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The cross-metathesis of methyl oleate (MO) with ethylene was studied on the second-generation Hoveyda-Grubbs complex supported on silica (HG/SiO2). The reaction was carried out in a batch slurry reactor at 313-353 K and 2.5-7.5 bar of C2H4(5%)/N2, using cyclohexane as solvent. The MO ethenolysis products were methyl 9-decenoate and 1-decene. Competitive MO self-metathesis reaction formed 9-octadecene and methyl 9-octadecen-1,18-dioate. The yield (YE) and selectivity (SE) to ethenolysis products at P C 2 H 4 = 0.125 bar (total pressure = 2.5 bar) were 52% and 69%, respectively. Both parameters increased with P C 2 H 4 , essentially because the reaction equilibrium was shifted to higher methyl oleate conversions. Thus, at P C 2 H 4 = 0.250 bar, the YE and SE values were 63% and 77%, respectively. Nevertheless, catalyst deactivation was observed for ethylene pressures higher than 0.125 bar, thereby suggesting that the presence of ethylene may suppress the metathesis cycle on HG/SiO2 catalysts. The yield to ethenolysis products decreased when the temperature was increased, reflecting mainly the MO equilibrium conversion diminution.

Metallocorroles have emerged as interesting and versatile catalysts for a variety of redox reactions. These include cleanenergy related small-molecule activation reactions such as proton, carbon dioxide and dioxygen reductions, as well as water oxidation, for which their ability to undergo several oxidation processes and reach high formal metal oxidation states makes them attractive catalysts. The diversity of substituent and central metal variations in metallocorroles opens up innumerable possibilities to tailor the properties and reactivity of this family of metallomacrocycles, and the richness of the (electro)chemistry and spectroscopy of metallocorroles allows for an array of instrumental techniques to be applied to the study of various (electro)catalytic processes. In this paper, we will succinctly summarize the synthesis of several cobalt, manganese, and iron metallocorroles with different apical ligands, discuss their redox properties and metal versus ligand centered oxidations through selected examples, and review their application in water oxidation (electro)catalysis. We will discuss some of the factors which affect the catalytic activity, some of the proposed mechanistic features and point out what we consider to be open questions and future perspectives in this field.

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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.