Poly(dimethylsiloxane)-Based Recyclable Tablet Catalysts Bearing Gold N-Heterocyclic Carbene Complexes for Alkyne Hydration Reactions

The tablet-based catalytic systems offer various advantagessuchas improved stability, ease of handling, and dosage delivery of transitionmetal catalysts for organic transformation reactions. The traditionalparaffin wax-based tablet catalysts are useful in storing and dosagedelivery of organometallic catalysts; however, the recycling of thecatalyst is not possible due to the solubility of wax in common organicsolvents. In this study, we have developed poly(dimethylsiloxane)(PDMS)-based recyclable tablet catalyst systems bearing gold(I) N-heterocycliccarbene complexes for alkyne hydration reactions in the aqueous medium.Commercial PDMS rods, room-temperature vulcanizable universal silicones,and Pattex were used as tablet materials. The tablet catalysts showedhigh performance in the hydration of both alkyl and aryl acetylenederivatives and can easily be isolated from the reaction media inthe solid phase. The tablet catalyst can be reused up to the 13thturn in the hydration of phenylacetylene in a methanol/water medium.

Automated summary

The tablet-based catalytic systems offer improved stability, ease of handling, and dosage delivery of transition metal catalysts for organic transformation reactions. However, the traditional paraffin wax-based tablet catalysts cannot be recycled due to their solubility in common organic solvents. This study developed recyclable tablet catalyst systems based on poly(dimethylsiloxane) (PDMS) containing gold(I) N-heterocyclic carbene complexes for alkyne hydration reactions in aqueous medium. The tablet catalysts showed high performance and can be easily isolated from the reaction media in solid phase.