The hydrolysis of bromodifluoromethyltriphenylphosphonium bromide [1]

Hydrolysis of [Ph₃$\text{P}\text{+}$CF₂Br]Br^? afforded a high yield of bromodifluoromethane and triphenylphosphine oxide. Hydrolysis in the presence of a radioactive isotope of bromine or sodium iodide gave unequivocal evidence that the mechanism for this reaction proceeds through a difluorocarbene intermediate.     

The crystal structure of copper bromide telluride

The crystal structure of CuBrTe has been determined. The compound is tetragonal with unit cell dimensions a = 16.417Å, c = 4.711Å, Z = 16, and space group I4₁/amd. Three-dimensional counterdiffraction intensity data (MoKα) were refined with full-matrix least-squares to a conventional unweighted R of 0.066. The structure consists of infinite tellurium spirals with bromine tetrahedra interspersed. Two basic types of disordered copper atoms were found. One type is at the center of the bromine tetrahedra and has several possible locations for each atom. The other type of copper lies on two possible sites in a distorted tetrahedral environment with tellurium and two bromine atoms as nearest neighbors.     

Ion flotation of zinc using ethylhexadecyldimethylammonium bromide

Zinc ions react with the surfactant ethylhexadecyldimethylammonium bromide (EHDABr) to form a surface active sublate which can be removed from aqueous chloride solutions by ion flotation. A typical ion flotation procedure involves passing air through a 235-ml solution containing 5 ppm Zn²⁺, 2.0 M HCl, and 2.5 × 10^?3M EHDABr at a flow rate of 40 ml/min for 150 min. The procedure is simple and rapid. Cadmium, copper, lead, and nickel ions cause reductions of zinc flotation efficiencies of less than 2.5% under the experimental conditions.     

Ion flotation of nickel using ethylhexadecyldimethylammonium bromide

Nickel ions react with the surfactant ethylhexadecyldimethylammonium bromide (EHDABr) to foam a surface-active sublate which can be removed from aqueous chloride solutions by ion flotation. A typical ion-flotation procedure involves passing a fixed volume of air through a 250-ml solution containing 4.0 ppm nickel and 0.05 M KCl at a pH of 5 at a rate of 60 ml/min for 60 min. The method is simple and rapid with 87% removal of the nickel.     

Ion flotation of cadmium using ethylhexadecyldimethylammonium bromide

Cadmium ions react with the collector, ethylhexadecyldimethylammonium bromide (EHDABr), to form a surface-active sublate which can be removed from aqueous bromide

a. Effect of Foreign Metal Ions on the Flotation of Cadmium^a

Foreign ion	Foreign ion concentration (M) (×10?5)	Foreign ion removed (%)	Cadmium removed (%)
None			99.21
Zn2+	6.11	0.06	98.41
Cu2+	6.29	3.64	97.80
Pb2+	3.86	4.80	91.78
Cr6+	7.69	30.75	99.07 solutions by ion flotation. A typical ion flotation procedure involves passing air through a 250-ml solution containing 5 ppm Cd2+, 0.05 M Br?1, and 1.7 × l0?3M EHDABr at a flow rate of 40 ml/min for 1 hr. The procedure was simple and efficient. Chromium, copper, and zinc ions do not interfere under the experimental conditions.

a

Cd²⁺, 4.46 × 10^?5M; EHDABr, 4.25 × 10^?4; Br^?, 5 × 10^?2M; flow rate, 40 ml/min; time, 60 min.

