Paulo Anselmo Ziani Suarez

Water-induced accelerated ion diffusion: voltammetric studies in 1-methyl-3-[2,6-(S)-dimethylocten-2-yl]imidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate and hexafluorophosphate ionic liquids

The electrochemical properties of the room temperature ionic liquids 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM+BF4−), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM+PF6−) and 1-methyl-3-[2,6-(S)-dimethylocten-2-yl]imidazolium n tetrafluoroborate (MDIM+BF4−) as solvents have been studied using micro-samples, with a volume of 10 μL, of the ionic liquids under vacuum conditions and under conditions with controlled gas and moisture supplies. The impact of water—absorbed into the ionic liquid in a controlled manner from the gas phase—on n the voltammetry of dissolved redox systems and on the accessible potential window of the ionic liquids was investigated. The diffusion coefficients for three representative redox systems, the oxidation of neutral N,N,N′,N′-tetramethyl-p-phenylenediamine n (TMPD), the reduction of cationic methyl viologen (MV2+) and reduction of anionic hexacyanoferrate(III), Fe(CN)63−, have been determined as a function of the water content of the ionic liquids. Water n is shown to have a much more dramatic acceleration effect on the diffusion of the ionic compounds compared to its effect on neutral species in ionic liquids. A model based on nanoscale structural features of wet ionic liquid materials n is proposed. The novel methodology, which employs redox-active compounds dissolved or partitioned in microdroplets of ionic liquid, uses conditions suitable for the study of ionic liquids for applications in electrochemical gas phase reactors and gas sensor n systems.

Enlarged electrochemical window in dialkyl-imidazolium cation based room-temperature air and water-stable molten salts

The electrochemical windows of the ionic liquids 1-n-butyl-3-methyl imidazolium tetrafluoroborate (BMI+)(BF4−) and 1-butyl-3-methyl imidazolium hexafluorophosphate (BMI+)(PF6−) have been investigated at platinum, vitreous carbon, tungsten and gold electrodes. The lowest current densities and widest electrochemical windows were found on tungsten and vitreous carbon 6.10 and 5.45 V for (BMI+)(BF4−) and >7.10 and 6.35 V for (BMI+)(PF6−), respectively.

Electrochemical Behavior of Vitreous Glass Carbon and Platinum Electrodes in the Ionic Liquid 1-n-Butyl-3-Methylimidazolium Trifluoroacetate

The 1-n-butyl-3-methylimidazolium trifluoroacetate ionic liquid electrochemical windows have been investigated at vitreous carbon and platinum disc electrodes under static and dynamic conditions. The electrochemical window abruptly decreases by changing vitreous carbon (4.50 V) by platinum electrode (2.50 V). Electrode rotation and potential sweep rate did not affect the current-potential profiles but alter the current values of both anodic and cathodic peaks. The adsorption of imidazolium cation involved in the charge transfer process during the cathodic sweep rate was evidenced, mainly at low electrode rotation.

Pd(II)-dissolved in ionic liquids: a recyclable catalytic system for the selective biphasic hydrogenation of dienes to monoenes

Bis-acetilacetonato de paladio dissolvido no liquido ionico tetrafluoroborato de 1- n-butil-3metilimidazolio catalisa de forma seletiva a hidrogenacao de dienos conjugados e nao-conjugados (funcionalizados ou nao) as suas respectivas mono-olefinas. O sistema nao requer o uso de cosolventes orgânicos, sendo os produtos da reacao separados por simples decantacao ou destilacao. A fase ionica pode ser reutilizada ate 15 vezes sem perdas significativas na sua atividade catalitica e seletividade. Palladium acetylacetonate dissolved in 1- n-butyl-3-methylimidazolium tetrafluoroborate ionic liquid catalyses the selective two-phase hydrogenation of conjugated and non-conjugated (functionalized and non-functionalized) dienes into the respective monoenes. The system does not require the use of organic solvents, the products are removed by simple decantation or distillation and the recovered ionic catalytic solution can be reused several times without any significant changes in its catalytic activity and selectivity.

Organo-zincate molten salts as immobilising agents for organometallic catalysis

The combination of 1-n-butyl-3-methylimidazolium chloride with ZnCl2 affords ionic mixtures with different melting point temperatures depending on the zinc molar fraction. RuCl2(PPh3)3 immobilised in the low melting mixture (60u2009°C) promotes the 1-hexene hydrogenation (turnover frequencies up to 44 min−1) and the recovered solid catalyst phase can be reused several times.