Mercury Cathode Research Articles

Electrochemical synthesis of phosphine from the lower phosphorus acids

We have studied the reduction of hypophosphorous and phosphorous acids at mercury and lead cathodes and with potassium and sodium amalgams. Both acids are found to be difficult to reduce. With the mercury cathode, the current efficiency for phosphine is within 2.5%. The phosphine yield with the Pb cathode can be raised by adding sulfuric acid or ethylene glycol to the catholyte.

A simple method for forming amorphous rare earth-transition metal alloy nanotube arrays

Arrays of rare earth-transition metal alloy Co 68Nd 32 and Co 96Sm 4 nanotubes, with amorphous structures and outer diameters of ca. 270–330 nm and with lengths of over 30 μm, have been fabricated for the first time by direct current electrodeposition with a mercury cathode via anodic aluminum oxide (AAO) template. The using of mercury cathode is a crucial condition for the growth of nanotubes and the co-reduction of Co 2+, Nd 3+ and Sm 3+ in aqueous solution without any chemical modification of the pores of AAO, since the liquid mercury has characters of excellent conductivity and fluidity, high surface tension, high photoelectric work function, and high over-potential. A possible growth mechanism for the nanotubes is proposed. The as-prepared nanotube arrays display low coercivity and uniaxial magnetic anisotropy, and the easy magnetization direction is perpendicular to the nanotubes axes.

Template electrodeposition to cobalt-based alloys nanotube arrays

Parallel uniform arrays of amorphous ferromagnetic Co 81Ni 19 and Co 37Fe 63 alloy nanotubes with outer diameter around 325–365 nm, wall thickness of 30–60 nm and length of over 40 μm were prepared by a direct current electrodeposition with mercury cathode using porous anodic aluminum oxide membrane as template. The morphology, structure, composition and magnetic property were studied. The results showed that mercury cathode is the key factor to form amorphous alloy nanotubes, and the as-prepared nanotube arrays exhibit obvious uniaxial magnetic anisotropy and the easy magnetization direction is perpendicular to the nanotubes axis. The mechanism of formation of Co based alloy nanotubes was also discussed.

Voltammogram of Dimethyl Analogue of Fuchsone: Simulation

Electrochemical simulation of the cyclic voltammogram of a 2,6-di-methyl-4-(diphenylmethylene)-2,5-cyclohexadien-1-one in DMSO/tetra-n-butylammonium hexafluorophosphate at a mercury cathode was carried out using two shareware simulation programs; CVSIM and ESP 2.4. Two cathodic and two anodic peaks were analyzed.

Electrochemical desulfurization of (1-adamantyl)(alkylsulfonyl)pyridines

The electroreduction of 4-(1-adamantyl)-2-(alkylsulfonyl)pyridines and 2-(1-adamantyl)-4-(tert-butylsulfonyl)pyridine was studied by polarography and preparative electrolysis on the mercury cathode at various compositions of the supporting electrolyte. Under the preparative electrolysis conditions, the CPy-S bond is predominantly cleaved to form the corresponding adamantylpyridines. The conditions for selective electrochemical desulfurization were found.

Special features of the electroreduction of alkyl-(2-pyridyl) sulfones

The electrochemical behavior of methyl- and tert-butyl-(2-pyridyl) sulfones at a mercury cathode is studied in anhydrous dimethylformamide (DMF) and water-organic (DMF, n-aliphatic alcohols) solvents by the methods of polarography and preparative electrolysis. It is found that the presence of a pyridine fragment in sulfones governs the diversity of electrode reactions including those that involve the material of cathode (mercury). The effect of the nature and composition of the organic component of a solvent on the direction of C-S bond cleavage is discussed. The aromatic heterocyclic fragment is selectively splitted out in the electrolysis of sulfone at a glassy-carbon cathode in a 60% EtOH-H2O system containing LiCl, the supporting electrolyte salt.

Cathodic reduction of benzil in acetone and in dichloromethane

The cathodic reduction of benzil has been carried out at a controlled potential on a mercury cathode in two different SSE (solvent-supporting-electrolyte) conditions: (a) acetone/lithium perchlorate in absence of electrophile where 2,3-diphenyl-5-methyl-furan and 1,2-diphenyl-2-hydroxy-1,4-pentanedione were obtained as main products and (b) dichloromethane/tetrabuthylammonium chloride with the addition of oxalyl chloride as electrophile, where a fast electron transfer took place.

Electrochemical behavior of the N-nosyl-protected amino acids in N,N-dimethylformamide

The electrochemical reduction of serine, glycine, and leucine protected by the 4-nitrobenzenesulfonyl group in N,N-dimethylformamide at mercury cathode occurs at two steps. The first one at −0.8 V vs. SCE, after a one-electron transfer, leads the anion radical formation that dimerizes and adsorbs at electrode. In the second step at −1.4 V, an instable dianion forms which then cleaves. The mechanism is discussed.

