meccanismi Reaz, I-00185 Rome, Italy Univ La Sapienza, Dipartimento Chim, I-00185 Rome, Italy Univ La SapienzaRome Italy I-00185 partimento Chim, I-00185 Rome, Italy
Titolo Testata:
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
fascicolo: 8, volume: 2, anno: 2000,
pagine: 1701 - 1708
SICI:
1463-9076(2000)2:8<1701:PHAEPB>2.0.ZU;2-9
Fonte:
ISI
Lingua:
ENG
Soggetto:
TRIPLET EXCITED COMPLEXES; RADICAL ION-PAIRS; CONTAINING MONOOXYGENASE; ENZYMATIC OXIDATION; PROTON-TRANSFER; S-OXYGENATION; CYTOCHROME-P-450; CATIONS; MECHANISM; SYSTEM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
46
Recensione:
Indirizzi per estratti:
Indirizzo: Del Giacco, T Univ Perugia, Dipartimento Chim, Via Elce di Sotto 8, I-06123 Perugia, Italy Univ Perugia Via Elce di Sotto 8 Perugia Italy I-06123 taly
Citazione:
T. Del Giacco et al., "Photoinduced hydrogen- and electron-transfer processes between chloranil and aryl alkyl sulfides in organic solvents. Steady-state and time-resolved studies", PHYS CHEM P, 2(8), 2000, pp. 1701-1708

Abstract

The photochemical behavior of three aryl alkyl sulfides, thioanisole (TA),benzyl phenyl sulfide (BPS) and 4-methoxybenzyl phenyl sulfide (MBPS), sensitized by triplet chloranil (CA), was investigated by nanosecond laser flash photolysis and steady-state irradiation in CH2Cl2 and MeCN. The nature of the transients detected upon 355-nm laser excitation was independent of the molecular structure of the aryl alkyl sulfides but strongly affected by the solvent polarity. In particular, in CH2Cl2 the quenching process of triplet CA by aryl alkyl sulfides was accompanied by H-transfer, with formation of the CAH(.) and TA(-H)(.)/BPS(-H)(.)/MBPS(-H)(.) radicals. In contrast,a charge transfer process between triplet CA and aryl alkyl sulfides, withformation of the radical anion CA(.-) and radical cations of aryl alkyl sulfides, occurred in MeCN. In this solvent, a transient detected at long delay time was tentatively assigned to the anion CAH(-) formed by H-transfer between radical ions. In all experiments, transient species were characterized in terms of second-order decay rate constants and quantum yields of formation. Steady-state irradiation of the CA/TA system led to the stable photoadduct C6H5SCH2OC6Cl4OH in both CH2Cl2 and MeCN with quantum yields of 0.033 and 0.27, respectively. In contrast, aldehydes, thioacetals, and disulfides were the main products obtained upon irradiation of the CA/BPS and CA/MBPS systems. The photoaddition products were not observed, probably owing totheir low stability. The nature of the photoproducts formed by irradiationof CA/aryl alkyl sulfides was independent of solvent properties, even though the reactivity was higher in MeCN than in CH2Cl2.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 16:03:52