Showing papers on "Supporting electrolyte published in 1977"

A Flow‐Through Porous Electrode Model: Application to Metal‐Ion Removal from Dilute Streams

Abstract: A one-dimensional model for flow-through porous electrodes operating above and below the limiting current of a metal deposition reaction has been developed. The model assumes that there is one primary reactant species in an excess of supporting electrolyte, and that a simultaneous side reaction may occur. The model predicts nonuniform reaction rates due to ohmic, mass-transfer, and heterogeneous kinetic limitations; the effects of axial diffusion and dispersion are included. Results are compared with the experimental data observed by various authors for the deposition of copper from sulfate solutions with the simultaneous generation of dissolved hydrogen. Satisfactory agreement between model predictions and experimental data on over-all reactor performance and deposit distributions has been accomplished. For an upstream counterelectrode, distributions of reaction rate (for both single and multiple reactions), concentration, and potential describe the detailed system behavior.

Linear-sweep Voltammetry and the Simultaneous Determination of Purine Bases and Their Nucleosides in the Glassy Carbon Electrode

Abstract: Adenine, adenosine, guanine, and guanosine were voltammetrically oxidized in a glassy carbon electrode in aqueous solutions, but at different potentials. In general, the nucleosides were oxidized at more positive potentials than their bases. The bases and their nucleosides were strongly adsorbed on the surface of the glassy carbon electrode at the pH values around neutrality, so that the concentration vs. anodic peak current curves were not linear. The adsorption on the electrode was very dependent on the pH, and at pH values below 4 good linear relationships were observed between the anodic peak current and the concentration. The differences between the peak potentials of each of the purine bases and their nucleosides were most pronounced at pH 2–4. Consequently, it was possible to determine simultaneously both in mixtures of the purine bases and their nucleosides by using Britton-Robinson buffer as a supporting electrolyte in the pH range of 2–4. The proposed method is simple and rapid, since no prior t...

Preparation of benzothiazolylsulfenamides

Abstract: Benzothiazolylsulfenamides are prepared in a high yield and substantially without a side reaction, via direct electrolytic oxidation, by cross-coupling (1) 2-mercaptobenzothiazole or dibenzothiazyl disulfide or an alkali metal salt of 2-mercaptobenzothiazole with (2) a primary or secondary amine, in the presence of a solvent selected from a dipolar aprotic solvent, a protic solvent, water and mixtures thereof, as well as a supporting electrolyte having adaptability to the solvent.

Radially Dependent Corrective Warburg Problem for a Rotating Disk

Abstract: The oscillating concentration distribution of a reacting species in excess supporting electrolyte is calculated for a rotating disk system where a step change in the amplitude of the concentration fluctuation at the surface of the disk occurs at an arbitrary distance from the center of the disk. The response of a product species and of the supporting electrolyte to this step change is presented also. 4 figures.

Fluidized-bed electrodes and related apparatus and methods

Abstract: The current-carrying capacity of a fluidized-bed electrode is enhanced by imparting increased velocities to the particles suspended therein while maintaining a relatively low degree of bed expansion or voidage. This is accomplished in one embodiment of the invention by means of pairs of opposing jets of electrolyte impinging against each other so as to effect a highly turbulent motion of the fluidized particles while the net flow velocity of the supporting electrolyte is kept relatively low. In a second preferred embodiment, the electrolyte flow velocity may be as high as desired, but its direction, preferably horizontal, is reversed at frequent intervals. The suspended particles get thereby intermittently packed against and retained by filters at the alternating outlet walls. The alternating packing and expansion result in improved charge and mass transport, and hence in improved electrode performance. The above improvement is especially applicable to fluidized beds of activated carbon particles and of other materials whose specific gravity is not much higher than that of the supporting electrolyte.

Cathodic polymerization of maleic anhydride with N‐methylpyridinium iodide

Abstract: The electrochemical homopolymerization of maleic anhydride was investigated at constant electric current in a divided cell. The polymer yield depended markedly on the quantity of current passed through the solution, polymerization time, and on the nature of supporting electrolytes and solvents. The visible spectra of electrolysed solutions and the IR spectra of poly(maleic anhydride) were measured. The polarographic measurements revealed that N-methylpyridinium iodide, employed as supporting electrolyte for the polymerization of maleic anhydride, was reduced at a smaller cathodic voltage than maleic anhydride. Under the given reaction conditions the electrolytic reduction products of the salt might have initiated the polymerization. An anionic polymerization mechanism is assumed.

