14 research outputs found
Characterization of Water/Sucrose Laurate/n-Propanol/ Allylbenzene Microemulsions
Water/n-propanol/sucrose laurate/allylbenzene
micellar systems were formulated and applied in the
isomerization of allylbenzene in the presence of heterogenized
derivatives of some platinum group catalysts. The
ratio (w/w) of n-propanol/surfactant studied herewith was
2/1. Temperature insensitive microemulsions were found.
The microemulsions were characterized by the volumetric
parameters, density, excess volume, ultrasonic velocity,
and isentropic compressibility. The densities increase with
increases in the water volume fraction. Excess volumes of
the microemulsions decrease for water volume fractions
below 0.2, level off for water volume fractions between 0.2
and 0.6 then increase for water volume fractions above 0.6.
Excess volumes of the studied micellar systems increase
with temperature. Isentropic compressibilities increase
with temperature for water volume fractions below 0.8 and
decrease for water volume fractions above 0.8. Structural
transitions from water-in-oil to bicontinuous to oil-in-water
occur along the microemulsion phase. The particle hydrodynamic
diameter of the oil-in-water microemulsions at the
0.95 water volume fraction was found to decrease with
temperature.We gratefully acknowledge the financial support
of this trilateral study by the Deutsche Forschungsgemeinschaft
(DFG) through grant SCHO687/8-1
Fluorine-Substituted 1,2-Benzanthracene and 3,4-Benzophenanthrene Derivatives and Related Compounds
Regioselective Hydroaminomethylation of Vinylarenes by a Sol鈥揋el Immobilized Rhodium Catalyst
In the course of our studies toward
the development of new heterogeneous
conditions for better controlling regioselectivity in organic reactions,
we investigated the application of sol鈥揼el immobilized organometallic
catalyst for regioselective hydroaminomethylation of vinylarenes with
aniline or nitroarene derivatives in an aqueous microemulsion. By
immobilization of 6 mol % [Rh颅(cod)颅Cl]<sub>2</sub> within a hydrophobic
silica sol鈥揼el matrix we were able to perform efficient hydroaminomethylation
under mild conditions and isolate 2-arylpropylamines with high regioselectivity.
The regioselectivity of the reaction was found to be mainly dependent
on the hydrophobicity of the catalyst support. It is also significantly
affected by the electronic nature of the substrates, by the reaction
temperature, and by syngas pressure. The heterogenized catalyst can
be reused for several times
One-Pot Sequences of Reactions with Sol-Gel Entrapped Opposing Reagents:聽 An Enzyme and Metal-Complex Catalysts
Recommended from our members
Further studies on hydration of alkynes by the PtCl4-CO catalyst
Recommended from our members
Further studies on hydration of alkynes by the PtCl4-CO catalyst
Under CO atmosphere, between 80 and 120 C, a glyme solution of PtCl{sub 4} forms a carbonyl compound that promotes hydration of internal as well as terminal alkynes to give aldehyde-free ketones. The catalytic process depends strongly on the electronic and steric nature of the substrates. Part of the carbonyl functions of the catalyst can be replaced by phosphine ligands. Chiral DIOP reacts with the PtCl{sub 4}-CO compound to give a catalyst that promotes partial kinetic resolution of a racemic alkyne. Replacement of part of the CO by polystyrene-bound diphenylphosphine enables to attach the catalyst to the polymeric support. Upon entrapment of the platinum compound in a silica sol-gel matrix, it reacts as a partially recyclable catalyst. A reformulated mechanism for the PdCl{sub 4}-CO catalyzed hydration is suggested on the basis of the present study
Palladium-Catalyzed Cross-Alkynylation of Aryl Bromides by Sodium Tetraalkynylaluminates
Sol-gel entrapped lipophilic and hydrophilic ruthenium-, rhodium-, and iridium-phosphine complexes as recyclable isomerization catalysts
Characterization of Water/Sucrose Laurate/n-Propanol/Allylbenzene Microemulsions
Water/n-propanol/sucrose laurate/allylbenzene micellar systems were formulated and applied in the isomerization of allylbenzene in the presence of heterogenized derivatives of some platinum group catalysts. The ratio (w/w) of n-propanol/surfactant studied herewith was 2/1. Temperature insensitive microemulsions were found. The microemulsions were characterized by the volumetric parameters, density, excess volume, ultrasonic velocity, and isentropic compressibility. The densities increase with increases in the water volume fraction. Excess volumes of the microemulsions decrease for water volume fractions below 0.2, level off for water volume fractions between 0.2 and 0.6 then increase for water volume fractions above 0.6. Excess volumes of the studied micellar systems increase with temperature. Isentropic compressibilities increase with temperature for water volume fractions below 0.8 and decrease for water volume fractions above 0.8. Structural transitions from water-in-oil to bicontinuous to oil-in-water occur along the microemulsion phase. The particle hydrodynamic diameter of the oil-in-water microemulsions at the 0.95 water volume fraction was found to decrease with temperatur