PMO‐Immobilized AuI–NHC Complexes: Heterogeneous Catalysts for Sustainable Processes

• Published in: Chemphyschem 2018-02, Vol.19 (4), p.430-436
• Main Authors: De Canck, Els, Nahra, Fady, Bevernaege, Kevin, Vanden Broeck, Sofie, Ouwehand, Judith, Maes, Diederick, Nolan, Steven P., Van Der Voort, Pascal
• Format: Article
• Language: English
• Subjects: alkyne hydration; Alkynes; Catalysis; Catalysts; Chemical synthesis; Gold; heterogeneous catalysis; N-heterocyclic carbene; periodic mesoporus organosilica; Sulfonic acid
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201701102

A stable periodic mesoporous organosilica (PMO) with accessible sulfonic acid functionalities is prepared via a one‐pot‐synthesis and is used as solid support for highly active catalysts, consisting of gold(I)‐N‐heterocyclic carbene (NHC) complexes. The gold complexes are successfully immobilized on the nanoporous hybrid material via a straightforward acid–base reaction with the corresponding [Au(OH)(NHC)] synthon. This catalyst design strategy results in a boomerang‐type catalyst, allowing the active species to detach from the surface to perform the catalysis and then to recombine with the solid after all the starting material is consumed. This boomerang behavior is assessed in the hydration of alkynes. The tested catalysts were found to be active in the latter reaction, and after an acidic work‐up, the IPr*‐based gold catalyst can be recovered and then reused several times without any loss in efficiency. Boomerang effect: Gold(I)‐N‐heterocyclic carbene (NHC) complexes are successfully immobilized on PMO materials via straightforward acid–base reactions with the corresponding [Au(OH)(NHC)] synthon. This catalyst design strategy results in a boomerang‐type catalyst for the hydration of alkynes. The catalyst can be recovered and then reused several times without any loss in efficiency.