Electrochemically initiated polymerization of styrene with tetraalkyl and ‐aryl group VA halide support electrolytes

Abstract: The electrochemically initiated polymerization of styrene in methylene chloride solvent with the use of platinum electrodes and tetraalkyl and -aryl group VA halides (i.e., quaternary ammonium, phosphonium, and arsonium compounds) as electrolyte has been investigated. The order of reactivity of the electrolytes with respect to polymerization rate and initiation efficiency was found to be: arsonium > phosphonium > ammonium. Mechanisms involving the electroreduction of the group VA quaternary halides to species capable of electroinitiating polymerization are postulated. The observed losses in solution conductivities during polymerization with the quaternary phosphonium and arsonium electrolytes indicate possible interaction between the initiating radical-ionic species and the supporting electrolyte. In an attempt to further elucidate the mechanism of initiation in these systems, a separate series of experiments, employing the nonpolymerizing monomer, 1,1-diphenylethylene, has been carried out.

The electro‐initiated cationic polymerization of indene, 2. Kinetics of polymerization

Abstract: The electrolytically initiated anodic polymerization of indene in the solutions of tetraethylammonium hexachloroantimonate and tetrabutylammonium perchlorate in nitrobenzene under constant electric current and constant potential electrolysis conditions was studied. The polymerization was followed either under continuous electrolysis or by addition of the monomer to the pre-electrolysed solution of the salt. The monomer consumption follows the first-order rate-law, log[M]0/[M]t=kt, and the rate constant of the polymerization increases with increasing current level. The polymer formation was greatly affected by the change of the dielectric constant of the medium, the anode material, and the nature of the supporting electrolyte. The mode of initiation process depends upon the type of the salt. Mechanisms for the initiation reaction were elucidated.

Process for the electrochemical dihydrogenation of naphthyl ethers

Abstract: Naphthyl ethers having at least one ether group may be dihydrogenated in an electrochemical manner by electrolysis of the naphthyl ethers in a solvent consisting essentially of an alkanol having from 1 to 3 carbon atoms, optionally in admixture with a small amount of a cosolvent and containing no more than about 5% by volume of water in the presence of at least one supporting electrolyte selected from the group consisting of tetramethylammonium salt Tetraethylammonium salt Tetramethylammonium hydroxide Tetraethylammonium hydroxide Tetramethylphosphonium salt Tetraethylphosphonium salt Tetramethylphosphonium hydroxide and Tetraethylphosphonium hydroxide In a continuous flow cell with separation of the cathode and anode zones, with the use of a solid cathode having a more cathodic hydrogen overvoltage than that of Cu and a usual solid anode, at temperatures of from -20° to +120° C, and at a pH of more than about 8, according to the galvanostatic operation mode. The dihydrogenation of naphthyl-ethers having the ether group in 2-position is preferred since β-tetralones are obtained via the 1,4-, 3,4- and 1,2-dihydroproducts and hydrolysis thereof; tetralones being important starting substances for the synthesis of pharmacologically interesting compounds. The process can be carried out on an industrial scale with high current density and high space-time yields as well as relative low specific energy consumption.

Purification of sodium hydroxide for use as supporting electrolyte in the determination of chromate by normal pulse polarography

Abstract: Recommended Procedure. The acidity of a solution (10 ml), containing 5 -60 gg of Ti(IV) and 2 ml of I M NaC104 solution, is adjusted to pH 1.6 and titanium is then extracted with 5 ml of 2.5.10 -3 M HX in chloroform by shaking for 1 -2min . The organic phase is transferred into a 10-ml volumetric flask. The aqueous phase is shaken again with 4 ml of chloroform, which is than transferred into the same volumetric flask. The extract is diluted to the mark with 267

Electrolytic redn. of naphthyl ethers in alcohol soln. - uses solid electrodes, giving enol ethers useful as pharmaceutical intermediates

