Reactions in anhydrous hydrogen fluoride

Symmetrical N-benzyl-substituted hexahydrotriazines(I), benzylamines, benzaldehydes, and diphenylmethanes are synthesized by reacting aromatic compounds with urotropine in anhydrous hydrogen fluoride. A mechanism for the reaction is suggested, and the hypothesis advanced that the primary products of Duff's reaction are type I compounds.For Part I see [1].     

Arsenic pentafluoride equilibria in anhydrous hydrogen fluoride

Earlier work has indicated that arsenic pentafluoride when dissolved in anhydrous HF is present largely as the anion As₂F₁₁^-, particularly temperatures much below ambient. Raman spectra and conductance measurements are used here to show that, at and near room temperature, there are significant concentrations of molecular AsF₅, AsF₆^- and As₂F₁₁^-in equilibrium and that on reduction of temperature, As₂F₁₁^- is formed at the expense of AsF₅ and AsF₆^-. The implications of the Lewis acid and oxidant strengths of AsF₅ are discussed as affecting synthetic procedures in anhydrous HF.     

The autoprotolysis constant of liquid anhydrous hydrogen fluoride

The autoprotolysis constant of HF K: [H⁺][F^?] = 10^?12.50 ( I : 0.1, KSbF₆, 0° C ) has been evaluated from potentiometric titrations of solutions of H⁺ with F^?. The F^? concentrations were determined with the help of an Ag electrode acting in the presence of HCl and AgCl as a F^? electrode.     

Polarographic reduction of cobalt(II) ion in presence of resacetophenoneoxime

Analytical and Bioanalytical Chemistry -     

Polarographic study of the Co(II)-catalyzed reduction of nitrite

In the potential region corresponding to the reduction of Co(OH)⁺ to the metal, a catalytic polarographic current is observed in an ammoniacal buffer solution containing nitrite ion. In neutral unbuffered media, the catalytic current appears even on the limiting plateau of aquacobalt(II) reduction wave. The catalytic current is due to the reoxidation of an electrodeposited metallic cobalt to Co(II) by nitrite ion. The condition necessary for the catalytic reaction to proceed is the increase in pH at the electrode surface. It is shown that the hydroxide ion is produced as a result of the catalytic reaction.     

Oxidation of manganese(II) by ozone and reduction of manganese(III) by hydrogen peroxide in acidic solution

Manganese(II) is oxidized by ozone in acid solution, k=(1.5±0.2)×10³ M⁻¹ s⁻¹ in HClO₄ and k=(1.8±0.2)×10³M⁻¹ s⁻¹ in H₂SO₄. The plausible mechanism is an oxygen atom transfer from O₃ to Mn²⁺ producing the manganyl ion MnO²⁺, which subsequently reacts rapidly with Mn²⁺ to form Mn(III). No free OH radicals are involved in the mechanism. The spectrum of Mn(III) was obtained in the wave length range 200–310 nm. The activation energy for the initial reaction is 39.5 kJ/mol. Manganese(III) is reduced by hydrogen peroxide to Mn(II) with k(Mn(III)+H₂O₂)=2.8×10³M⁻¹ s⁻¹ at pH 0–2. The mechanism of the reaction involving formation of the manganese(II)-superoxide complex and reaction of H₂O₂ with Mn(IV) species formed due to reversible disproportionation of Mn(III), is suggested. © 1998 John Wiley & Sons, Inc. Int J Chem Kinet 30: 207–214, 1998.     

Polarographic reduction of hydrogen ion in non-aqueous solvents

The polarographic reduction of hydrogen ion, furnished by dissociation of a Brønsted acid or present in the undissociated Brønsted acid, is reviewed for the situation where a solvent other than water is involved.     

Solution properties of some pentafluorides and oxide tetrafluorides in anhydrous hydrogen fluoride

Solutions of transition metal pentafluorides, MF₅, M = Nb, Ta, Mo, Re and Os, and oxide tetrafluorides, MOF₄, M = Mo, W and Re, in anhydrous hydrogen fluoride have been prepared. The conductivity and Raman spectrum of the solutions have been recorded. The conductimetric measurements indicate that all the compounds are relatively weak fluoride ion acceptors; the order of Lewis acid strength is OsF₅ > ReF₅ > TaF₅ > MoF₅ > NbF₅ ⪢ ReOF₄ > WOF₄ > MoOF₄. None of the solutions contained sufficient amounts of MF₆⁻ or MOF₅⁻ ions to detect by Raman spectroscopy. The data obtained in this study are discussed, together with similar existing data on other pentafluoride-hydrogen fluoride solutions.     

Polarographic analysis of the reduction waves of Pt(II)-SATSC complex

A polarographic study of the Pt(II)-salicylaldehyde thiosemicarbazone complex in sodium perchlorate as supporting electrolyte is described. In addition to the reduction wave of the complex, a catalytic hydrogen wave is also recorded. The characteristics of this catalytic hydrogen wave are studied under different experimental conditions such as varying acid/complex/supporting electrolyte/surfactant concentrations and also with mercury droptime. Based on these, a probable mechanism for the electrode process has been postulated. Presented at the 12th Annual Symposium in Chemistry held at the Indian Institute of Technology, Madras in March 1987.     

Reactions in anhydrous hydrogen fluoride Communication 5. Fluoroaminomethylation and fluoroacylaminomethylation of haloolefins

Conclusions The new reaction of conjugated fluoroaminomethylation of chloro and fluoro olefins is described; it may be used for the synthesis of various fluorine-containing amines.For Communications 3 and 4 see Zh. Vses. khim. obshch. im. D. I. Mendeleeva11, 354, 356 (1966).This article is published in accordance with a resolution of the conference of editors-in-chief of journals of the Academy of Sciences of the USSR of July 12, 1962, as a dissertation paper by A. V. Podol'skii.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1575–1581, September, 1966.We thank É. I. Fedin and P. V. Petrovskii for determining and interpreting the spectra.     

The anodic oxidation of alkanes in anhydrous hydrogen fluoride and related superacid media

The anodic oxidation of several alkanes in anhydrous hydrogen fluoride at various acidity levels, from “basic” media (KF) to “acid” media (SbF₅) has been studied to establish optimum conditions for the formation of carbenium ions. The oxidation potential of an alkane depends on structure and on the acidity level of the medium. Taking into account thermodynamical data, possible mechanisms for the anodic oxidation are proposed. Furthermore, it is shown that alkanes undergo spontaneous chemical oxidation in acid media (HF + SbF₅ which may be investigated in its kinetic and thermodynamic aspect by means of electroanalytical methods.     

The vibronic and raman spectra of the uranyl ion in anhydrous hydrogen fluoride

The vibronic spectrum of the UO₂²⁺ cation in HF-AsF₅ solution has been recorded in the range 340–450 nm and is much better resolved than corresponding aqueous spectra.