Tetrafluoroborate, as supporting electrolyte

Ding, S.F., Xu, M.Q., Zhao, G.C., and Wei, X.W., Direct electrochemical response of Myoglobin using a room temperature ionic liquid, l-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate, as supporting electrolyte, Electrochem. Commun., 9, 216-220,2007. 

Electrochemical cathodic reductions of acetylcyclopropanes in ammonia solution, with butyl-trimethylammonium tetrafluoroborate as supporting electrolyte, gave the same products as in the lithium/ammonia reductions. However, when tetraethylammonium tetrafluoroborate was employed, tertiary alcohols, e.g. 33 were isolated. The ethyl groups were probably incorporated by anionic attack on the initially formed ketones. 

Acetonitrile was also used as the solvent for the first successful synthesis of a PAn/PPy copolymer via galvanostatic (constant-current) electropolymerization of mixtures of aniline (0.5 M) and pyrrole (0.1-1.0 M) in acetonitrile solvent in the presence of CF3COOH as acid and tetraethylammonium tetrafluoroborate as supporting electrolyte. Differential scanning calorimetry and Fourier transform infrared (FTIR) measurements confirmed that the electrically conducting product was a mixture of PAn, PPy, and a random PAn/PPy copolymer.36... 

M tetrafluoroborate as supporting electrolyte. (Reproduced by permission of Marcel Dekkerfrom C. Amatore, Electrochemistry at Microelectrodes, Ed. 

Figure 6.1.4.2 Theoretical limitations on ultrafast cyclic voltammetry. The shaded area between the slanted lines represents the radius that a microdisk must have if the ohmic drop is to be less than 15 mV and distortions due to nonplanar diffusion account for less than 10% of the peak current, (a) Without iR drop compensation by positive feedback, and (b) with 90 and 99% ohmic drop compensation. The dotted area in (a) and (b) represent the regions where transport within the double layer affects the voltammetric response. Limits are indicative and correspond approximately to a 5-mM anthracene solution in acetonitrile, 0.3 M tetrafluoroborate as supporting electrolyte. [Reproduced by permission of Marcel Dekker from C. Amatore, Electrochemistry at Microelectrodes, I. Rubenstein, Ed., 1995, Chapter 4, p. 198.]...

For the electrochemical measurements reported herein, all cyclic voltammetry measurements are performed in CH2C12 with 0.1 M tetra-n-butylammonium tetrafluoroborate (Bu4NBF4) as supporting electrolyte, while measurements in CH3CN use 0.1 M tetra-ethylammonium perchlorate. Cyclic voltammetry measurements are performed in a three-electrode, one-compartment cell equipped with a Pt working electrode, a Pt auxiliary electrode, and a saturated sodium chloride calomel (SSCE) reference electrode. E1 2 = (Ep.a + Ep.c)/2 AEP = Ep,e - Ep,a-Ei/2 and AEP values are measured at 100 mV/sec. Ferrocene is used as a reference in the measurement of the electrochemical potentials. 

In dry acetonitiile/sodium perchlorate, however, sodium methanesulfonate and CO is obtained. A methylthiomethyl cation 159, (Eq. (220) ), is believed to be an intermediate, which is hydrolyzed to formaldehyde and methyl mercaptane. Both products are subsequently oxidized by C1207, formed by dehydration of perchloric acid, to CO and NaS03CH3 465 In spite of the fact that epe was conducted well below the discharge potential of the supporting electrolyte complications arose (Eq. (220) ), that were attributed to anodically generated C104 This observation asks for caution in the use of perchlorates as supporting electrolytes in apro-tic solvents. If possible, tetrafluoroborates or hexafluorophosphates should be used instead. 

Tetrahexylammonium perchlorate and tetrabutylammonium tetrafluoroborate have been used as supporting electrolyte in benzene and chlorobenzene, respectively. The latter was suggested [418] to be an excellent solvent for the study of reversible oxidations and reductions of aromatic compounds. The TLV for chlorobenzene is 75 ppm. 

The general electrochemical procedure for the carbon dioxide incorporation was based on the use of one-compartment cells fitted with consumable anodes of magnesium or zinc [12]. Electrocarboxylations were carried out in DMF at constant current density, using tetrabutylammonium tetrafluoroborate (10 2 m) as supporting electrolyte. The catalyst was introduced in a 10% molar ratio with respect to the substrate and carbon dioxide was bubbled through the solution at atmospheric pressure. Electrolyses were generally run at room temperature and reactions were stopped when starting material was consumed or when the faradaic yield attained 30%. 

A divided cell equipped with a sintered glass separator, a carbon fiber anode, and a platinum cathode is used in order to avoid the electrochemical reduction of anodically generated carbocations. Tetrabutylammonium tetrafluoroborate is usually used as supporting electrolyte, and dichloromethane is in most cases suitable as solvent because of less nucleo-philicity and low viscosity at low temperature. Two equivalent of TfOH (trifluoromethane-sulfonic acid) to a cation precursor is added in the cathodic chamber to facilitate the reduction of protons in the cathodic process. The constant current electrolysis (20 mA) was then carried out at —78 °C with magnetic stirring until 2.0-2.5 F/mol of electricity was consumed to give a cation pool. Carbamates (oc-silyl carbamate) (Scheme 2a) [3], a-silyl ethers (Scheme 2b) [4], diarylmethanes (silylated diary Imethanes) (Scheme 2c) [5] can be... 

Cathodic reductions can be carried out at platinum electrodes if the measurement proceeds in aprotic media, e.g., in dimethylformamide or acetonitrile and with tetraalkylammonium salts (perchlorates, tetrafluoroborates, hexafluorophosphates) as supporting electrolytes. A sufficient electron affinity of the hydrocarbon is necessary. The process can be best exemplified by the reduction of 9,10-diphenyl-anthracene in n-Bui+NC10i+ at a Pt microelectrode ... 

Recently, there has been considerable interest in developing molten salts that are less air and moisture sensitive. Melts such as l-methyl-3-butylimidazolium hexa-fluorophosphate [211], l-ethyl-3-methylimidazolium trifluoromethanesulfonate [212], and l-ethyl-3-methylimidazolium tetrafluoroborate [213] are reported to be hydro-phobic and stable under environmental conditions. In some cases, metal deposition from these electrolytes has been explored [214]. They possess a wide potential window and sufficient ionic conductivity to be considered for many electrochemical applications. Of course if one wishes to take advantage of their potential air stability, one loses the opportunity to work with the alkali and reactive metals. Further, since these ionic liquids are neutral and lack the adjustable Lewis acidity common to the chloroaluminates, the solubility of transition metal salts into these electrolytes may be limited. On a positive note, these electrolytes are significantly different from the chloroaluminates in that the supporting electrolyte is not intended to be electroactive. 

Dibenzyl ditellurium was obtained in 70% yield by alkylation of the electrochemically generated ditelluride dianion with benzyl chloride in acetonitrile3. The ultrasonically promoted electrochemical reduction of tellurium powder was performed in H-type cells with the compartments separated by glass frits. Acetonitrile served as solvent and tetrabutylammonium tetrafluoroborate or hexafluorophosphate as the supporting electrolyte. At potentials beyond -1.1 V the dark-red ditelluride dianion is formed in the cathode and in the central compartment3. 

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