Separation and quantitation of phospholipid hydroperoxide families using high-performance liquid chromatography with mercury cathode electrochemical detection

High-performance liquid chromatography with mercury cathode electrochemical detection (HPLC–EC(Hg)) was used to separate and quantify various phospholipid hydroperoxide (PLOOH) families. Under the conditions used, baseline separation of four major biologically relevant PLOOH classes was achieved. Responsiveness was linear up to at least 1 nmol of PLOOH with a detection limit in the subpicomolar range (0.1–0.5 pmol). Applying this method to photodynamically stressed murine leukemia cells and mitochondria isolated from these cells, we identified and quantified PLOOHs derived from phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and cardiolipin. In terms of high sensitivity, specificity, and reliability, HPLC–EC(Hg) has a clear advantage over all other existing techniques for determining PLOOHs in complex biological systems.

Screening and Thermal Desorption for Remediation of a Sediment Polluted by the Mercury of a Chlor-Alkaly Plant

Thermal desorption tests were performed on samples taken from a mercury polluted sediment (133 mg/kg) in the vicinity of a chlor-alkali plant that has been operating over a long period using mercury cathodes. After characterization of the sediment, by means of TGA/DTA, SEM, XRD and chemical analysis, the material was screened into various size-fractions. Chemical analysis showed that only the finest size-fractions had a mercury content above the regulatory limit (5 mg/kg) established for areas destined for industrial installations. Thermal desorption tests were applied on the finest size-sediment fractions at furnace temperatures between 300°C and 400°C and solids residence times between 3 minutes and 120 minutes. After 3 minutes at 400°C, the treated sediment residue had a mercury content below the regulatory limit. The short solid residence time and the low desorption temperature required to meet the treatment standards would permit the use of a continuous thermal desorption treatment process in a rotatory dryer, providing that the values of residence times obtained by the lab-scale plant are suitable for a larger scale plant.

Effect of sodium dodecyl sulfate on the rate of hydrogen evolution at a cathode

The effect of H 2 evolution on the mass-transfer coefficient of cathode reduction of potassium ferricyanide at a mercury cathode was studied with the aim of (i) comparing the mass transfer behavior at a Hg cathode with that at solid electrodes under gas-evolving conditions and (ii) testing the effect of anionic surface-active agent on the mass transfer behavior of an H 2-evolving Hg cathode. It is found that the mass transfer coefficient at the Hg cathode was much higher than the value at a solid cathode. The mass transfer coefficient at H 2-evolving Hg was found to decrease in the presence of sodium dodecyl sulfate (SDS) surfactant by an amount ranging from 58.8 to 76%, depending on the H 2 discharge rate and the SDS concentrations.

Enantioselective cathodic reduction of some prochiral ketones in the presence of (−)- N, N′-dimethylquininium tetrafluoroborate at mercury cathode

This work describes preparative scale enantioselective cathodic reduction of some prochiral ketones, viz. 3,4-dihydro-1(2 H)-naphthaleneone, 2-octanone, 1-phenyl-2-propanone, E-3-octen-2-one, 1-octyn-3-one, 1-undecyn-3-one, 1-tetradecyn-3-one at mercury pool in N, N-dimethyl formamide (DMF)–2-propanol (9.5:0.5), using tetrabutylammonium tetrafluoroborate (TBA·BF 4), as supporting electrolyte and (−)- N, N′-dimethylquininium tetrafluoroborate (DMQ·2BF 4), as a enantioselective inductor. The products obtained were corresponding ( S)-alcohols in 24–70% ee.

Catalytic reduction of 1-bromooctane by nickel(I) salen electrogenerated at a mercury cathode in dimethylformamide

Cyclic voltammetry, controlled-potential electrolysis, and double-potential-step chronocoulometry have been used to characterize the catalytic reduction of 1-bromooctane by nickel(I) salen electrogenerated at a mercury cathode in dimethylformamide containing tetramethylammonium tetrafluoroborate. At a hanging mercury drop electrode, nickel(II) salen undergoes a reversible one-electron reduction. In the presence of excess 1-bromooctane, the peak current for reduction of nickel(II) salen is enhanced, whereas no current for oxidation of nickel(I) salen is observed. Controlled-potential electrolyses of solutions containing nickel(II) salen and 1-bromooctane lead to the production of n-octane, 1-octene, n-hexadecane, and di- n-octylmercury. Mechanistically, the formation of the various products involves the intermediacy of n-octyl radicals.

