151390-61-3Relevant articles and documents
Diffusion and percolation of radical pairs in zeolite media. A product analysis study
Garcia-Garibay, Miguel A.,Zhang, Zhenyu,Turro, Nicholas J.
, p. 6212 - 6218 (1991)
The photochemistry of dibenzyl-d5 ketone (DBK-d5) adsorbed in the zeolite NaX was investigated as a function of substrate loading. The cage effect and the relative yields of 1,2-diphenylethane (DPE), o-methyl-β-phenylacetophenone (o-MAP), and p-methyl-β-phenylacetophenone (p-MAP) were found to depend dramatically on the loading of the starting material present. These results and the variations observed in the percent cage effect are described in terms of local and global effects that determine the influence of the zeolite media. Changes in reactivity as a function of reactant loading are explained in terms of percolation theory by using the model "ants in a labyrinth" proposed by de Gennes. The diffusing radicals play the role of the ants and the disposition of the reactant in the regular zeolite topology determines the nature of the labyrinth. This model implies that the diffusion coefficient of the radicals is larger than the diffusion coefficient of the starting ketone. The model is supported by trapping experiments with an oxygen scavenger and by experiments carried out at -20 °C where the diffusion of the radicals is largely diminished.
Palladium-catalyzed hydrogenation: Detection of palladium hydrides. A joint study using para-hydrogen-enhanced NMR spectroscopy and density functional theory
Lopez-Serrano, Joaquin,Duckett, Simon B.,Lledos, Agusti
, p. 9596 - 9597 (2007/10/03)
Pd(PEt3)2(OTf)2, acting as an in situ source of Pd(PEt3)2, reacts with an alkyne and hydrogen via phosphine loss to form the detectable hydride-containing species Pd(PEt3)2(H)(CHPhCH2Ph), cis- and trans-Pd(PEt3)2(H)(CPh=CHPh), and Pd2(PEt3)3(H)(CHPhCH2Ph)2+, which map onto the reaction scheme predicted by density functional theory. Copyright
Micellar Systems as ''Supercages'' for Reactions of Geminate Radical Pairs. Magnetic Effects
Turro, Nicholas J.,Weed, Gregory C.
, p. 1861 - 1868 (2007/10/02)
The photochemistry of dibenzyl ketone (DBK) and other molecules capable of producing benzyl radicals and substituted benzyl radicals has been investigated in micellar systems.The cage effect (percent of unscavengeable radical pairs produced by photolysis) was measured under a variety of conditions, and the results are compared with those obtained in homogeneous organic solvents.For example, parameters such as mean occupancy of ketone, detergent type and concentration, O2 concentration, additives, temperature, applied magnetic field, and pressure have been varied and investigated as to their influence on the magnitude of cage effect.In addition to modifying its environment, structural modification of the DBK by incorporation of 2H and 13C isotopes, hydrophobic groups, and heavy atoms was performed to investigate the impact of these variations on the cage effect in micellar systems.Isotopic substitution of 2H or 13C leads to results on both the quantum yields for reactions and on the percent cage that were consistent with expectations of magnetic isotope effects.Hydrophobic groups substituted in the 4-position of DBK were found to cause a substantial increase in the cage effect and yet retain the magnetic-field-dependent character found in the parent DBK.Incorporation of Br in the 4-position of DBK was found to enhance the cage effect but at the same time cause the cage effect to become magnetic field independent.Substitution of α-naphthyl for phenyl in DBK also produced magnetic-field-independent behavior, in addition to a dramatic decrease in the efficiency of photolysis.
