A Liquid-State Tetrafluoroborate Ion-Selective Electrode Based on Brilliant Green Tetrafluoroborate

Abstract

A liquid-state ion-selective electrode which is sensitive to tetrafluoroborate ion, and which is based on Brilliant green tetrafluoroborate, has been developed. A chlorobenzene solution of the basic dye salt is absorbed into natural rubber sheeting which acts as the membrane in the electrode. At concentrations of tetrafluoroborate ion between 10^?4 and 10^?1 M a near Nernstian slope of 58.5 mV per decade change of concentration was obtained at 25°C; the potential response became steady within 1 minute at each concentration. Selectivity constants are given for a range of anions of which only perchlorate interferes markedly (K_{BF 4}-_{/ClO 4}- = 1.0 to 1.6).     

Effect of Lithium Tetrafluoroborate on the Solubility of Carbon Dioxide in the Ionic Liquid 1-Butyl-3-Methylimidazolium Tetrafluoroborate

In this work, the phase behavior of the ternary system of carbon dioxide +1-butyl-3-methylimidazolium tetrafluoroborate?+?lithium tetrafluoroborate has been investigated. Mixtures of known concentrations of the salt, ionic liquid and carbon dioxide were prepared and their bubble point pressures were measured at different temperatures. Results are reported for this ternary system, at carbon dioxide concentrations of 20.2, 27.6 and 35.2?mol-% and salt concentrations of 0.0, 6.0, 11.5, 16.3 and 21.1?mol-% (on a carbon-dioxide free basis) and within temperature and pressure ranges of 293.15?C358.15?K and 1.2?C11.3?MPa, respectively. It was observed that the addition of the salt increased the bubble point pressure and its effect was concentration-dependent, i.e. at higher concentrations of the salt, higher pressures are required. This behavior is greater at higher temperatures.     

Reactions of Methylphenylvinylsulfonium Tetrafluoroborate with Ketone Enolates

The reactions of methylphenylvinylsulfonium tetrafluoroborate (1) with the lithium enolates of 1,3-dicarbonyl compounds, acyclic ketones and cyclic ketones have been studied. Cyclopropanes and cyclic ethers are obtained. The reaction mechanisms are also discussed.     

Reaction of Nitrosonium Tetrafluoroborate with Nitroxyl Radicals

It was established by means of multinuclear magnetic resonance method (¹H, ^{1 3}C, ^{1 9}F and ^{1 4}N) that reaction of 2,2,6,6-tetramethyl-4-R-piperidin-1-oxyl radicals (R = H, OH, OMe, OCOPh, NHCOMe) with nitrosonium tetrafluoroborate gave rise to the corresponding 2,2,6,6-tetramethyl-1-oxo-4-R-piperidinium tetrafluoroborates. Linear correlations were found between the chemical shifts of atoms H⁴, C⁴ of cations and respectively ₁-constants of substituents R and chemical shifts of C⁴ atom calculated from increments of substitution. The conformational features of the generated nitrosonium cations are considered on the grounds of vicinal coupling constants J _{H H} and quantum-chemical calculations by AM1 method.     

Efficient Synthesis of 2,6—Diphenyl—4—arylpyrylium Tetrafluoroborate

Four pyrylium salts,(2,6-diphenyl-4-arylpyrylium tetrafluoroborate,aryl=C6H5,4-MeO C6H4,4-Me2NC6H4,4-NO2C6H4) were synthesized efficiently and economically from acetophenone and substituted chalcones in the presence of borontrifluoride.     

Synthesis of Aryliodides from Diazonium Tetrafluoroborate in Dimethylsulfoxide

One of the best methods for the introduction of iodine in the aromatic ring, is the reaction of arenediazonium salts with iodine ions in water¹, for which a free radical mechanism was proposed². Although the yields are generally good, numerous attempts were made to improve the method and to simplify the isolation procedure.     

Pressure-Induced Solidification of 1-Butyl-3-methylimidazolium Tetrafluoroborate

We have used Raman spectroscopy to investigate the high-pressure phase behavior of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), a representative ionic liquid, at pressures up to ~7.5 GPa. We have also studied how increasing pressure leads to conformational changes in the [bmim]⁺ cation. We have found that liquid [bmim][BF₄] undergoes pressure-induced solidification (freezing) into a superpressed (metastable) state at 2.5 GPa; another structural change probably occurs at ~6 GPa. Remarkably, conformational changes in the [bmim]⁺ cation between trans and gauche conformers are concordant with the metastable structural changes of [bmim][BF₄]. As the pressure is increased from ambient, the fraction of gauche conformers increases, but the gauche fraction decreases above the solidification pressure (2.5 GPa), and slope of the gauche/trans ratio changes again above 6 GPa. We interpret these results in terms of the fragility of the ionic liquid.     

Tetrafluoroborate Selective Electrodes on the Basis of Cations with Delocalized Charge

Screening of active substances based on styryl and trimethine cyanine dyes was carried out to prepare tetrafluoroborate ion‐selective electrodes. Correlations between the nature of the organic cation (pK_a) and working pH ranges of the sensors were studied. New tetrafluoroborate‐selective PVC membrane electrodes based on an active substance formed by the ion pair of 2‐(n‐ethylcarbazol‐3)‐ethenyl‐1,3,3‐trimethyl‐3H‐indolium and 2‐[3‐(5,6‐dimethyl‐3‐nonyl‐1,3‐benzothiazol‐2(3H)‐ylidene)propenyl]‐5,6‐dimethyl‐3‐nonyl‐1,3‐benzothiazolium with tetrafluoroborate ion were developed. The electrodes are non‐sensitive to pH in the range of 2–8 and can be used for boron determination in acidic media of 6–7 mol L^?1 H₂SO₄. The developed sensor was successfully applied for the determination of B₂O₃ in CdS(Se) nanocrystal‐doped glasses.     