     

Voltammetric behavior of tertiary butyl bromide at mercury electrodes in dimethylformamide

Polarograms for t-butyl bromide in dimethylformamide containing tetramethylammonium perchlorate exhibit two waves which signal stepwise reduction of the starting material to the t-butyl radical and the t-butyl carbanion. Cyclic voltammograms obtained with a hanging mercury drop and at a scan rate of 50 mV s^?1 confirm that the alkyl bromide undergoes stepwise reduction; but the height of the second peak is abnormally small, indicating that t-butyl radicals engage in combination and disproportionation. At a faster scan rate (500 mV s^?1), the first wave nearly merges with the second wave. At all scan rates, two pairs of anodic-cathodic waves, associated with reversible bromide-assisted oxidation of mercury, appear at positive potentials. In addition, another set of anodic-cathodic waves is seen if the potential is scanned rapidly to a value at which the t-butyl carbanion is generated; this set of waves might be related to the formation of trimethylammonium methylide (produced when the tetramethylammonium cation donates a proton to the t-butyl carbanion). Although this latter set of waves is eliminated by addition of a proton donor (diethyl malonate) to the system, the anion of diethyl malonate is itself involved in the appearance of yet another pair of anodic-cathodic waves.     

472—Model reactions of nucleotide sorption: Part I. Interaction between adenine nucleotides and interface in the hydrocarbon-water-cetyltrimethyl ammonium bromide system

A study has been made of the binding between nucleotides (ATP, ADP) and other anions (HP₃O₁₀^4?, HP₂O₇^3?, HPO₄^2?, SO₄^2?) on the interface in the heptane-water-cetyltrimethylammonium bromide (CTAB) system. The binding between anions and their complexes with CTAB on the interface was registered by two methods: by change in interphase tension values and by change in the potential jump on the interface. The energies of binding of the above anions on the interface in the presence of CTAB are determined.The data obtained enabled us to assess the energy of binding of a negative charge with the interface (- ΔG ? 14.6 ± 0.7 kJ/unit charge).A model has been suggested for a study of the behaviour of the interface-CTAB-anion system and the conditions for specific nucleotide binding have been chosen.     

Standard potentials of silver-silver bromide electrode and related thermodynamic quantities in (5, 10 and 15 wt-%) 2-butanol-water mixtures

The standard potentials of silver-silver bromide electrode in 5, 10 and 15 wt.-% 2-butanol have been determined from e.m.f. measurements of a cell of the type: Pt(or Pd), H₂(g)|HBr(m), 2-butanol-water mixtures| AgBr, Ag at temperatures 15°, 25° and 35°C and in the molality range of HBr from 0.003 to 0.1 mol kg^?1. Standard potentials were utilized to calculate: (1) the standard thermodynamic quantities for the cell reaction and for the reaction of HBr formation, (2) the mean activity coefficients of HBr, and (3) the standard thermodynamic quantities for transfer of HBr from water to 2-butanol-water mixtures. The thermodynamic functions for the transfer process have been interpreted in regard to the acid-base properties and structure of the solvents.     

Electrochemical behaviour of triphenylgermanium bromide

The electrochemical behaviour of triphenylgermanium bromide has been thoroughly investigated using various electrochemical techniques including polarography, cyclic voltammetry and controlled potential coulometry. It has been found that in non-aqueous solvents triphenylgermanium bromide gives only one small drawn-out wave, while in aqueous-organic media two reduction waves are observed. The first wave has been ascribed to adsorption of the products of the reduction step II. The triphenylgermanium free radicals have been postulated to combine rapidly with protons in acidic media or to abstract hydrogen from water in alkaline media. The protonated species has been found to be reduced at potentials at which normal reduction of triphenylgermanium bromide takes place giving rise to a superimposed catalytic proton-discharge wave. A mechanism of reduction of triphneylgermanium bromide at the DME has been postulated and analytical methods for the determination of triphenylgermanium compounds at the formulation and trace analysis levels have been developed.     

The predissociations of water ions

Experimental relative abundances of D₂O⁺, OD⁺ and D⁺ ions are given as functions of the initial energy of D₂O⁺ ions in the B?²B₂ state. The D⁺ ions are more abundant than expected on the basis of a recent theoretical model. Less kinetic energy is released in D⁺ formation than in OD⁺ formation, for the same excess energy available. It is suggested that OD⁺ formation should be modelled as a statistical reaction, whereas D⁺ formation is more specific. No detailed model can be suggested on present evidence, but it is pointed out that H₂O⁺ (B?²B₂) can be predissociated to OH⁺ by the X? state to H⁺ by the à state, as well as by repulsive states.     

