Stability of a Silica-Supported Second Generation Hoveyda-Grubbs Catalyst Under Atmospheric Conditions: Experimental and Computational Studies

Second generation Hoveyda-Grubbs (HG(2)) is a reliable and extremely useful catalyst for the synthesis of olefins. Recent studies show that supported HG(2) catalyst is particularly well suited for the self-metathesis reaction of unsaturated fatty acid methyl esters, such as methyl oleate (MO), among other applications. Within the various supports that have been studied, silica gel appears as one of the most promising for large scale application of heterogeneous HG(2). In this work we found that although the catalyst supported on silica gel retains its activity when stored under strictly controlled conditions (vacuum, 253 K), the activity deeply decreases when the supported complex is stored under atmospheric conditions at 298 K, compromising the stability and applicability of the heterogeneous catalyst. We carried out a detailed experimental and spectroscopic study of the deactivation process of the supported catalyst, which, aided by electronic structure calculations, allowed us to throw some light onto the catalyst decomposition process.