Mercury Cathode Research Articles

Adsorption and exclusion characteristics of nitrocellulose with reference to a microcolumn clean-up technique for the detectionof propellants traces in firearms discharge residues

A study has been made of the adsorption and exclusion characteristics of nitrocelluloses on 12 representative supports under conditions relevant to the trace analysis of nitrocelluloses by size-exclusion chromatography with amperometric detection at a mercury cathode. It ws found, in particular, that in acetonitrile nitrocelluloses are largely excluded from Porapak T, whereas they are adsorbed onto this support from mixtures of acetonitrile with diethyl ether. This provides the basis of a described microcolumn clean-up technique that enables nanogram amounts of nitrocellulose in contaminated firearms propellants residues to be characterized.

Electrogenerated chemiluminescence on the electrogenerated chemiluminescence (ECL) of tetrakis(pyrophosphito)diplatinate(II), Pt 2(P 2O 5H 2) 44−

The electroreduction of Pt 2(P 2O 5H 2) 4 3− (or A 4−) in MeCN (0.1 M Bu 4NBF 4) at a Pt electrode occurs at potentials where background reduction occurs and results in green light emission characteristic of A 4−3. A reaction mechanism involving electron transfer between A 5− and a reduction product of Bu 4N + is proposed. The emission that occurs at a mercury cathode shows a new band at ≈ 607 nm.

Further developments in the high-precision coulometric titration of uranium

An experimental study of the current efficiency in the coulometric generation of Ti(III), as a function of electrolyte composition, current density and electrode material, has been performed. The cathodes investigated include platinum, mercury and graphite. The first two are suitable for high-precision determination of uranium. The graphite surface is readily poisoned, rendering it useless for high-accuracy work. The use of mercury requires thorough removal of chloride from the system. The precision and error obtained are comparable for both the mercury and platinum cathodes, and are of the order of 50 ppm.

The electroreduction of 2-nitroazobenzene in dimethylformamide

The electroreduction of 2-nitroazobenzene proceeds in three one-electron reversible steps (half-wave potentials −0.93, −1.18 and −1.60 V vs. SSCE) at the mercury cathode in 0.04 M TBAP/DMF. The reduction products of the first two steps undergo a homogeneous disproportionation reaction producing a three-electron product. Two electrons are consumed for the formation of 1,3- dihydroxy-2-phenylbenztriazole. The anodic wave of the reduction product (at −0.6 V) probably corresponds with the third consumed electron. Enhanced water content (0.5 to 1.5 M) of DMF does not influence the reaction pathway substantially. The addition of alkali metal perchlorates (Li or Na > 0.05 M) causes the formation of 2-phenylbenztriazole- N-oxide after the two-electron reduction of 2-nitroazobenzene.

Studies on the mechanism of electroreduction of isonicotinic acid and its carboxylic isomers on mercury cathode

A mercury pool of about 10 cm 2 was used as a cathode and linear potential sweep were used for voltammetric studies of isonicotinic acid and its carboxylic isomers in aqueous solutions. The authors discovered that at every second scanning in isonicotinic acid solution there began to appear a new wave at a half-wave potential more positive than the original one. These new waves seem to be due to a new these intermediates bear a linear relationship with pH, slopes of these straight lines being 55–60 mV pH −1. These active species decayed according to the second order reaction law and the 2 k rate constants have been determined. Also, a coloured substance was observed during the electroreduction of isonicotinic acid. The relationship of the formation of the coloured substance and the simultaneous decay of the active intermediates has been demonstrated. A scheme of the electroreduction is suggested: the first step of the reaction is: ▪ and the succeeding steps are going through the following courses: ▪ Interesting comparisons have been made between the electrochemical reduction processes and the radiation processes of the three pyridine monocarboxylic acids. Similarity and parallelism between these two processes are prevailing.

Dimethylpyrrolidinium, a catalyst for organic electroreductions

The electroreduction of dimethylpyrrolidinium (DMP +) in diglyme on mercury cathodes was investigated. It was found to proceed via a fast one-electron transfer resulting in an insoluble “amalgam”. The DMP + amalgam was reactive and transferred electrons to suitable substrate with regeneration of DMP +. Thus DMP + could be used as a catalyst for electroreduction and this possibility was studied. It was found to be a suitable catalyst for the reduction of several difficult-to-reduce substrates ( E 1/2 < −2.8 V vs. SCE). Among others it effected the reduction of fluorobenzene, an aliphatic chloride, and simple conjugated dienes. A possible mechanism and the utility of the reaction are discussed.

