BMIm-PF<sub>6</sub>@SiO<sub>2</sub> Microcapsules:
Particulated Ionic Liquid as A New Material for the Heterogenization
of Catalysts
- Publication date
- Publisher
Abstract
A method
for the preparation of silica microcapsules containing
a high loading of ionic liquids (ILs) is described. The method paves
the way to the conversion of ionic liquids into particulated materials,
which results in ILs with new properties without changing their molecular
structures. The synthesis of these new materials is based on the emulsification
of ionic liquids in water, using surfactants or dispersants, and the
resulting ionic liquid droplets are then confined in a silica shell
formed via interfacial hydrolysis and polycondensation of tetraethoxysilane.
This material can be isolated by centrifugation, followed by drying
to yield a fine powder of ionic liquid-silica microcapsules, which
are water and organic solvents redispersible. These new materials
are utilized in the heterogenization of palladium catalyst and then
applied in the hydrogenation of alkynes. The catalyst shows chemoselectivity
in the hydrogenation of internal alkynes such as 4-octyne. Comparative
studies have shown that the same catalyst loses this selectivity when
it is applied under homogeneous conditions