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, with formation 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 to their low stability. The nature of the photoproducts formed by irradiation of CA/aryl alkyl sulfides was independent of solvent properties, even though the reactivity was higher in MeCN than in CH2Cl2.

Photoinduced Hydrogen- and Electron- Transfer Processes Between Chloranil and Aryl Alkyl Sulfides in Organic Solvents. Steady-state and Time-resolved Studies / DEL GIACCO, T.; Elisei, F.; Lanzalunga, Osvaldo. - In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS. - ISSN 1463-9076. - 2:(2000), pp. 1701-1708. [10.1039/a909372i]

Photoinduced Hydrogen- and Electron- Transfer Processes Between Chloranil and Aryl Alkyl Sulfides in Organic Solvents. Steady-state and Time-resolved Studies

LANZALUNGA, Osvaldo
2000

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, with formation 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 to their low stability. The nature of the photoproducts formed by irradiation of CA/aryl alkyl sulfides was independent of solvent properties, even though the reactivity was higher in MeCN than in CH2Cl2.
2000
SULFIDES; PHOTOINDUCED ELECTRON TRANSFER
01 Pubblicazione su rivista::01a Articolo in rivista
Photoinduced Hydrogen- and Electron- Transfer Processes Between Chloranil and Aryl Alkyl Sulfides in Organic Solvents. Steady-state and Time-resolved Studies / DEL GIACCO, T.; Elisei, F.; Lanzalunga, Osvaldo. - In: PHYSICAL CHEMISTRY CHEMICAL PHYSICS. - ISSN 1463-9076. - 2:(2000), pp. 1701-1708. [10.1039/a909372i]
File allegati a questo prodotto
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/47239
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 22
  • ???jsp.display-item.citation.isi??? 20
social impact