Thermodynamic and transport properties of binary liquid acid—base mixtures. Part 1

Densities and viscosities were determined at five different temperatures for the systems quinoline (Q) with: phenol (P); ortho-chlorophenol (CP); and meta-cresol (MC). From the experimental results the excess volumes, excess viscosities, partial molar excess volumes and the partial molar volumes were calculated. From the dependency of viscosity on temperature, the thermodynamic parameters of activation of flow were also calculated and these results were discussed in terms of the type of interaction between the two components in solution.     

Transport of alkali metal cations across liquid membranes by crown ether carboxylic acids

Competitive alkali metal transport from an alkaline aqueous source phase through a chloroform phase to an acidic aqueous receiving phase facilitated by nine crown ethers with pendant carboxylic acid groups has been investigated. Transport selectivity is controlled by the size of the polyether cavity of the carrier. Increasing the lipophilicity of the carrier, while maintaining a constant polyether cavity size, enhances the total transport rate but does not affect the selectivity. There is poor agreement between the results of competitive transport and the behavior anticipated on the basis of single cation transport studies.     

Synthesis and properties of monocyclopentadienyltitanium compounds

The pentacoordinated complexes (RCp)TiCl₂(acac) (R = H, Me, Ph₂CH) have been prepared by photolysis of (RCp)₂TiCl₂ and acetylacetone in THF and the hexacoordinated compounds (RCp)TiCl(acac)₂ by the reaction of (RCp)₂TiCl₂ and acetylacetone in the presence of triethylamine in isobutyronitrile. The hexacoordinated complexes (RCp)TiCl(oq)₂ (R = H, Me, Ph₂CH; oq = 8-oxyquinolate) have been prepared by the direct interaction of (RCp)₂TiCl₂ and 8-hydroxyquinoline in isobutyronitrile; these compounds can be obtained more quickly by photolysis of the same starting materials in THF solution.     

Synthesis and properties of alkyldicyclopentadienyl-vanadium(III) compounds

The compounds Cp₂VR (R = CH₃, C₂H₅, n-C₃H₇, n-C₄H₉, n-C₅H₁₁, CH₂C(CH₃)₃ or CH₂Si(CH₃)₃) have been prepared from Cp₂ VCl and RMgX in n-pentane. The air-sensitive compounds are stable at room temperature, but decompose between 65 and 138°C. The thermal stability decreases in the order R = CH₃ CH₂Si(CH₃)₃ > C₂H₅ > CH₂C(CH₃)₃ > n-C₅H₁₁ > n-C₄H₉ > n-C₃H₇. Compounds with R = i-C₃H₇ or t-C₄H₉ could not be obtained.     

The acceleration of the hydrogen evolution reaction from acid solutions by sulfur compounds: Part II. Indium amalgam electrodes

Thiourea and its N-substituted derivatives accelerate the hydrogen evolution reaction at mercury, indium and indium amalgam electrodes. The differences in the effects observed with mercury and with indium amalgam electrodes can be accounted for in terms of differences in the adsorption of the organic compounds at the metal-solution interfaces.     

Bilayer-coated capsule membranes. IV. : Control of NaCl permeability by phase transition of synthetic bilayer coatings,depending on their hydrophilic head groups

Ultrathin nylon capsule membranes coated with synthetic bilayers, the hydrophilic head groups of which had cationic, anionic, zwitterionic and nonionic charges, were prepared. Permeation of NaCl trapped in the inner aqueous phase was reduced by a factor of 10-1000 relative to that of the uncoated, semipermeable capsules, and drastically changed at the phase transition temperature, T_c, of the coating bilayers, depending on the charge of their hydrophilic head group. In the case of capsules coated with positively or negatively charged bilayers, NaCl permeation was enhanced at temperatures above the T_c of the coating bilayers, as expected. On the other hand, NaCl release of capsules coated with neutral charged (nonionic and zwitterionic) bilayers was largely reduced at temperatures above the T_c. From activation energy data of Arrhenius plots, the permeation mechanism of NaCl, depending on the membrane surface charge, below and above the T_c was discussed.     

Separation of metals by liquid surfactant membranes containing crown ether carboxylic acids

A water-in-oil-in-water emulsion liquid membrane system is used to transport alkali metal and alkaline earth cations from an external alkaline aqueous source phase through an organic membrane containing a crown ether carboxylic acid and into the internal acidic aqueous phase of the emulsion droplet. The influence of varying the crown ether carboxylic acid structure upon the selectivity and efficiency of competitive metal ion transport is examined.     