Electrochemical reduction of unsymmetrically substituted diphenyliodonium salts at mercury cathodes in dimethylformamide

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemical reduction of unsymmetrically substituted diphenyliodonium salts at mercury cathodes in dimethylformamideMohammad S. Mubarak and Dennis G. PetersCite this: J. Org. Chem. 1985, 50, 5, 673–677Publication Date (Print):March 1, 1985Publication History Published online1 May 2002Published inissue 1 March 1985https://doi.org/10.1021/jo00205a024RIGHTS & PERMISSIONSArticle Views102Altmetric-Citations21LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (676 KB) Get e-Alerts Get e-Alerts

Electrochemical reduction of phenyl(9-m-carboranyl)iodonium tetrafluoroborate

This paper shows that the controlled-potential electrolysis (-0.4 V, s.c.e.) of phenyl(9-m-carboranyl)iodonium tetrafluoroborate (I) on a mercury cathode in a 0.05 M solution of Bu/sub 4/NBF/sup -//sub 4/ in DMF proceeds regiospecifically with breakage exclusively of the C-I bond in the cation of (I) to give 70% benzene (as indicated in gas-liquid chromatography) and 73% 9-iodo-m-carborane with a current yield of about 80%. These results support a previous hypothesis that all the reactions of phenyl(B-carboranyl)iodonium salts with nucleophiles, which accompany breakage of the C-I bond, proceed by the transfer of one electron from the nucleophile to the iodonium cation.

Preparation electrochimique de sels de tetraalkyldietain

Dichlorotetraalkylditin (R 2ClSn) 2 (R = Me, Et and Bu) was prepared by electrolysis of an acetonitrile solution of dialkyltin dichloride on a mercury cathode. The ditin compounds were precipitated by acetate ions and were isolated in good yields. Their polarograms, which show a very characteristic peak near −0.75 V/SCE, are explained by an E C E mechanism.

Elektrochemische Reduktion von Trichloracetaldehyd‐Olefin‐Additionsprodukten

Electrochemical Reduction of Trichloroacetaldehyde‐Olefin‐Addition‐ProductsTrichloroacetaldehyde reacts with different olefins forming addition products. In most cases this reaction results in 1, 1, 1‐trichloro‐2‐hydroxy compounds (2a–d). But also a different route of reaction is possible. Thus 2, 3‐dimethylbut‐1‐ene (1e) forms 4‐trichloro‐1, 1, 2‐tetrahydroxy‐furane (2e) and cyclohexene (1f) forms 3‐trichloromethyl‐2‐oxabicyclo‐2, 2, 2‐octane (2f).All addition products are suitable starting materials for electrochemical conversions. In acidic electrolytes, on lead cathodes the electrochemical reduction results in a simultaneous cleavage of a CCl and a CO bond to form the CHCCl2‐group (3a‐f). In neutral electrolytes, on mercury cathodes, however, a reductive conversion of a CCl3 – group to a CHCl2‐group takes place (4c, 4f).

Electrochemistry of Biomass-Derived Materials I. Characterization, Practionation, and Reductive Electrolysis of Ethanol-Extracted Explosively-Depressurized Aspen Lignin

Abstract The chemical characterization (functional group distribution) and spectroscopic properties (13C, 1H, IR, UV-Vis) of a number of lignins obtained from ethanol extraction of explosively-decompressed aspen (Populus tremuloides) lignin (EEEDAL) are described. In this process mod is heated to ∼240°C by direct steam and fiberized by sudden decompression. Both mechanical and chemical degradation occur which lead to a decrease of the molecular weight of all of the natural polymers. The lignin fraction is soluble in alcohols; it has a low number average molecular weight (925) and is very reactive. EEEDAL was subjected to fractionation by differential solubility prior to and after electrolyses on mercury cathodes at −2.6 V vs. Ag/AgCl in methanol/tetraethyl-ammonium perchlorate. After recovery of 85–90% of the original weight of material used by precipitation with acid, followed by a series of extractions, the chemical and spectroscopic properties of each fraction were determined. The acid-insoluble fractions are more condensed than the acid-soluble fractions and have lower phenolic OH and lower aliphatic OH contents than the acid-soluble fractions. The acid-soluble fractions phenolic OH content approaches one per phenylpropane (5) unit of the Lignin. Electrolyses increase the amount of lower molecular weight, high phenolic content, acid-soluble lignins and changes the molecular weight distribution by decreasing the polydispersity of the resulting lignins. These low-molecular-weight lignins are chemically reactive (for instance, with formaldehyde) and can be used in the partial replacement of phenol in phenol-formaldehyde thermosetting resins.

Electrochemical reduction of 1,2-vinylene and 1,4-butadienylene bis-phosphonium salts

The electrochemical reduction of 1,2-vinylene and 1,4-butadienylene bis-phosphonium salts has been investigated on a mercury cathode in unbuffured or acidic hydroorganic media. It is controlled by ylid character of the radical obtained after the first electronic transfer. This ylid character induces an heterolytic PC bond breaking with the unsaturated bridge. This result parallels those obtained in the chemical reduction of the same structures and confirms the high fragility of the bridge.

Electrochemical reduction of tertiary nitroalkanes to amines.

