17 research outputs found
Legislative Documents
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Homogeneous electron-transfer reaction between electrochemically generated ferrocenium ions and amine-containing compounds
The homogeneous catalytic oxidation of propylamine (PrA), diethylamine (DEA), pyrrolidine (Pyr), and triethylamine (TEA) has been investigated for the first time in the presence of electrochemically generated ferrocenium ions as the catalyst. Mechanistic details for this electrocatalytic process have been investigated by cyclic voltammetry and other electrochemical techniques. A one-electron oxidative process was observed for all amines. Deviation from this mechanism was only observed during controlled-potential bulk electrolysis of ferrocene in the presence of high concentrations of propylamine, where problems with electrode fouling and catalyst deactivation processes were encountered. The catalytic efficiency and the catalytic oxidation rate constants were estimated and found to follow the order TEA > Pyr > DEA > PrA. Interestingly, the catalytic reaction was not observed when ferrocene was replaced by decamethylferrocene. This observation was analyzed in terms of thermodynamic and structural effects, and a hypothesis is presented. The homogeneous catalytic oxidation reported opens a new avenue to achieve simple, low-cost, and efficient amine oxidation, which is potentially useful in several areas of chemistry
Application of low field and solid-state NMR spectroscopy to study the liquid/liquid interface in porous space of clay minerals and shales
In petroleum research understanding displacement, redistribution, and adsorption of oil and water plays an important role. To study complex multi-component systems such as liquid/liquid/mineral interactions in the porous space of clays and shales we applied low
field (2 – 15 MHz) and high resolution (300 MHz) NMR spectroscopy. The detailed NMR analysis shows that the results from low field NMR measurements are in good correlation with the solid-state data. Consequently the process of liquid/liquid displacement can be characterised by considering the relaxation times, signal amplitudes and chemical shifts together
Extraction of silver(i) from aqueous solutions in the absence and presence of copper(ii) with a methimazole-based ionic liquid
The ionic liquid (IL) 2-butylthiolonium bis(trifluoromethanesulfonyl)amide, [mimSBu][NTf2], facilitates the efficient extraction of silver(i) from aqueous media via interaction with both the cation and anion components of the IL. Studies with a conventional aqueous-IL two phase system as well as microextraction of silver(i) by a thick IL film adhered to an electrode monitored in situ by cyclic voltammetry, established that [mimSBu][NTf2] can extract electroactive silver(i) ions from an aqueous solution. The pH of the aqueous phase decreases upon addition of [mimSBu]+, which is attributed to partial release of the hydrogen attached to the N(3) nitrogen atom of the imidazolium ring. The presence of silver(i) further increase the acidity of the aqueous phase as a consequence of coordination with the IL cation component. Voltammetric and 1H and 13C NMR techniques have been used to establish the nature of the silver(i) complexes extracted, and show that the form of interaction with the IL differs from that outlined previously for the extraction of copper(ii). Insights on the competition established when silver(i) is extracted in the presence of copper(ii) are provided. Finally, it is noted that metallic silver can be directly electrodeposited at the electrode surface after extraction of silver(i) into [mimSBu][NTf2] and that back extraction of silver(i) into aqueous media is achieved by addition of an acidic aqueous solution.<br /
Non-additivity of Faradaic and capacitance terms in ionic liquids
A study was conducted to evaluate the unexpected non-additivity of Faradaic and capacitance currents encountered in the case of ionic liquids. The results highlight that the non-additivity of Faradaic and capacitance currents should be considered in IL electrochemistry when multiple solutes are present
Homogeneous Electron-Transfer Reaction between Electrochemically Generated Ferrocenium Ions and Amine-Containing Compounds
The
homogeneous catalytic oxidation of propylamine (PrA), diethylamine
(DEA), pyrrolidine (Pyr), and triethylamine (TEA) has been investigated
for the first time in the presence of electrochemically generated
ferrocenium ions as the catalyst. Mechanistic details for this electrocatalytic
process have been investigated by cyclic voltammetry and other electrochemical
techniques. A one-electron oxidative process was observed for all
amines. Deviation from this mechanism was only observed during controlled-potential
bulk electrolysis of ferrocene in the presence of high concentrations
of propylamine, where problems with electrode fouling and catalyst
deactivation processes were encountered. The catalytic efficiency
and the catalytic oxidation rate constants were estimated and found
to follow the order TEA > Pyr > DEA > PrA. Interestingly,
the catalytic
reaction was not observed when ferrocene was replaced by decamethylferrocene.
This observation was analyzed in terms of thermodynamic and structural
effects, and a hypothesis is presented. The homogeneous catalytic
oxidation reported opens a new avenue to achieve simple, low-cost,
and efficient amine oxidation, which is potentially useful in several
areas of chemistry
Physical and electrochemical properties of thioether-functionalized ionic liquids
The preparation and characterization of a series of ionic liquids based on S-alkyl thiolonium, S-alkyl thiotetrazolium, or S-alkyl thiobenzolium cations coupled with bis(trifluoromethanesulfonyl)amide, trifluoromethanesulfonate, alkyl phosphate, chloride, and hexafluorophosphate anions are reported. All are liquid at room temperature, except the chloride salt, which has a melting point of 92 °C. The electrochemical characteristics of this class of ionic liquid have been determined by cyclic voltammetry. Potential windows of the ionic liquids have been obtained at glassy carbon, platinum, and gold electrodes and found to be the largest at glassy carbon, but are limited by oxidation of the thioether-functionalized cation. The voltammetry of IUPAC reference potential scale systems, ferrocene/ferrocenium, cobaltocenium/cobaltocene, and decamethylferrocene/decamethylferrocenium have been evaluated, with the last being most widely applicable. Nonadditivity of Faradaic current is found in the voltammograms of decamethylferrocene in the presence of ferrocene and cobaltocenium. Diffusion coefficient, viscosity, ionic conductivity, double layer capacitance, and other physical properties have also been measured. The dependence of the diffusion coefficient vs viscosity follows the Stokes−Einstein relationship. The properties of the ionic liquids are compared with the related imidazolium family of ionic liquids.<br /