Survey of the electrochemical behavior of chlorinated pyrazines, quinoxalines, and pyridazines at carbon and mercury cathodes

Cyclic voltammetry and controlled-potential electrolysis have been employed to examine the electrochemical behavior of some mono- and dichlorinated pyrazines, quinoxalines, and pyridazines at carbon and mercury cathodes in either acetonitrile or dimethylformamide containing a tetraalkylammonium salt. Unsubstituted pyrazine and pyridazine each exhibit a single reduction wave, whereas unsubstituted quinoxaline shows three cathodic waves. For the chlorinated compounds, an additional wave is seen for the reduction of each carbon–chlorine bond. Depending on the potential of the cathode, bulk electrolyses of dichlorinated pyrazines or quinoxalines afford either the monochlorinated or fully dechlorinated product, whereas the monochlorinated analogues undergo reduction to the dechlorinated species. Electrolyses of chlorinated pyridazines give dark colored solutions, but the products (apparently polymeric) cannot be detected or identified by means of conventional GC, GC–MS, and HPLC techniques.

Cathodically initiated cyclodimerization of trimethyl aconitate

Trimethyl aconitate ( 2) affords, by reduction in dimethylformamide–Et 4NBr at a mercury cathode in 75% yield and high stereoselectivity, pentamethyl-1-(2-methoxy-2-oxoethyl)-1,2,3,4,5-cyclopentane pentacarboxylate ( 6). The product structure, the substoichiometric current consumption and cyclovoltammetry indicate that product formation occurs by means of a base that is electrogenerated from 2. The base induces a catalytic cycle of two successive Michael additions, where 2 acts as an acceptor and its conjugated base 2d as a donor. X-ray structure analysis of the main diastereomer of 6 and quantum chemical calculations show that the most stable out of 16 diastereomers is formed as the main product. This indicates that the cathodically initiated tandem-Michael addition is controlled thermodynamically. In the presence of an excess of dimethyl maleate, 2 undergoes a cathodic heterocoupling to afford hexamethyl cyclopentane hexacarboxylate ( 8).

Convolutive voltammetric studies on some N-benzylsulfonyl-3,5-dimethyl-4- arylazopyrazole and some of its derivatives at a mercury cathode

Convolutive voltammetric studies on some N-benzylsulfonyl-3,5-dimethyl-4- arylazopyrazole and some of its derivatives at a mercury cathode

Electrochemical reduction of halogenated pyrimidines at mercury cathodes in acetonitrile

Cyclic voltammetry and controlled-potential electrolysis have been employed to investigate the reduction of some mono-, di-, tri-, and tetrahalopyrimidines at mercury cathodes in acetonitrile containing tetramethylammonium tetrafluoroborate. Two irreversible cyclic voltammetric waves are observed for reduction of 2-bromo-, 5-bromo-, and 2-chloropyrimidine; the first wave is due to cleavage of the carbonhalogen bond, and the second wave is attributable to reduction of pyrimidine. Cyclic voltammograms for 2,4-dichloro- and 4,6-dichloropyrimidine exhibit three cathodic waves, whereas that for 2,4,6-trichloropyrimidine shows four cathodic waves, arising from sequential cleavage of carbonchlorine bonds as well as the reduction of pyrimidine. For the reduction of 2,4,5,6-tetrachloropyrimidine, a cyclic voltammogram exhibits four major irreversible cathodic waves corresponding to the cleavage of carbonchlorine bonds, but the wave for reduction of pyrimidine is poorly defined. Bulk electrolyses of halopyrimidines at potentials for different stages of reduction lead to products that are consistent with expectations based upon cyclic voltammetry. In addition, our findings agree well with theoretical calculations of the relative stabilities of the various reduction intermediates. Mechanistic aspects of the reduction of halopyrimidines are discussed and, using homogeneous redox catalysis, we have determined the lifetimes of the electrogenerated radical-anions of 2-bromo- and 2-chloropyrimidine.

Selective electrochemical reduction of cinnamyl ethers in the presence of other allylic C[sbnd]O bonds

Several conduritol derivatives protected as allyl and cinnamyl ethers were subjected to electrochemical reduction at a mercury cathode, resulting in selective removal of the cinnamyl group.

Electrochemical Investigation of the Nature of Current Carriers in Sodium Oxyfluoride Glasses

The processes of ion migration in glasses of the NaF–Na2O–B2O3system are studied electrochemically. The results obtained in electrolysis of glass samples in cells with different electrodes are analyzed. The applicability of the known techniques for investigating the nature of current carriers and determining their transport numbers in glasses is discussed. Analysis of the data obtained in electrolysis of the studied glasses in cells with a mercury cathode and anodes prepared from sodium amalgam, metallic silver, and vitreous sodium tetraborate has revealed that protons can participate in the electricity transport processes in addition to sodium and fluorine ions.

Electrochemical Reduction of Phosphor Thio- and Oxotrihalides on a Dropping Mercury Cathode

Electrochemical Reduction of Phosphor Thio- and Oxotrihalides on a Dropping Mercury Cathode