Carboxylic acids are ubiquitous in chemistry and find use in a variety of applications in both industry and in academic research, including as polymer precursors, synthetic building blocks, and food preservatives. Modern routes to synthesize these compounds often involve harsh conditions or reagents harmful to both the environment and human health. An alternative synthetic route is the aldehyde-water shift reaction; in this relatively unknown reaction, an aldehyde is oxidized by water to a carboxylic acid with release of molecular hydrogen. The use of water as both solvent and reagent and the mild reaction conditions could potentially reduce the impact of aldehyde oxidation on the environment.<br/><br/>Two major classes of half-sandwich catalysts for this reaction have been investigated for activity in catalyzing this reaction with a variety of aldehyde substrates: one series includes a bipyridine derivative with Ir(III), Rh(III), and Ru(II) metal centers, while the other series features diamine ligands on Ru(II). Using <sup>1</sup>H NMR and GC-FID to analyze reaction products, many of the catalysts were observed to disproportionate aldehydes to alcohols and carboxylic acids in competition with the desired dehydrogenative oxidation to carboxylic acids. Mechanistic studies and catalyst optimization for selective dehydrogenative oxidation are presented.

Oxidizing aldehydes with water: Catalysts for the aldehyde-water shift

249th National Meeting (2015)

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