Top shelf dehydration: Ammonium perrhenate catalysts combined with benzylic alcohol reductants are used for the efficient deoxydehydration of glycols to olefins. The olefin and aldehyde products can be easily separated and isolated. It is also demonstrated that the catalyst can be recovered and reused because of its low solubility in aromatic solvents.

The catalytic emulsion polymerization of ethylene has been a long-lasting technical challenge as current techniques still suffer some limitations. Here we report an alternative strategy for the production of semi-crystalline polyethylene latex. Our methodology consists of encapsulating a catalyst precursor within micelles composed of an amphiphilic block copolymer. These micelles act as nanoreactors for the polymerization of ethylene in water. Phosphinosulfonate palladium complexes were used to demonstrate the success of our approach as they were found to be active for hours when encapsulated in micelles. Despite this long stability, the activity of the catalysts in micelles remains significantly lower than in organic solvent, suggesting some catalyst inhibition. The inhibition strength of the different chemicals present in the micelle were determined and compared. The combination of the small volume of the micelles, and the coordination of PEG appear to be the culprits for the low activity observed in micelles.

The development of sustainable chemical processes for the conversion of highly oxygenated biomass feedstocks to chemical products requires efficient and selective processes for partial oxygen removal and refunctionalization. Here we review the development of the deoxydehydration (DODH) reaction, which converts vicinal diols (glycols) to olefins. Uncatalyzed deoxygenative eliminations were first established. The catalyzed DODH reactions have largely employed oxo-rhenium catalysts and a variety of reductants, including PR₃, dihydrogen, sulfite, and alcohols. A variety of glycol and biomass-derived polyol substrates undergo the DODH reaction in moderate to good efficiency, regioselectively, and stereoselectively. Observations regarding selectivity, mechanistic probes, and computational studies support the general operation of a catalytic process involving three basic stages: glycol condensation to an M-glycolate, reduction of the oxo-metal, glycol condensation to produce a metal-glycolate, and alkene extrusion from the reduced metal-glycolate. Recent practical developments include the discovery of non-precious V- and Mo-oxo DODH catalysis.

Several dihydroaromatic compounds are shown to be effective reducing agents in the oxo-metal-catalyzed deoxydehydration of diols and polyols to produce olefins and the corresponding arenes. NH4ReO4 and MeReO3 are active catalysts for the reactions. The most effective of the hydroaromatic reductants is indoline, which is oxidized to indole. Yields for a variety of diols and polyols range from 35% to 99%. Two hydrogen donors, 1,3-cyclohexadiene and dihydroanthracene, engage in tandem DODH/cycloaddition reactions. Competition experiments show that indoline is more reactive than representative alcohols in H-transfer. Indoline is shown to reduce MeReO3 to MeReO2 via an isolable adduct, MeReO3(indoline) (4), which has been structurally characterized and is suggested to be an intermediate in the catalytic DODH process.

Representative benzylic, allylic and α-keto alcohols are deoxygenated to alkanes and/or reductively coupled to alkane dimers by reaction with PPh3 catalyzed by (PPh3)2ReIO2 (1).