ChemInform Abstract: ENOLS BY THE NORRISH TYPE-II CLEAVAGE OF CARBONYL COMPOUNDS IN SOLUTION

1976 ◽  
Vol 7 (40) ◽  
pp. no-no
Author(s):  
ANDREAS HENNE ◽  
HANNS FISCHER
2020 ◽  
Vol 74 (1) ◽  
pp. 39-48 ◽  
Author(s):  
Andreas Herrmann

Photoirradiation of 2-oxoacetates (α-ketoesters) with UV-A light proceeds via an intramolecular hydrogen abstraction of the triplet state in a Norrish type II pathway to form carbonyl compounds, carbon monoxide and/or dioxide, and a series of other side products. This review gives a detailed overview of the mechanistic aspects of photooxidation by explaining the pathways that yield the major products formed in the presence or absence of oxygen. Furthermore, it demonstrates how the photoreaction can be used for the light-induced controlled release of fragrances from non-polymeric profragrances, polymer conjugates and core-shell microcapsules in applications of functional perfumery. In the case of microcapsules, the gas formation accompanying the Norrish type II fragmentation can generate an overpressure that expands or cleaves the capsule wall to release fragrances and thus provides access to multi-stimuli responsive delivery systems.


1999 ◽  
Vol 64 (12) ◽  
pp. 2007-2018 ◽  
Author(s):  
Petr Klán ◽  
Jaromír Literák

Temperature dependent solvent effects have been investigated on the Norrish Type II reaction of 1-phenylpentan-1-one and its p-methyl derivative. Efficiencies of the photoreaction were studied in terms of solvent polarity and base addition as a function of temperature. Such a small structure change as the p-methyl substitution in 1-phenylpentan-1-one altered the temperature dependent photoreactivity in presence of weak bases. The experimental results suggest that the hydrogen bonding between the Type II biradical intermediate OH group and the solvent is weaker for 1-(4-methylphenyl)pentan-1-one than that for 1-phenylpentan-1-one at 20 °C but the interactions probably vanish in both cases at 80 °C.


1981 ◽  
Vol 103 (13) ◽  
pp. 3837-3841 ◽  
Author(s):  
Peter J. Wagner ◽  
Kou-Chang Liu ◽  
Y. Noguchi
Keyword(s):  
Type Ii ◽  

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