3(2H)-Furanones from mercuric acetate oxidation of allenic ketones. A synthesis of bullatenone

Treatment of allenic ketones $\underset{?}{1}$ with mercuric acetate yields 3(2H)-furanones $\underset{?}{2}$ (90+%). The oxidation of $\underset{?}{1}\underset{?}{c}$ constitutes a new synthesis of bullatenone $(\underset{?}{2}\underset{?}{c})$.     

Double-layer structure and mechanism of electrode reactions: I. Nitromethane reduction on mercury from aqueous solutions

Kinetic measurements of CH₃NO₂ electroreduction in aqueous solutions of pH values ranging from 1 to 9 were carried out with the polarographic technique under different experimental conditions. In particular, different concentrations of the supporting electrolytes NaClO₄ and NaCl, which are nonspecifically adsorbed at the potentials investigated, or else of the specifically adsorbed electrolyte KI, were employed to change the potential _d at the outer Helmholtz plane and/or the charge density q_i at the inner Helmholtz plane. The effects of these changes between pH 4 and 9 are consistent with a rate-determining protonation step $C{H}_{3}N{O}_2^{?}\stackrel{(+H^{+})}{\to }C{H}_{3}N{O}_{2}H$ taking place within the compact layer. As pH is gradually decreased from 4 to 1, double-layer effects are satisfactorily interpreted by assuming that the control of the overall electrode process passes from the above protonation step to the electron-transfer step CH₃NO₂+e→CH₃NO₂^?, again occurring within the compact layer.     

Double-layer structure and mechanism of electrode reactions: Part II. Nitrobenzene reduction on mercury from aqueous solutions

Kinetic measurements of nitrobenzene (RNO₂) electroreduction to phenylhydroxylamine in aqueous solutions of pH ranging from 2 to 12 were carried out with the polarographic technique under different experimental conditions. In particular, different concentrations of non-specifically and specifically adsorbed supporting electrolytes were employed to change the potential φ_d at the outer Helmholtz plane and/or the charge density q_i at the inner Helm-holtz plane. The effects of these changes are amenable to a straightforward interpretation provided the overall electrode process is assumed to be controlled by the electron-transfer step $RN{O}_{2}H\stackrel{+e}{\to }RN{O}_2{H}^{?}$ (step a) for 2<pH<5, by the heterogeneous protonation step $RN{O}_2^{?}\stackrel{+H^{+}}{\to }RN{O}_{2}H$ (step b) for 6<pH<9, by the electron-transfer step $RN{O}_2^{?}\stackrel{+e}{\to }RN{O}_2^{2?}$ (step c) for pH>11, and by both the parallel steps (b) and (c) for 9<pH<11.     

Steroids I. Alkylation of β-ketoesters via their Cu(II) enolates in aqueous media. Application of the synthesis of C-18 functionalized steroids via the torgov approach.

Three steroidal pentaenes ($\underset{?}{8}$a?$\underset{?}{\mathrm{c}}$) have been synthesized, the key step being the alkylation of the Cu(II) chelates to the ring D precursors ($\underset{?}{3}$?$\underset{?}{5}$) by the isothiouronium acetate $\underset{?}{1}$ in aqueous solution.     

Thermodynamic properties of CaTiF5(s)

