Non-catalytic Oppenauer oxidation of alcohols in supercritical water

Fusel oil reaction in pressurized water: characterization and antimicrobial activity

This work aimed to investigate the reaction of fusel oil (FO) with pressurized water in a continuous flow reactor, in order to verify the effect of operating conditions (temperature and alcohol to water ratio) on the formation of reaction products, as well as to potentiate the antimicrobial activity of FO. The characterization of the FO was performed by high resolution mass spectrometry (ESI-TOF) and by a chromatograph coupled to mass spectrometry (GC-MS), and the reaction products were characterized by ESI-TOF and evaluated for antifungal potential. From the results, it was verified that the FO contained 70.58 wt% of isoamyl alcohol and was formed mainly by the organic functions alcohols, aldehydes, ketones and lipids. The reaction mechanisms that prevailed during the reactions conducted in subcritical and supercritical states were dehydration and reduction, respectively, making it possible to identify pyrazine derivatives compounds in the reaction products. The fungus Irpex lacteus showed greater resistance under the application of reaction products, and the products obtained at 300 °C and 400 °C showed an inhibition percentage of 96.07% to Schizophyllum commune and 96.50% to Trametes versicolor, respectively.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03429-3.

Chemical reactions of organic compounds in supercritical water gasification and oxidation

Supercritical water is a benign reaction medium to convert organic matters through supercritical water gasification and supercritical water oxidation into flammable gaseous and harmless substances, respectively. This work systematically summarizes main chemical reactions of some typical organic compounds in supercritical water with or without oxidant for the first time. These compounds include hydrocarbons, proteins, cellulose, lignins, phenols, alcohols, aldehydes, ketones, organic acids, and some N-, Cl-, Br-, F-, S- and P-containing organic matters. Their main conversion pathways, reaction processes, intermediate products, final products and influence factors are analyzed deeply. This information helps to understand and predict corresponding reaction mechanisms and to better achieve objective products in supercritical water gasification and supercritical water oxidation.

Kumada-Grignard-type biaryl couplings on water

Well-established, traditional Kumada cross-couplings involve preformed Grignard reagents in dry ethereal solvent that typically react, e.g., with aryl halides via Pd catalysis to afford products of net substitution. Therefore, in the work described, which appears to be counterintuitive, exposure of these same aromatic halides to catalytic amounts of Pd(II) and excess magnesium metal in pure water leads to symmetrical/unsymmetrical biaryls, indicative of a net Kumada-like biaryl coupling. Evidence is presented suggesting that Grignard reagents, formed in situ in water, may be involved.

Organomagnesium reagents have been a staple for carbon–carbon bond formations for over a century, but are notoriously sensitive to water. Here, the authors show a Kumada-type coupling of aryl halides on water, with a potential intermediary of an in situ formed Grignard reagent.