Lithium Tetrafluoroborate–Catalyzed Solventless Synthesis of α-Aminonitriles

Summary. Lithium tetrafluoroborate-catalyzed one-pot, highly efficient, and solvent-free protocol has been developed for the synthesis of α-aminonitriles from aldehydes/ketones, amines, and trimethylsilyl cyanide.     

Solid State Dynamics of Tricarbonyl(eta-1,5-cyclohexadienylium)iron Tetrafluoroborate and Tricarbonyl(eta-1,5-cycloheptadienylium)iron Tetrafluoroborate

The dynamic behavior of [(C(6)H(7))Fe(CO)(3)]BF(4) (I) and [(C(7)H(9))Fe(CO)(3)]BF(4) (II) in the solid state has been investigated principally by NMR spectroscopy. High-resolution variable-temperature (1)H and (13)C NMR spectra indicate that both complexes have a solid state phase transition above which there is rapid reorientation of the cyclodienylium rings and fast exchange of the carbonyl groups. The transition occurs between 253 and 263 K for I and between 329 and 341 K for II. The presence of the phase transition is confirmed by differential scanning calorimetry (DSC). (57)Fe M?ssbauer spectroscopy supports the notion that complex I is highly mobile at room temperature, while II is relatively static. The activation energy for the cyclodienylium group rotation in the high-temperature phase of I is estimated from (1)H spin-lattice relaxation time measurements to be 17.5 kJ mol(-)(1). Static (13)C NMR measurements of the solid complexes in the high-temperature phase indicate that the (13)C chemical shift anisotropies are only 20-30 ppm. This is significantly less than that expected to result from motion of individual groups and thus suggests that rotation of the whole molecule is involved. A single-crystal X-ray structural determination of complex II, at 295 K, showed that the complex is tetragonal (space group P4(1), a = 10.610(1) ?, c = 21.761(3) ?, V = 2449.7(5) ?(3), rho(calc) = 1.734 g cm(-)(3)), with eight cycloheptadienyl cations and eight tetrafluoroborate anions per unit cell. In addition, powder X-ray diffraction studies of both I and II confirm that at low temperatures both complexes have a tetragonal unit cell, which transforms to a cubic unit cell above the phase transition. The powder patterns, recorded above the phase transition, support the proposal that the complexes are undergoing whole-molecule tumbling in their dynamic regimes.     

Selective Thioacetalization of Aldehydes Catalyzed by Aqueous Zinc Tetrafluoroborate

Abstract

A wide range of cyclic dithioacetals are prepared from the corresponding aldehydes in the presence of aqueous solution of zinc tetrafluoroborate.     

1-乙基-3-甲基咪唑四氟硼酸盐离子液体的量子化学研究

The results of the quantum chemistry study of the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIM+BF4-) were reported. The ab initio method and density functional theory (B3LYP method) was used to optimize the stable structure of the gas phase ion pair at the level of 6-311++G** basis set, respectively. An IR spectra for EMIM+BF4- were obtained through the vibrational analysis. The changes of atomic charge assignments have been investigated using the Natural Bond Orbital method. The computational results show that there exist hydrogen bonds and other weak interactions between the cation and the anion. Using counterpoise correction method to estimate the basis set superposition error, the interaction energy between the cation and anion is 346.78 kJ/mol.     

Lithium Tetrafluoroborate–Catalyzed Solventless Synthesis of α-Aminonitriles

Lithium tetrafluoroborate-catalyzed one-pot, highly efficient, and solvent-free protocol has been developed for the synthesis of α-aminonitriles from aldehydes/ketones, amines, and trimethylsilyl cyanide.     

On the Problem of the Tetrafluoroborate Ion State in Complexes with Nitrogen-Containing Organic Bases

Using a number of Cu(II), Zn(II), and Cd(II) tetrafluoroborate complexes with nitrogen-containing organic bases as examples, the possible existence of two states of the BF₄ ^– ion, namely, the "half-coordination" and counter-ion states, was studied. It was found that in [ML₂(BF₄)₂] complexes with strong organic bases (L), the "half-coordination" of the anion exists. As the electron-donating ability of the ligand increases, the interaction between the tetrafluoroborate ion and the metal atom becomes more efficient.     

Palladium-Catalyzed Synthesis of Arylamines from Diphenyliodonium Tetrafluoroborate and Secondary Amine

The hetero-cross coupling reaction of diphenyliodonium tetrafluoro-borate with secondary amine in the presence of LiNTMS₂ or NaOtBu as base, Pd₂(dba)_3°CHCl₃ as catalyst, and tri-o-tolylphosphine as ligand afforded arylamines at room temperature under mild conditions.     

铁催化的苯并异吡喃鎓四氟硼酸盐的氧化自由基偶联行为研究

苯并异吡喃鎓四氟硼酸盐是新近发现的一类新型有机盐, 具有对空气和潮气的较高稳定性, 同时保持苯并异吡喃鎓盐的高反应活性. 研究了苯并异吡喃鎓四氟硼酸盐在几种铁盐和铁配合物催化剂存在下与过氧化氢之间的氧化反应行为, 发现了一类具有特色的经高价铁物种催化氧化O-H键引发的自由基双分子偶联反应. 本工作对该反应的条件进行了优化研究, 对反应产物和主要副产物的形成机理进行了探讨.