Transport of organic acids through perfluorosulfonate polymeric membranes

Carboxylic acids in aqueous solutions permeate through perfluorosulfonate merebranes. The permeation is significantly enhanced when the sulfonic acid groups are convetted to their sodium salt form. Transport fluxes at atmospheric pressure have been found to vary in the 10^-9—10^-6 mol/cm²-sec range, depending on the nature of the acids. Interesting separation possibilities of carboxylic acids from one another or from nonpolar compounds are discussed.     

Organoboron compounds XIII. Preparation and properties of some 2-substituted 1,3,2-dithiaborinans

The preparation and properties of some boron heterocycles of the general formula

(where X = Ph, SR, NR₂, NHR and NHNPh) are described and the general features of their mass spectra discussed.     

Water in polymer membranes. Part III : Water sorption and pore volume in cellulose acetate films

Changes in waveguide properties of several cellulose acetate membranes and one polyimide membrane were measured as a function of their exposure to varying levels of relative humidity. The volume fraction of water in the films and the occupied pore volumes were determined from refractive index and thickness changes. The dependence of the refractive index on water absorption is related to a competition between two processes: one of filling pores with no film expansion and one of “free expansion” where the film expands to completely accommodate the added water volume. The term “pore” is taken to mean a volume with molecular and not macroscopic dimensions. The hydration properties of these dense cellulose acetate membranes were affected by degree of acetylation, casting temperatures and annealing treatments. Annealing CA398 membranes at 180°C decreased film water concentration by reducing the amount of free expansion. Annealed CA398 membranes that were tested in a reverse osmosis cell were found to have high salt rejection compared to unannealed films. The hydration characteristics of a polyimide membrane are compared to cellulose acetate membranes.     

Reduction of dicarbonyl compounds on a DME: Part VI. A comparative study of the electrochemical behaviour of aromatic dicarbonyl compounds

Polarographic and voltammetric studies have been carried out on the reduction of benzyl and acetylbenzoyl in a basic medium.The effect of pH, reactant concentration, drop time and ethanol content on the polarographic and kinetic parameters is shown. The occurrence of adsorption phenomena is inferred from C - E curves. The degree of adsorption decreases as the ethanol content increases. Tafel slopes and reaction orders have been obtained at potentials corresponding to the foot of the wave. On the basis of these experimental data, reduction mechanisms are proposed in the zone where Tafel's law is obeyed.The results obtained here and those corresponding to the acidic medium, together with those concerning phenylglyoxal and phenylglyoxylic acid reported in the literature, are thoroughly discussed. A parallelism in the electrochemical behaviour of these compounds is made evident.     

Synthesis of new layered-type and new mixed-layered-type bismuth compounds

Four new compounds, PbBi₂TiTaO₈F, PbBi₂TiNbO₈F, Bi₅Ti₂WO₁₄F, and Bi₇Ti₅O₂₀F, were prepared and identified by X-ray diffraction analysis. Two of them are new members of a family called layered bismuth compounds. The other two are new members of a family called mixed-layered bismuth compounds. Thermal properties of the new compounds were studied. Moreover, the possibility of the existence of other new members belonging to the family called mixed-layered bismuth compounds is discussed.     

Electrokinetic phenomena in porous membranes: Determination of phenomenological coefficients and transport numbers

Electrokinetic phenomena in porous membranes were studied in the framework of the linear thermodynamics of irreversible processes. Phenomenological coefficients of two commercial porous membranes were determined. The variation of these coefficients with the different concentrations of NaCl used was also studied. Onsager's reciprocal relationship between cross-coefficients holds within the limits of experimental error.Membrane potentials were measured at concentrations ranging from 10^?3M to 75 X 10^?3M. The apparent transport number of the cation,

, was calculated from the diffusion potential expression. An electrometric method was used to obtain the true cation transport number,

, and the water transport number,

, for different solution concentrations, ranging from 15 x 10^?3M to 75 x 10^?3M. The true transport number of the cation,

, was also determined, taking into account water transport across the membrane. A good agreement was found between

and

values.     