Electrochemical reduction of tertiary nitroalkanes, 2-substituted-1, 1-dimethyl-1-nitroethanes (1), was investigated in aqueous buffer solutions. In polarography, 1 with a phenyl group and/or a hydroxyl group at the 2-position showed an ill-defined wave in the weakly acidic and neutral pH region at relatively high negative potentials, in addition to a well-defined wave arising from the reduction of 1 to the corresponding hydroxylamine (2). Controlled potential electrolysis of 1 at the potential of the former wave gave the 1, 1-dimethylethylamines (3) as well as the hydroxylamines 2. The amines 3 are formed exclusively from 2, probably via the O-protonated form. It is suggested that a phenyl group at the 2-position facilitates the reduction of 2 to 3 by enhancing the adsorption of 2 at the mercury cathode and that a hydroxyl group, while it interferes with the adsorption, assists the reduction by intramolecular hydrogen-bonding to stabilize the O-protonated form of 2.

Nickel(II)-cyclam: an extremely selective electrocatalyst for reduction of CO2 in water

Co2is electroreduced efficiently to CO on a mercury cathode, in the presence [NiII(Cyclam)]2+; even in pure water, the selectivity for reduction of CO2vs. that of H2O is huge.

ChemInform Abstract: A NEW SYNTHESIS OF O‐PRENYL PHENOLS

AbstractDas Naphthochromen (I) reagiert mit Phenylthiylradikalen zum Phenylthiochroman (III).

Réduction électrochimique de γ-nitrocétones. Conditions expérimentales d'accès à des dérivés de la pyrroline et de la pyrrolidine

Optimal conditions for electrosynthesis, at a mercury cathode in hydroalcoholic media, of three classes of nitrogen heterocyclic compounds are set up from an exhaustive study of the electrochemical behaviour of γ-nitroketones 1 and their reduction products.Pyrroline-N-oxides 3 are obtained by cyclization of the hydroxylamine when the nitro compounds are reduced at sufficiently low cathodic potentials. Quantitative yields are achieved in the case of tertiary nitro compounds. In other cases (primary and secondary nitro compounds), simultaneous formation of ketone-oximes 6 occurs.According to the nature of the α-substituent of the carbonyl, the other heterocyclic derivatives can be prepared as follows. In the case of a methyl substituent, pyrrolines 4 can be obtained by reduction of nitro compounds 1 or of N-oxyde pyrrolines 3. Pyrrolidines 5 are prepared by reduction of 1, or 3 and 4 in the case of tertiary compounds. In the case of a phenyl substituent, pyrrolines 4 can only be obtained by reduction of compounds 3 arising from a tertiary nitro compound. Pyrrolines 5 are prepared by direct reduction of 1 (primary and secondary nitro compounds) or of 3 and 4 (tertiary nitro compounds).

Electrochemical reduction of 1-iodo-5-decyne and 1-bromo-5-decyne at mercury cathodes in dimethylformamide

Etude du comportement polarographique et des electrolyses a potentiel controle (en presence et en absence de malonate de diethyle) des halogenures du titre

Stereochimie de l'electroreduction de bromocyclopropanes—III. Diastereoselectivite de la reduction electrochimique de gem-dibromocyclopropanes

Cleavage of a single carbon bromine bond occurs in the two electrons reduction of 2,2 disubstituted 1,1 dibromo cyclopropanes. Analysis of the diastereoisomeric mixture of monobromo compounds obtained at the term of electrolysis at a mercury cathode in a hydroethanolic media allows to determine which of the two bromine atoms is preferentially cleaved. ▪ When R 2 = Ph, R 1 = H or CH 3 only a low stereoselectivity is generally observed. Nevertheless, yields up to 84% of the cis isomer are achieved when R 1 = H. Best results are obtained when R 2 is a carboxy group (CO 2H, CO 2Me or CO 2Et) especially when the reduction is carried out in the presence of quaternary ammonium cations. The cis isomer is always preferentially formed; yields up to 92% when R 2 = CO 2H and R 1 = Ph, and up to 99% when R 2 = CO 2Et and R 1 = CH 3 can be achieved. Influence of electrolyses conditions (working potential, nature of the supporting electrolyte) on the stereochemical course of the reduction is investigated.

Facts and Fantasy on Tetrathio Oxalate—Activation and Condensation of Carbon Disulfide

Abstract In its reactions with electron-rich metal centers, including the mercury cathode, CS2 undergoes a wide variety of reactions to produce CnSm groups in varying charges and coordination modes. The coupling of two CS2 molecules to formally give C2S4 group has been shown to produce three different moieties: (a) Coupling via C-S bond formation to produce an MC(:S)SC(:S)S ring. (b) Coupling via C-C bond formation to formally produce ethenetetrathiol. (c) Coupling via electroreductive dimerization to produce stable tetrathio oxalate salts.

Electroinitiated polymerization of some acetylenic derivatives, a polarographic study

AbstractThe polarographic reduction of some acetylenic derivatives—phenylacetylene, diphenyldiacetylene and methyl propiolate, as well as of some quarternary salts (ammonium, phosphonium, arsonium and stibonium), was investigated in order to establish whether the electroinitiated polymerization process took place by direct electron transfer to the acetylenic monomer or indirectly.The half‐wave potentials of the compounds mentioned at the dropping mercury cathode and at the stationary platinum electrode were measured. From the experimental data on the polymerization of the above acetylenic monomers, some statements on the kinetics of the polymerization process were made.