|
| |
|
|
Quaternary Ammonium Salts in Asymmetric Hydrogenations – Additives, Reaction and Immobilization Media
Floriš, T. ; Klusoň, Petr ; Muldoon, M.J.
The inhibited catalytic activity of Ru-BINAP in MAA hydrogenation through ILs based on anion derivates of acids with higher pKa revealed a side way in the application of the ILs produces from renewable sources, (chiral) carboxylates (betaine, lactates) in genaral. On the other hand the employment of structurally modified quaternary ammonium cations seems to be the perspective route not only in optical yeld increase. Thus quaternary ammonium bromides such as chorides satisfied the reaction parameters enhancement. On the basis of our previous results, envirnmentaly benign choline chloride was applied as a crucial additive in optimized solvent system composed of methanol, CO2 and water.
|
|
|
Asymmetric Hydrogenation Reactions
Klusoň, Petr ; Floriš, T.
In this contribution some information on the research of catalytic properties of homogeneous Ru catalysts are presented. Most attention is paid to the BINAP complexes and their coexistence with ionic liquids as potential reaction media for such hydrogenations.
|
|
|
Voltammetric measurement of H.sub.2./sub.O.sub.2./sub. concentration in aqua-organic solutions
Kurc, L. ; Floriš, T. ; Josypčuk, Bohdan
In this work was tested the applicability of voltammetry and of meniscus silver solid amalgam electrode for determination H2O2 in presence of organic species (solvent, substrate or product of Baeyer-Villiger oxidation of cycloketones to lactones). Hydrogen peroxide can be measured in its wide concentration interval in different aqua-organic solutions. The slope of H.sub.2./sub.O.sub.2./sub. concentration dependence decreases with increasing 1,4-dioxane concentration. 1,4-dioxane in mixture with water can be used up to its concentration 80 vol. %. Model species, which represent reactants and products of Baeyer-Villiger oxidation, influence calibration dependence individually and their effect is not possible to estimate. Hence, quantitative hydrogen peroxide determination in probes of reactive mixture, which have different composition, should be carried out by standard addition method.
|
guest ::
