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Peter Hesemann

Publications and source records attributed to Peter Hesemann.

5 recordsLinked to original sources
PubMed2006

Aerobic oxidation of alcohols in carbon dioxide with silica-supported ionic liquids doped with perruthenate.

The replacement of toxic Cr(VI) for O2 and of chlorinated solvents for supercritical carbon dioxide (or ionic liquids) in the oxidation of alcohols remains hindered by the low selectivity and activity of the current heterogeneous catalysts. Using an integrated approach that combines sol-gel entrapped perruthenate as aerobic catalyst, an encapsulated ionic liquid as solubility promoter, and scCO2 as the reaction solvent, we have developed a system capable of rapidly converting different alcohols into carbonyl compounds with complete selectivity, including substrates which are otherwise difficult to oxidise. The methodology is generally applicable and may easily be extended to other waste-free, catalytic syntheses of fine chemicals.

Aerobiosis↗
PubMed2006

Task-specific ionic liquids bearing 2-hydroxybenzylamine units: synthesis and americium-extraction studies.

The synthesis of two task-specific ionic liquids (TSILs) bearing 2-hydroxybenzylamine entities is described. These compounds are based on an imidazolium substructure onto which one hydrobenzylamine-complexing moiety is grafted. We have demonstrated that, whether pure or diluted, TSIL is able to extract americium ions. Furthermore, recovery of americium from the IL phase into a receiving phase can be achieved under acidic conditions. A possible mechanism for the metal-ion partitioning is presented, in which the extraction system is driven by an ion-exchange mechanism.

Journal Article↗
PubMed2006

Extraction of lanthanides from aqueous solution by using room-temperature ionic liquid and supercritical carbon dioxide in conjunction.

For the first time, the study of a three-step extraction system of water/ionic liquid/supercritical CO2 has been performed. Extraction of trivalent lanthanum and europium from an aqueous nitric acid solution to a supercritical CO2 phase via an imidazolium-based ionic liquid phase is demonstrated, and extraction efficiencies higher than 87 % were achieved. The quantitative extraction is obtained by using different fluorinated beta-diketones with and without the addition of tri(n-butyl)phosphate. The complexation phenomenon occurring in the room-temperature ionic-liquid (RTIL) phase was evidenced by using luminescence spectroscopy.

Journal Article↗