Cu3(BTC)2 catalyzed dehydrogenative coupling of dimethylphenylsilane with phenol and homocoupling of dimethylphenylsilane to disiloxane

Abstract

Cu₃(BTC)₂ (BTC: 1,3,5-benzenetricarboxylic acid) showed to be an efficient and reusable heterogeneous solid catalyst for the formation of SiO bond through dehydrogenative coupling of dimethylphenylsilane (1) with phenol under mild reaction conditions. It is observed that Fe(BTC), MIL-101(Cr) and UiO-66(Zr) are not able to promote this cross coupling between 1 and phenol. Cu₃(BTC)₂ exhibits higher stability and activity compared to other MOFs studied here. Furthermore, Cu₃(BTC)₂ is reused for three consecutive cycles with a slight decay in its activity. Comparison of the powder XRD patterns of the fresh with three times used Cu₃(BTC)₂ showed no significant difference in the crystalline structure, thus, indicating the catalyst stability under the optimized reaction conditions. Furthermore, EPR, FT-IR and SEM images of the fresh and reused Cu₃(BTC)₂ did not show any change in the oxidation state of copper or structural morphology. Also, no leaching of copper is detected under optimized reaction conditions. In addition, Cu₃(BTC)₂ showed higher activity compared to Pt, Pd, Au and Cu supported on active carbon as heterogeneous catalysts in the synthesis of disiloxane from 1 through SiH activation.

Keywords: Cu(3)(BTC)(2); Green chemistry; Heterogeneous catalysis; SiO coupling; Silanes.