TBA Cations Research Articles

New organic electrolytes: tris(dialkylamino)sulfonium salts: (R 2N 3)S +X μ

The electrochemical and electrical properties of tris(dimethylamino)sulfoniuin tetrafluoroborate (TASBF 4),a representative example of a new class of tris(dialkylamino)sulfonium salts, are described. Conductivity and cyclic voltammetric measurements were conducted in both CH 3CN and CH 2Cl 2, and the results were compared with those of tetrabutylammonium tetrafluoroborate (TBABF 4). The peak separation of the Fc/Fc + couple is smaller with the TAS salt than with the TBA salt. The effect of electrolyte concentration and sweep rate on the peak separation is discussed. From conductivity measurements, the dissociation constants of TASBF 4 in both solvents are 20–30% larger than those of TBABF 4. The limiting conductivity of the TAS cation in CH 3CN (102 S cm 2 mol −1) is about 60% higher than that of the TBA cation.

Catalytic photooxidation of some secondary alcohols by decatungstate isopolyanion and Keggin-type dodecatungstophosphate heteropolyanion in homogeneous system under excess of oxygen and the effect of counterions on redox cycle of polyanions

Under excess of oxygen, catalytic photooxidation of secondary alcohols to ketones, initiated by irradiation of charge-transfer bands of polyanions such as decatungstate isopolyanion and Keggin-type heteropolytungstophosphate, has been investigated. Photooxidation of organic substrates proceeds in conjunction with photoreduction of polyanions and the catalytic cycle is attained by reoxidation of reduced polyanions by the reaction with O 2, where consumed O 2 is converted to water. Polyanions studied are H 3 [PW 12O 40] and K 4 [W 10O 32] which are soluble in water, and (TBA) 3 [PW 12O 40] and (TBA) 4− [W 10O 32] (TBA=tetrabutylammonium) which are soluble in acetonitrile. Organic substrates studied are secondary alcohols such as isopropyl alcohol, cyclohexanol and ethyl lactate. Catalysis by the Keggin polyanion is based on the redox cycle between the one-electron (1e) reduced species and the oxidized form, whereas that by the decatungstate is based on the redox cycle between the 2e-species and the oxidized form. These two cycles are strongly influenced by the counterion. This is interpreted in that some of the TBA cations are binding with the polyanions in acetonitrile solution.

Reversed-Phase Separation of the Major Deoxyribonucleosides and Their Mononucleotides Using Tetrabutylammontum Hetaerons

Abstract Simultaneous separation of the four major deoxyribonucleosides and their monophosphate nucleotides was achieved using tetrabutyl ammonium phosphate hetaerons with a reversed-phase (C8) packing material. Baseline resolution for all eight solutes was achieved within 48 minutes, using a 7.5% methanol mobile phase, 2.0 mM in TBA, buffered with 50 mM phosphate at pH 4.8. The effect of methanol and TBA concentrations upon the retention of neutral and anionic solutes was studied in detail. It was determined that changes in solute k' with increasing methanol could be explained by essentially independent phenomena. These are: 1) a decrease in the partition coefficient of the TBA cation with increasing organic concentration, resulting in lower surface charge densities, and 2) a decrease in the hydrophobic interactions of the solutes with the reversed-phase HPLC. The overall effect was a log-linear decrease in k' with increasing methanol concentration. An empirical equation was derived for the above model w...