A green and efficient hydration of alkynes catalyzed by hierarchically porous poly(ionic liquid)s solid strong acids

Abstract

The catalytic conversion of alkynes into ketones via hydration has received considerable attention, because the ketones are very important intermediates in the chemical and pharmaceutical industries. The hydration of alkynes was usually performed with rather complicated processes in presence of liquid acids or highly toxic metal catalysts. We report here a novel metal free and efficient route to conversion of alkynes into ketones catalyzed by hierarchically porous poly(ionic liquid)s solid strong acids, which were synthesized from one-step, template-free copolymerization of divinylbenzene (DVB) with nitrogen containing monomers under solvothermal condition, further by post grafting with strong acid ionic liquid groups. The porous poly(ionic liquid)s solid acids have large BET surface areas, hierarchical nanopores and enhanced acid strength. A variety of alkynes could be effectively transformed into ketones catalyzed by the synthesized porous poly(ionic liquid)s solid acids under green and mild conditions, which were much better than those of Amberlyst 15, phosphotungstic acid and sulfuric acid. Furthermore, the porous poly(ionic liquid)s solid acids also show excellent activities and good reusability in direct hydroamination of amines with phenylacetylene. This work largely expands the wide applications of porous poly(ionic liquid)s solid strong acids in hydration and hydroamination, which develops a green, efficient and cost effective approach for conversion of low cost alkynes into high-value added ketones.