The magnetic susceptibilities of cobaltocene and chromocene

The magnetic susceptibilities of cobaltocene and chromocene have been measured between 83 and 293 K; for cobaltocene the results suggest an appreciable orthorhombic splitting of the ²∏(σ²πδ⁴ ground state, whilst for chromocene the data provide further support for the ³Δ(σδ³) ground state previously deduced.     

The behaviour of ruthenium anodes in base

Cyclic voltammograms were recorded for ruthenium metal in base as a function of sweep limit and hydroxide ion concentration. A variety of both soluble and insoluble corrosion products were observed and an attempt was made to identify the various processes taking place on the basis of known data for this system. The development of a charge storage film under potential cycling conditions, as on iridium and rhodium, was noted. Current flow under potentiostatic conditions below 2.2 V was attributed largely to metal corrosion, the overpotential for oxygen evolution, which was observed only at higher values, being unusually high under these conditions. The vast difference in corrosion behaviour and rates of oxygen evolution between thermally and anodically prepared ruthenium oxide films was attributed to stronger bonding of surface ruthenium ions in the case of the thermally treated lattice. The pronounced effect of stirring on the anodic reactions of the metal in base was attributed to rapid removal of the weakly adherent surface oxide layer.     

The reaction of diironenneacarbonyl with 1,2-cyclononadiene

1,2-Cyclononadiene reacts with Fe₂ (CO)₉ with dimerization of the allene ligand to give the bis(π-allylene)Fe₂ (CO)₆ complex, which ¹³C and ¹H NMR studies show to be fluxional.     

The self-association of ethanol in non-polar solvents

The self-association of ethanol in solutions of n-hexane, cyclopentane, cyclohexane, carbon tetrachloride and benzene is studied on the basis of heat of dilution data published in the literature. The tetramer formation model fits the experimental data better than other self-association models. The corresponding self-association constants, K_1,4, and heats of reaction, ΔH_1,4, are calculated. The solvent effect is studied using the solvent polarity factor, E_T, and the existence of a linear dependance of log K_1,4 on E_T values is shown.     

The synthesis of some bidentate bismuth-containing ligands

The synthesis and properties including mass spectra of (o-diphenylphosphinophenyl)diphenylbismuthine, o-C₆H₄(PPh₂)(BiPh₂) and (o-diphenylarsinophenyl)-diphenylbismuthine, o-C₆H₄(AsPh₂)(BiPh₂) are described. The failure of attempts to prepare α, ω-bis(disphenylbismuthino)alkanes is discussed.     

The redox properties of organotransition-metal complexes IV. The activation of cyclic polyolefiniron tricarbonyl derivatives by one-electron oxidation

Cyclic polyolefiniron tricarbonyl derivatives [Fe(CO)₂L(C_nH_m)] (L = CO or phosphorus donor) and oxidising agents such as Ag⁺ or [NO]⁺ in CH₂Cl₂ give reactive paramagnetic cations [Fe(CO)₂L(C_nH_m]⁺ which can abstract hydrogen from the solvent to give [Fe(CO)₂L(C_nH_{m + 1})]⁺.     

The reactions of diborane with aryl-organotin compounds

A number of tetraaryltin compounds, Ar₄Sn (where Ar = phenyl, o- and p-tolyl, and p-chlorophenyl) and triphenyltin compounds, Ph₃SnX (where X = Cl, H, OH, OCOCH₃, and OCOCF₃) have been treated with diborane in tetrahydrofuran. Transmetallation occurs in which one or more aryl groups are transferred to boron. The organoboron intermediates give phenols upon oxidation and boronic and borinic acids upon hydrolysis. Pyridine complexes of organoboranes have also been isolated.