Abstract: Process for dihydrogenating naphthyl ethers (I), having >=1 ether gp., comprises electrolysis under galvanostatic conditions of a soln. of (I) in a 1-3C alcohol solvent, contg. is not >5 vol. % water and opt. a small amt. of a cosolvent. A through-flow cell is used with separate cathode and anode compartments and an R4N+ or R4P+ salt or hydroxide (R is CH3 or C2H5) is added as supporting electrolyte. A solid cathode of a material with H2-overvoltage more negative than that of Cu and a conventional solid anode are used. The temp. is -20 to 120 degrees C and the pH >8. The prods. include enol ethers which can be hydrolysed to beta-tetralones which are starting materials for analgetics and for morphine- or steroid-like cpds. The process is applicable to 1-alkoxy and esp. 2-alkoxynaphthalenes and is economic. In an example, 2-methoxynaphthalene was electrolysed in methanol to a mixt. contg. 56.2% 3,4-dihydro- and 25% 1,2-dihydro-2-methoxynaphthalene.

Electrochromic display body

Abstract: PURPOSE:To prevent a change of an electrode in the effective area due to swelling by using an opposite electrode supported by a polymer having a crosslinked structure and to improve a change due to aging and the responding properties by changing the intake of an electrolytic soln. according to the crosslinked structure. CONSTITUTION:A WO3 film is formed on a transparent electrode 12 for display on a glass substrate 11 by vapor deposition. The thickness of the film is about 2,000Angstrom . A space 14 is filled with propylene carbonate solvent contg. lithium borofluoride as a supporting electrolyte. An alumina plate 16 as a white reflecting plate is inserted, and a cell is constructed through a spacer 15 so that the plate faces to an opposite electrode 17. A living tetramer of alpha-methylstryrene is synthesized in THF, and living polystyrene is prepared by the anionic polymn. of styrene using the tetramer as an initiator. After adding a soln. of polymethyl methacrylate in THF to the polystyrene, a polymn. reaction is caused at a low temp., and the reaction product is press-molded to obtain the electrode 17. At this time, an electrode lead 18 made of stainless steel and having a meshed part in the electrode 17 is formed.

Pulse polarographic determination of ytterbium in minerals

Abstract: Differential pulse polarography was used for the quantitative determination of ytterbium(III) in minerals and oxides of other lanthanides. As the reduction occurs at fairly negative potentials and the reduction of hydrogen ions interferes at low pH the number of suitable supporting electrolytes is limited. At pH > 6 hydrolysis effects cause the reduction peak current to decrease as a function of time. Down to 5.10−-8 M ytterbium(III) can be determined in the supporting electrolyte LiCl (0.1 – 1 M) at pH 5. The analysis of ytterbium(III) in commercial samples showed average relative standard deviations which do not exceed 7%.

Semiintegral Electroanalysis in the Absence of Supporting Electrolyte

Abstract: The limiting semiintegral of the current which flows when a stationary electrode is progressively polarized in the presence of electroactive species has been investigated under the condition of no supporting electrolyte present in the solution. The semiintegral, m(t), of the current, i(t), is defined by m(t)=\fracd^-1/2dt^-1/2i(t)=\frac1π^1/2∫_0^t\fraci(λ)(t-λ)^1/2dλ. The electroreduction of a number of heavy metal ions has been studied at a mercury drop electrode and it was found that the limiting semiintegral is larger than that observed with excess supporting electrolyte present. The finding is in agreement with a simple theory which considers both diffusion and migration mass transfer processes. The factor by which the limiting semiintegral increases has been shown to depend on the diffusion coefficients and charge numbers of the cation and anion.

Electrolytic reduction of isoprenoids. Electrolysis of axerophthene, 15-D-axerophthene, and 7,7′-dihydro-Β-carotene

Abstract: To find the structure of the electrolysis products, we carried out a preparative reduction of ~-carotene (I) in an electrolyzer with a diaphragm, on a mercury cathode, in a supporting electrolyte of Bu4NCIO~ solution in a 2:1 DMF--benzene mixture containing different amounts of PD~ During the electrolysis of I, at a potential of --175 V with reference to a saturated calomel electrode (sce) (corresponding to the formation of a two-electron wave on the polarogram of I), with the addition of a double amount of phenol taken as PD, the starting material gradually disappeared (control by polarographic and spectroscopic methods), At the same time, a product was formed characterized by absorption bands in the electron spectrum with %max = 382, 403, 427 nm, which was reduced in the more highly positive region of the potentials (the E,/2 shift with reference to I was ~-02V) The reaction mixture was then treated as usual to obtain crystalline 7,7'-dihydro-B-carotene (II) in a good yield; its structure was confirmed by electron and mass spectra