92967-24-3Relevant articles and documents
Sructure an Mechanism in the Photo-Retro-Aldol Type Reactions of Nitrobenzyl Derivatives. Photochemical Heterolytic Cleavage of C-C Bonds
Wan, Peter,Muralidharan, S.
, p. 4336 - 4345 (2007/10/02)
The photo-retro-aldol type reactions of several nitroaromatic compounds have been studied in aqueous solution over the pH 1-14 range.These reactions are observed only in aqueous or in predominantly aqueous solution.Catalysis of reaction due to hydroxide ion is observed for several derivatives.Quantum yields of reaction and product ratios (of nitrotoluene vs dinitrobibenzyl) are reported as a function of pH.The proposed mechanism of reaction involves heterolytic cleavage of the benzylic C-C bond from the triplet excited state in the primary photochemical step to generate a nitrobenzyl carbanion and a carbocation-equivalent fragment, except for the nitrophenylacetates 24-26, which eliminate CO2 in place of such a fragment.Photogenerated nitrobenzyl carbanions are efficiently trapped by molecular oxygen to give isolable hydroperoxides at pH 9 M-1 s-1.The results show that photochemical C-C bond heterolysis requires favorable stabilization of both the carbanion and carbocation-derived fragments.Hydroxide ion catalysis may also facilitate the process.The use of the nitrobenzyl moiety as the carbanion-stabilizing group appears to be generally applicable, as demonstrated by the systems studied.
Electron Apportionment in Cleavage of Radical Anions. 1. Nitro-Substituted Benzyl Phenyl Ethers
Maslak, Przemyslaw,Guthrie, Robert D.
, p. 2628 - 2636 (2007/10/02)
The radical anions of 4-nitrobenzyl phenyl ethers undergo cleavage at least 10E4 times faster than the radical anions of corresponding 4-nitrophenyl benzyl ethers despite a perceived thermodynamic advantage for the latter set of reactions.It is suggested that this results reflects a kinetic advantage for cleavage reactions which take place with regioconservation of spin density.
Base Catalysed Rearrangements involving Ylide Intermediates. Part 15. The Machanism of the Stevens Rearrangement
Ollis, W. David,Rey, Max,Sutherland, Ian O.
, p. 1009 - 1027 (2007/10/02)
The Stevens rearrangement of acyl-stabilised ammonium ylides has been investigated with regard to stereoselectivity, intramolecularity and the formation of products in addition to the rearrangement product.A detailed study of the effects of reaction conditions upon the rearrangement of the ylide derived from the salt (13) has shown that the stereoselectivity (retention of the configuration of the chiral migrating group) and intramolecularity decrease as solvent viscosity decreases.The rearrangement of the salt (13) in water at 0 deg C is essentially intramolecular with virtually complete retention of the configuration of the migrating group.These results, together with the isolation of products that can be rationalised on the basis of random free-radical coupling, indicate that the rearrangement of acyl-stabilised ammonium ylides normally involves a radical pair mechanism.