The Photochemistry of Sulfoxides and Related Compounds

Jenks, William S.; Gregory, Daniel D.; Guo, Yushen; Lee, Woo‐Jae; Tetzlaff, T.

doi:10.1201/b16837-1

Cited by 18 publications

(29 citation statements)

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“…The photolysis of sulfur-containing compounds is another source of free radicals. , Photolysis of diphenyl disulfide leads to two molecules of PhS • . Similarly, excitation of sulfides 5 and 6 leads to the production of sulfenyl (thiyl) radicals and carbon-centered radicals • CHPh 2 and • CPh 3 with absorption maxima at 331 and 338 nm, respectively. , …”

Section: Resultsmentioning

confidence: 99%

“…These observations led us to believe that the peroxyl radical might be an efficient quencher of singlet oxygen regardless of substituent and to pursue the experiments described herein. Additionally, our recent interest in sulfoxide photochemistry has brought us experience with sulfinyl radicals (RSO • ), whose relationship to peroxyl radicals is obvious. Much less is known about these species in general, but no excited state lying below 8000 cm -1 is known for HSO • , which implied that there might be decidedly contrasting behavior between the peroxyl and sulfinyl species toward singlet oxygen.…”

Section: Introductionmentioning

confidence: 99%

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Quenching of Singlet Oxygen by Oxygen- and Sulfur-Centered Radicals: Evidence for Energy Transfer to Peroxyl Radicals in Solution

et al. 1998

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Quenching of singlet oxygen luminescence at 1.27 µm by PhS • , PhSO • , and peroxyl radicals PhOO • , t-BuOO • , PhCH 2 OO • , Ph 2 CHOO • , and Ph 3 COO • was studied in liquid solution. The quantum yields of decomposition of different initiators which lead to the formation of free radicals were measured by using nanosecond transient absorption. This allowed determination of singlet oxygen O 2 ( 1 ∆ g ) quenching rate constants by the radicals. They are <2 × 10 8 M -1 s -1 for the sulfur-centered radicals and (2-7) × 10 9 M -1 s -1 for peroxyl radicals in acetonitrile. The rapid quenching is attributed to energy transfer quenching by the peroxyls, which have an n f π* transition leading to a low-lying 2 A′ state above their 2 A′′ ground state. PhSO • is shown computationally not to have such a low-lying 2 A′ state. There may be a very low-lying 2 B 1 state, for PhS • , but it is apparently not an efficient acceptor of electronic energy from O 2 ( 1 ∆ g ).

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quenching of Singlet Oxygen by Oxygen- and Sulfur-Centered Radicals: Evidence for Energy Transfer to Peroxyl Radicals in Solution

et al. 1998

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“…One of the common mechanistic assumptions in sulfoxide photochemistry is that the primary step after excitation is homolytic α-cleavage of one of the C−S bonds to form a radical pair or biradical. − Recently we have carefully examined a series of aryl alkyl sulfoxides by steady state photolysis techniques and found that nearly all of the observed chemistry could be accounted for by α-cleavage to form a carbon centered radical and arylsulfinyl radical. Cleavage is followed by competition between diffusional separation of the radical pair to form free radicals, recombination to form sulfoxide, and recombination to form sulfenic ester (Scheme ) …”

Section: Introductionmentioning

confidence: 99%

Generation and Decay of Aryl Sulfinyl and Sulfenyl Radicals: A Transient Absorption and Computational Study

et al. 1997

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Absorption spectra and extinction coefficients of phenylsulfinyl and phenylsulfenyl (thiyl) radicals are determined by nanosecond laser photolysis in various solvents. Direct observation and characterization of arylsulfinyl radicals from the photolysis of several aromatic sulfoxides provides the strongest evidence to date for R-cleavage as the predominant primary photochemical process for these compounds. The absorption spectrum of phenylsulfinyl, with λ max ) 300 and 450 nm and ) 1.1 × 10 4 and 1.3 × 10 3 M -1 cm -1 , is practically independent of solvent. Quantum yields of free sulfinyl radicals range from 0.09 to 0.18 in various solvents. Recombination rate constants very near diffusion control indicate that there is a large spin-orbital coupling in the radical pair. Rate constants for the reactions of arylsulfinyl radicals with stable nitroxide radicals are among the fastest known, but reactivity with O 2 is very modest. Computations indicate that the singly occupied molecular orbital is a π* orbital largely localized on the sulfur and oxygen atoms.

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“…This type of reaction has precedents in the literature, but the mechanism has yet to be elucidated . Upon photolysis, aryl benzyl sulfoxides are proposed to undergo α-cleavage to form a radical pair which upon recombination in the solvent cage yields the corresponding sulfenate as the first step in the rearrangement reaction 5b…”

Section: Introductionmentioning

confidence: 99%