Primary quantum yields of ketyl radicals in photoreduction by amines. Abstraction of hydrogen from nitrogen

Inbar, Shai; Linschitz, Henry; Cohen, Saul G.

doi:10.1021/ja00524a034

Cited by 64 publications

(24 citation statements)

References 8 publications

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“…In the particular case of 1, with ( E~/ E~)~~~ -0.37 as mentioned before, r is estimated to be a result which supports an essentially quantitative chemical quenching (27).…”

Section: Interaction Of 1 and 2 With Triethanolaminesupporting

confidence: 64%

New functionalized water-soluble benzophenones: a laser flash photolysis study

Lougnot¹,

Jacques²,

Fouassier³

et al. 1985

Can. J. Chem.

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Two water-soluble ionic benzophenones containing a quatemized amine and a sulphonate group have been investigated by laser flash photolysis. The decay kinetics and spectra of their triplet states were studied and quenching constants by triethanolamine, isopropanol, and methyl viologen determined. These data are of interest when these benzophenones are used as initiators for photo-polymerizing water-soluble acrylates in homogeneous solution or in reverse micellar assemblies. The high water solubility of these compounds allows the bimolecular deactivations due to triplet–triplet (kTT) and triplet–ground state (kSQ) interactions to be determined more accurately than in the case of benzophenone itself.

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“…In the particular case of 1, with ( E~/ E~)~~~ -0.37 as mentioned before, r is estimated to be a result which supports an essentially quantitative chemical quenching (27).…”

Section: Interaction Of 1 and 2 With Triethanolaminesupporting

confidence: 64%

New functionalized water-soluble benzophenones: a laser flash photolysis study

Lougnot¹,

Jacques²,

Fouassier³

et al. 1985

Can. J. Chem.

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“…The ratio of optical density after and before triplet decay is a measure of the yield of ketyl radical. Using triethylamine as an actinometer (18), it can be estimated that at least 80% of the quenching takes place via formation of ketyl radicals (i.e. by Habstraction from the amine), reactions [6] and [7].…”

Section: Quenching Of Benzophenone Tripletsmentioning

confidence: 99%

Transient spectroscopy and kinetics of the reactions of mesocyclic diamines with tert-butoxyl and with ketone triplets. Effects of ring conformation

Scaiano¹,

Stewart²,

Livant³

et al. 1984

Can. J. Chem.

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Absolute rate constants for the reactions of terr-butoxyl and triplet benzophenone, with a series of di-tert-amines have been obtained via laser flash photolysis. These diamines have in common the feature that the nitrogen centers are in the backbone of an aliphatic eight-membered ring at positions 1 and 5. A modest rate enhancement is observed, particularly for 1 in its H-abstraction reaction with tert-butoxyl, which may be explained by the operation of a stereoelectronic effect. From thc absorption maxima of the radical cations of these diamines (produced quenching acetophenone triplets), information concerning the conformations of the eight-membered rings may be inferred. It is concluded that these radical-cations are stabilized by relatively strong through-space bonding interactions between the two nitrogen centers. IntroductionThe study of medium-ring (so-called mesocyclic) systems has provided chemists with a number of surprising results. In particular, heteroatom-substituted eight-membered rings are peculiar. 1,s-Dithiacyclooctane shows appreciable S-S interaction as evidenced by a splitting of 0.43 eV in its photoelectron (PE) spectrum (1). 1,4-Dithiacycloheptane, 13-dithiacyclononane, and 1,6-dithiacyclodecane each shows negligible S-S interaction (

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“…Reduction of the excited state of a ketone by an amine leads to radical formation, which initiates polymer chain reaction. The photoreduction of benzophenone in the presence of amines has been intensively investigated by Cohen [11,12] and Peters. [13] The benzophenone-derivative triplet state is photoreduced by amines via the photoinduced intermolecular electron transfer mechanism (PET), which is followed by transformations yielding free radicals able to initiate polymerization.…”

Section: Introductionmentioning

confidence: 99%

Tetraalkylammonium Salts of Amino Acids and Sulfur‐Containing Amino Acids as Effective Co‐Initiators of Free Radical Polymerization in the Presence of Aromatic Ketones

Ścigalski

Pączkowski

2008

Macro Chemistry & Physics

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Photoredox pairs, composed of xanthone or thioxanthone derivatives acting as light absorbers and tetrabutylammonium salts of amino acids or sulfur-containing amino acids as co-initiators, were studied as photoinitiators for free-radical polymerization. The mechanism of free-radical formation was established using the laser flash photolysis. Measurements of polymerization kinetics show that the photoinitiation ability of the xanthone-or thioxanthone-derivative/ amino acid or sulfur-containing amino acid pairs depends on the initiator and co-initiator properties, mostly on the triplet state lifetime of xanthone or thioxanthone derivatives.

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Primary quantum yields of ketyl radicals in photoreduction by amines. Abstraction of hydrogen from nitrogen

Cited by 64 publications

References 8 publications

New functionalized water-soluble benzophenones: a laser flash photolysis study

New functionalized water-soluble benzophenones: a laser flash photolysis study

Transient spectroscopy and kinetics of the reactions of mesocyclic diamines with tert-butoxyl and with ketone triplets. Effects of ring conformation

Tetraalkylammonium Salts of Amino Acids and Sulfur‐Containing Amino Acids as Effective Co‐Initiators of Free Radical Polymerization in the Presence of Aromatic Ketones

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