PHOTOCHEMICAL C-S BOND CLEAVAGE IN METHYL ARYL SULFIDES AND SULFOXIDES. A CIDNP STUDY OF REACTIVITY ENHANCEMENT BY METHYLTHIO GROUPS.<sup>1</sup>

Lüdersdorf, Reinhard; Khait, Igor; Muszkat, K. A.; Praefcke, Klaüs; Margaretha, P.

doi:10.1080/03086648108078288

Cited by 10 publications

(11 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Photochemical Processes . The photochemistry of DBTO in various liquids has been studied for more than 25 years. − Most recently, Jenks and co-workers have performed several extensive mechanistic investigations of the processes involved . Irradiation of a DBTO molecule leads to efficient dissociation of the S−O bond, producing DBT and a ground-state oxygen atom ( 3 O P ) that is able to oxidize a wide range of solvents.…”

Section: Resultsmentioning

confidence: 99%

Method for Hydroxylation and Esterification of Interior Sites of Polyolefinic Films

Wang

Weiss

1999

Macromolecules

View full text Add to dashboard Cite

A method is described to functionalize specifically the interior portions of polyolefinic films with chromophoric/lumophoric groups. In the first step, a film doped with dibenzothiophene 5-oxide (DBTO) is irradiated (λ > 300 nm) to produce O(3P) atoms that oxidize nearby C−H bonds of the polymer. Covalent attachment of acid chlorides (containing chromophoric/lumophoric groups) to the hydroxy bonds (via ester linkages) provides films that retain their absorption and luminescence in water or air for long periods. The esterified films have been characterized using UV/vis absorption spectroscopy and static and dynamic fluorescence techniques. Fluorescence from native or modified and then esterified films in 1.0 M methanolic 2-(dimethylamino)ethanol, a surface quencher, indicates that the vast majority of the chromophores/lumophores are located inside the films. Selective modification of the film surfaces by an analogous method was not efficient. However, a very low concentration of hydroxy groups is present throughout the native films. Their esterification reduces the fluorescence contrast between undoped/irradiated and DBTO-doped/irradiated parts of a film.

show abstract

Section: Resultsmentioning

confidence: 99%

Method for Hydroxylation and Esterification of Interior Sites of Polyolefinic Films

Wang

Weiss

1999

Macromolecules

View full text Add to dashboard Cite

show abstract

“…Some physical evidence for sulfoxide α-cleavage in solution (beyond conclusions drawn from product study) was previously available. This took the form of weak EPR signals of sulfinyl radicals at low temperature − and chemically induced dynamic nuclear polarization (CIDNP) signals attributed to the intermediacy of sulfinyls. − However, overinterpretation of such data without corroborating evidence can be misleading as they do not necessarily indicate radical pathways for the majority of material. Only a brief and qualitative report of a transient absorption spectrum attributed to phenylsulfinyl has appeared previously .…”

Section: Introductionmentioning

confidence: 99%

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

et al. 1997

View full text Add to dashboard Cite

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.

show abstract

“…3 A second mechanistic proposal involved oxygen atom transfer from the sulfinyl radical formed after S-C cleavage, but this is now known to be energetically unfeasible. 7,[13][14][15] A unimolecular dissociation mechanism resulting in the direct formation of atomic oxygen O( 3 P) is now supported by several lines of evidence. [6][7][8][9][10][11][12] (1) Deoxygenation of DBTO persists at 77 K in organic glass matrices; (2) the quantum yield is independent of sulfoxide concentration; (3) photolysis of DBTO in the presence of excess Ph 2 SO does not produce Ph 2 S; (4) the quantum yield is not solvent-sensitive in a manner consistent with a hydrogen abstraction mechanism; (5) solvents are oxidized in a manner consistent with the production of O( 3 P).…”

Section: Introductionmentioning

confidence: 87%

Computational investigation of the photochemical deoxygenation of thiophene- S-oxide and selenophene- Se-oxide

Stoffregen

Lee

Dickerson

et al. 2014

Photochem Photobiol Sci

View full text Add to dashboard Cite

CASSCF and multireference MP2 calculations were carried out on thiophene-S-oxide (TO) and selenophene-Se-oxide (SeO), comparing the energies of the ground state to the first two electronically excited singlet and triplet states, using constrained optimizations and multiple fixed S-O or Se-O distances. For both molecules, one of the two triplet states smoothly dissociates to yield O((3)P) with little or no barrier. Single point calculations are consistent with the same phenomenon occurring for dibenzothiophene-S-oxide (DBTO). This provides an explanation for the inefficient unimolecular photochemical dissociation of O((3)P) from DBTO despite a phosphorescence energy below that of S-O dissociation, i.e., that S-O scission probably occurs from a spectroscopically unobserved triplet (T2) state.

show abstract

PHOTOCHEMICAL C-S BOND CLEAVAGE IN METHYL ARYL SULFIDES AND SULFOXIDES. A CIDNP STUDY OF REACTIVITY ENHANCEMENT BY METHYLTHIO GROUPS.¹

Cited by 10 publications

References 20 publications

Method for Hydroxylation and Esterification of Interior Sites of Polyolefinic Films

Method for Hydroxylation and Esterification of Interior Sites of Polyolefinic Films

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

Computational investigation of the photochemical deoxygenation of thiophene- S-oxide and selenophene- Se-oxide

Contact Info

Product

Resources

About

PHOTOCHEMICAL C-S BOND CLEAVAGE IN METHYL ARYL SULFIDES AND SULFOXIDES. A CIDNP STUDY OF REACTIVITY ENHANCEMENT BY METHYLTHIO GROUPS.1

Cited by 10 publications

References 20 publications

Method for Hydroxylation and Esterification of Interior Sites of Polyolefinic Films

Method for Hydroxylation and Esterification of Interior Sites of Polyolefinic Films

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

Computational investigation of the photochemical deoxygenation of thiophene- S-oxide and selenophene- Se-oxide

Contact Info

Product

Resources

About

PHOTOCHEMICAL C-S BOND CLEAVAGE IN METHYL ARYL SULFIDES AND SULFOXIDES. A CIDNP STUDY OF REACTIVITY ENHANCEMENT BY METHYLTHIO GROUPS.¹