Platinum-based polymeric microreactors for hydrosilylation of alkynes in water
Platinum acetylacetonate was encapsulated within polyurea microcapsules and utilized in the hydrosilylation of acetylenes after treatment with hydrogen. The encapsulation process is based on the emulsification of dichloromethane containing Pt(acac)2 and polyisocyanate monomer in water followed by interfacial polyaddition reaction that occurs after adding diamine monomer to the emulsion. The resulting catalytic microcapsules were characterized by SEM, solid NMR, TGA and FT-IR spectroscopy.
Hydrosilylation of unsaturated organic compounds is an important industrial reaction for manufacturing organosilicon monomers, which are important building block for silicones, surfactants, lubricants and adhesives (1-4).
Hydrosilylation of alkynes yields alkenylsilanes, which are important monomers for building new and reactive materials (5-8). The hydrosilylation has been investigated intensively using various catalysts mainly under homogeneous conditions (9-15). Among these catalysts, platinum-based catalysts have showed excellent reactivity and selectivity in this transformation (16). However, the difficulties in the separation of the homogenous catalysts led to developing heterogeneous platinum catalysts to enable recyclability and reduction in the costs of the catalytic transformation (17-22). For example, Alonso et al demonstrated the immobilization of platinum on titania and its utilization in the hydrosilylation of various terminal and internal alkynes at 70 °C and at room temperature (23). The catalyst demonstrated high regioselectivity and full conversions in the absence of a solvent. The catalyst was recovere ...