258 research outputs found
Heterogenisation of ketone catalysts within mesoporous supports for asymmetric epoxidation
The synthesis of the first mesoporous silica (150 Ã…) anchored carbohydrate-derived chiral ketone is described. This new heterogeneous catalyst has been shown to be effective in the asymmetric epoxidation of olefins by oxone. The heterogeneous ketone catalyst has comparable activity to that of its homogeneous counterpart and returned enantioselectivities up to 90% e.e
Recombination of Geminate (OH,eaq-) Pairs in Concentrated Alkaline Solutions: Lack of Evidence For Hydroxyl Radical Deprotonation
Picosecond dynamics of hydrated electrons and hydroxyl radicals generated in
200 nm photodissociation of aqueous hydroxide and 400 nm (3-photon) ionization
of water in concentrated alkaline solutions were obtained. No deprotonation of
hydroxyl radicals was observed on sub-nanosecond time scale, even in 1-10 M KOH
solutions. This result is completely at odds with the kinetic data for
deprotonation of OH radical in dilute alkaline solutions. We suggest that the
deprotonation of hydroxyl radical is slowed down dramatically in concentrated
alkaline solutions.Comment: 12 pages; 2 figures; submitted to Chem. Phys. Let
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