Polymerization by alkaline earth metal compounds—I. Studies on the polymerization of methylmethacrylate by triphenylmethyl metal derivatives and related compounds of calcium,strontium and barium

A series of related organo-alkaline earth metal compounds of formula (Ph₃C)MX(THF)_η, (M = Ca, Sr, Ba; X = Cl: M = Ca, Sr; X = Br: M = Ba; X = CPh₃), has been isolated and characterized using analytical and spectroscopic techniques. The polymerization of methylmethacrylate (MMA) has been studied using these organometallic compounds as initiators. Investigations of the tacticity variations of polymethylmethacrylate (PMMA) produced in 1,2-dimethoxyethane or tetrahydrofuran (THF) at 210 K have shown that the syndiotacticity is higher in the former solvent, decreases with the following changes in initiator composition: Ca > Sr ? Ba; Cl > Br; in THF, it is dependent on the monomer concentration. The molecular weight distributions of the PMMA samples are broad and have distinct bi- or poly-modal features. The polymerization process appears to be anionic in nature but the evidence suggests that more than one type of propagation occurs and mechanistic aspects are discussed. Polymerization of bulk MMA by these same initiators is also reported. The initiators RMX(THF)_n (M = Sr, R = Me, n = 3 or R = Et, n = 2) and (C₃H₅)SrBr(THF)₂ are shown to be inefficient for polymerization of MMA. The glass transition temperatures of a range of PMMA samples of differing tacticity are presented and discussed.     

Electron transport and magnetic properties of some mixed-valent alkalithiocuprates

Electrical transport properties of some two-dimensional isostructural compounds KCu₄S₃, RbCu₄S₃, and CsCu₄S₃ and a one dimensional conductor Na₃Cu₄S₄ have been investigated. Conductivities have been measured on pelletized materials in the temperature range 300 to 150 K. All of them behave as metallic conductors. The room temperature conductivities of these compounds are KCu₄S₃, 1600 Ω^?1 cm^?1; RbCu₄S₃, 1400 Ω^?1 cm^?1; CsCu₄S₃, 1250 Ω^?1 cm^?1; Na₃Cu₄S₄, 700 Ω^?1 cm^?1. The observed trend in conductivities among the isostructural compounds may be rationalized either on the basis of shortest CuCu distances or on the carrier charge concentrations per unit volume. All of these compounds behave as Pauli paramagnetic materials.     

Electrocatalysis by ad-atoms: Part VIII. Ag,Pb, Te and Tl ad-atoms for ethylene reduction

As already reported, ethylene reduction at a Pt electrode can be enhanced by ad-atoms of Cu and Hg. Another series of ad-atom species is reported, that is, Ag, Pb, Tl and Te, in which the enhancement order depends on the number of Pt sites occupied by an ad-atom. S_M. This effect originates from the difference between S_M and the number of Pt sites occupied by an ethylene molecule, which causes an increase in the number of Pt sites available for hydrogen adsorption. This increase results in the enhancement, in the order Ag>PbTl; Te which has the same S as ethylene has no enhancement effect.For the complete understanding of the function of the mixed surface in the electrocatalysis, a new concept, “catalytic domains”, parts of the mixed surface effective for the electrocatalysis, is introduced, on the assumption that the reaction rate is much higher than the rate of surface migration of the adsorbed species. Then the number of Pt sites which belong to the catalytic domain is calculated. Another concept, “reaction unit mesh”, is also introduced.     

The thermal properties of inorganic compounds: II. Evolved gas studies of some mercury(I) and (II) compounds

The combined thermal analysis techniques of thermogravimetry, evolved gas analysis and mass spectrometry were used to investigate the thermal decomposition of several selected mercury(I), (II) compounds. Although TG curves are presented, the analysis of the evolved gases formed during the thermal decomposition processes was of greater interest. Gaseous products detected included: HgSO₄SO, SO₂ and O₂; Hg(SCN)₂CS₂, (CN)₂ and N₂; Hg(NO₃)₂NO, N₂O, NO₂ and O₂; HgNO₃ H₂ONO, NO₂ and N₂O; and Hg(C₂H₃O₂)₂—organic fragments. The evolved gas analysis was complicated by sublimation of the compounds at low pressures.     

Analytical properties of the amidoxime group: Part VI. Electroanalytical behaviour of ethanediamidoxime

The electroanalytical behaviour of ethanediamidoxime (EDA) has been studied at 0.1 mol l^?1 ionic strength and several pH values (1.75–8.62), using several techniques (dc and DP polarography, chronocoulometry, dc and DP cyclic voltammetry). EDA undergoes an irreversible diffusion-controlled reduction in the entire pH range considered. The best conditions for identification and determination of EDA with the techniques mentioned are also studied.