Calcium titanofluoride CaTiF₅(s) was prepared by solid-state reaction of CaF₂(s) with TiF₃(s) and characterized by X-ray diffraction method. The standard molar isobaric heat capacity $(C_{p\text{,m}}^{\circ })$ of CaTiF₅(s) was determined by a power compensated differential scanning calorimeter in the temperature from 230 K to 710 K. A solid-state galvanic cell with CaF₂ as electrolyte was used to determine the standard molar Gibbs energy of formation $({\mathrm{\Delta }}_{\text{f}}{G}_{\text{m}}^{\circ })$ of CaTiF₅ in the temperature range from 803 K to 1005 K. The galvanic cell can be depicted as:$(-)\text{Pt,}{\text{O}}_2(\text{g,}101.325\text{kPa})/\{\text{CaO(s)}+{\text{CaF}}_2(\text{s})\}//{\text{CaF}}_2//\{{\text{CaTiF}}_5(\text{s})+{\text{CaTiO}}_3(\text{s})\}/{\text{O}}_2(\text{g,}101.325\text{kPa})\text{,Pt}(+)$The second law analysis of present data were carried out to derive the standard entropy $S_{\text{m}}^{\circ }(298.15\text{K})$ and the enthalpy of formation ${\mathrm{\Delta }}_{\text{f}}{H}_{\text{m}}^{\circ }(298.15\text{K})$ and the values derived are 68.7 J · K⁻¹ · mol⁻¹ and −2848.4 kJ · mol⁻¹, respectively.     

Author index

Kinetic measurements of diethylfumarate (DEF) electroreduction to diethylsuccinate in aqueous solutions of pH ranging from 1 to 10 were carried out by the polarographic technique under different experimental conditions, and DEF adsorption was measured by the chronocoulometric technique. The rate changes produced by changes in pH, in buffer concentration, in the potential _d at the outer Helmholtz plane or in the charge density σ_i at the inner Helmholtz plane due to specifically adsorbed iodide ions, were thoroughly examined. The effects of these changes are amenable to a straightforward interpretation if the overall electrode process is assumed to be controlled by an enol-keto transformation of the enol form of diethylsuccinate for 1$R^{?}\stackrel{+H^{+}}{\to }RH$

Synthesis (via reductive elimination or metathesis) and x-ray crystal structure of a tetrameric meso-tin(II) metallocycle Sn(CHSiMe3C6H4︹CHSiMe3−o)2, and characterisation of meso,meso−Sn(CHSiMe3C6H4︹CHSiMe3−o)2

A yellow, diamagnetic tin(II) metallocycle, $meso?S\stackrel{︹}{n(CHSiM{e}_3{C}_6{H}_4}CHSiM{e}_3?o)$ (I) showing a monomeric parent ion in its mass spectrum and a first ionisation energy at 7.6 eV in its photoelectron spectrum, is tetrameric in the solid with an Sn₄ ring (Sn—Sn 2.852(3)Å), as determined by X-ray structure analysis, and was isolated as a minor product on treating SnCl₄ with [{o-C₆H₄ (CHSiMe₃)₂}{Li(tmeda)}₂] (II) at ?78° C (but not +30° C) [tmeda = Me₂NCH₂CH₂NMe₂] in OEt₂. The major product is the spirocyclic complex $S\stackrel{︹}{n(CHSiM{e}_3{C}_6{H}_4}CHSiM{e}_3?o{)}_2$ in which both ligands are in the meso configuration; compound I was more conveniently obtained from II and Sn(OC₆H₂Me-4-Bu^t₂-2,6)₂     

Partial molar volumes of organic solutes in water. XX. Glycine(aq) and l-alanine(aq) at temperatures (298 to 443) K and at pressures up to 30 MPa

Density data for dilute aqueous solutions of two amino acids (glycine, l-alanine) obtained using a flow vibrating-tube densimeter are presented together with partial molar volumes at infinite dilution (standard molar volumes, $V_{\text{m,}2}^{°}$) calculated from the measured data. The experiments were performed at temperatures from (298 up to 443) K at pressures close to the saturation line of water, at pressures in the range from (15 to 17) MPa, and at 30 MPa. Values of an analogue of isothermal compressibility, ${\kappa }_{T\text{,}2}^{°}=-(1/V_{\text{m,}2}^{°})(?V_{\text{m,}2}^{°}/?p{)}_T$, are also evaluated. Maxima on the curves $V_{\text{m,}2}^{°}(T)$ and ${\kappa }_{T\text{,}2}^{°}(T)$ are observed and discussed. The new data along with literature values of standard molar volumes and heat capacities are used for generating the recommended parameterization of an equation of state for standard molar thermodynamic properties of the aqueous amino acids.