Oxidative Homocoupling of Alkynes Using Supported Ionic Liquid Phase (SILP) Catalysts - Systematic Investigation of the Support Influence

Abstract

Supported Ionic Liquid Phase (SILP) catalysts have been prepared by effective immobilization of [Cu(TMEDA)(OH)]Cl in a nano-metric film of an ionic liquid on various oxidic support materials. The catalysts were tested for the oxidative homocoupling of 1-alkynes to the corresponding diynes in in a combined high throughput and conventional batch reaction approach. Among the screened support materials silica based materials performed best. The results indicate that for the specific reaction the thickness of the ionic liquids layer and therefore the mobility of the homogeneous copper complex within the ionic liquid layer as deduced from solid state nmr measurements have major impact on the catalytic performance. The optimized catalysts could be recycled up to four times without any loss of activity.

Heterogeneous Catalytic Homocoupling of Terminal Alkynes

“…52−54 Very recently, the group of Szesni prepared a wide range of SILP catalysts by immobilization of [Cu(TMEDA)(OH)]Cl in a nanometric film of an ionic liquid on various supports. 55 The homocoupling of phenylacetylene was studied for catalyst screening, using 5 mol % Cu in hexane at room temperature for 72 h under synthetic air. A gradual increase in the activity of the tested catalysts was shown with decreasing surface area of the parent support material, reaching a maximum for medium surface areas (80−180 m 2 g −1 ).…”

“…Supported ionic liquid phase (SILP) catalysts consist of homogeneous catalysts or catalysts precursors immobilized in a thin film of an ionic liquid on the surface of a porous carrier material by physisorption, ionic or covalent anchoring. − Very recently, the group of Szesni prepared a wide range of SILP catalysts by immobilization of [Cu(TMEDA)(OH)]Cl in a nanometric film of an ionic liquid on various supports . The homocoupling of phenylacetylene was studied for catalyst screening, using 5 mol % Cu in hexane at room temperature for 72 h under synthetic air.…”

Efficient alkyne homocoupling catalysed by copper immobilized on functionalized silica

“…While there are many good examples of catalytic acetylenic homocoupling, catalyst recovery and recycling are problematic. This is especially true in the case of homogeneous catalysis, where catalyst separation can be more labour‐intensive and costly than the reaction itself .…”