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Boron
Terms modified by Boron Selected AbstractsThe Determination of Methanol Using an Electrolytically Fabricated Nickel Microparticle Modified Boron Doped Diamond ElectrodeELECTROANALYSIS, Issue 5 2010Kathryn Abstract A nickel modified boron doped diamond (Ni-BDD) electrode and nickel foil electrode were used in the determination of methanol in alkaline solutions. The Ni-BDD electrode was electrodeposited from a 1,mM Ni(NO3)2 solution (pH,5), followed by repeat cycling in KOH. Subsequent analysis utilised the Ni(OH)2/NiOOH redox couple to electrocatalyse the oxidation of methanol. Methanol was determined to limits of 0.3,mM with a sensitivity of 110,nA/mM at the Ni-BDD electrode. The foil electrode was less sensitive achieving a limit of 1.6,mM and sensitivity of 27,nA/mM. SEM analysis of the electrodes found the Ni-BDD to be modified by a quasi-random microparticle array. [source] The Fabrication and Characterization of a Bismuth Nanoparticle Modified Boron Doped Diamond Electrode and Its Application to the Simultaneous Determination of Cadmium(II) And Lead(II)ELECTROANALYSIS, Issue 16 2008Kathryn Abstract We report the simultaneous electroanalytical determination of Pb2+ and Cd2+ by square-wave anodic stripping voltammetry (SWASV) using a bismuth nanoparticle modified boron doped diamond (Bi-BDD) electrode. Bi deposition was performed in situ with the analytes, from a solution of 0.1,mM Bi(NO3)3 in 0.1,M HClO4 (pH,1.2), and gave detection limits of 1.9,,g L,1 and 2.3,,g L,1 for Pb(II) and Cd(II) respectively. Pb2+ and Cd2+ could not be detected simultaneously at a bare BDD electrode, whilst on a bulk Bi macro electrode (BiBE) the limits of detection for the simultaneous determination of Pb2+ and Cd2+ were ca. ten times higher. [source] Synthesis and Characterization of a New Guanidine,Borane Complex and a Dinuclear Boron(II) Hydride with Bridging Guanidinate LigandsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 28 2007Oxana Ciobanu Abstract We report the synthesis and structural characterization of the new monomeric borane complex H3B·hppH (hppH = 1,3,4,6,7,8-hexahydro-2H -pyrimido[1,2- a]pyrimidine), which represents the first example of a structurally characterized 1:1 complex between hppH and a group 13 element hydride. Significant intramolecular and, in the crystalline phase, intermolecular H···H contacts are established in this complex. It is shown that the complex can be used as a precursor to new dinuclear boron(II) compounds featuring a B,B single bond. Thus H2 elimination followed by dimerization of H3B·hppH leads to [(hpp)BH]2 with two bridging hpp units. The structural details derived from X-ray diffraction measurements are reported.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Boron,Nitrogen Adducts of 1,3,5-Triaza-7-phosphaadamantane (PTA): Synthesis, Reactivity, and Molecular StructureEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 6 2006Brian J. Frost Abstract Addition of BH3 to 1,3,5-triaza-7-phosphaadamantane (PTA) leads to the formation of the first coordination complex of PTA in which a nitrogen and not the phosphorus of PTA is involved in the bonding. Multinuclear NMR spectroscopy, X-ray crystallography, and computational chemistry are utilized in the characterization of the products. Crystal structures of PTA,BH3 (1) and O=PTA,BH3 (2) adducts are described. In addition a coordination polymer, [CpRu(PTA)2Cl(Ph3B3O3)]n (3), resulting from Lewis acid,base adduct formation between the PTA ligands of CpRu(PTA)2Cl and the product of the cyclocondensation of phenylboronic acid is described. The polymeric compound 3 was also characterized by X-ray crystallography. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Boron-Based Diastereomerism and Enantiomerism in Imine Complexes , Determination of the Absolute Configuration at Boron by CD SpectroscopyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 31 2008Manfred Braun Abstract Boron turns out to be a stable stereogenic center in imine complexes of aryl and alkyl boronates. Diastereomerically pure complexes 7a,c are obtained from chiral imine ligands 5a,b that are derived from the amino alcohol (R)- 4. The configuration at the boron atom is determined by crystal structure analyses. Racemic boronates 10a,c, available from a condensation of aryl boronic acids 6 with the achiral imine ligand 9, can be separated into stable enantiomers by HPLC on a chiral column. The racemization barrier ,G, has been determined to amount to 105,115 kJ,mol,1. The comparison of calculated and measured CD spectra permits to assign unambiguously the absolute configuration to boron in the enantiomeric boronate-imine complex 10a.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis, Structure, and Properties of Boron- and Nitrogen-Doped GrapheneADVANCED MATERIALS, Issue 46 2009L. S. Panchakarla Boron- and nitrogen-doped graphenes are are prepared by the arc discharge between carbon electrodes or by the transformation of nanodiamond under appropriate atmospheres. Using a combination of experiment and theories based on first principles, systematic changes in the carrier-concentration and electronic structure of the doped graphenes are demonstrated. Stiffening of the G-band mode and intensification of the defect-related D-band in the Raman spectra are also observed. [source] Elastic constant measurement for standard and photosensitive single mode optical fibresMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 9 2008P. Antunes Abstract In this work we determine the elastic constant, the Young modulus, and the strain limit of commercial optical fibers. The fiber rupture limit in standard and Boron codoped photosensitive optical fibers, usually used in FBG-based sensors, is also quantified. The estimation of such values is extremely relevant, providing useful experimental values to be used in the design and modeling of the sensors. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2467,2469, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23660 [source] Boron doped carbon nanotubes via ceramic catalystsPHYSICA STATUS SOLIDI - RAPID RESEARCH LETTERS, Issue 6 2009Bystrzejewski, Micha Abstract A facile metal catalyst free route to synthesize boron doped (0.6%,1.0%) carbon nanotubes via ceramic nanowires in which the formation of the nanowires (probably serving as templates), the carbon nanotubes and their doping all occur unanimously in the reaction, is presented. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Mobility of boron,polyol complexes in the hemiparasitic association between Rhinanthus minor and Hordeum vulgare: the effects of nitrogen nutritionPHYSIOLOGIA PLANTARUM, Issue 1 2008Fan Jiang Boron (B) is an essential nutrient required for plant growth and physiological processes. Long-distance B transport is facilitated by the formation of B,polyol complexes. We investigated B uptake and distribution in response to differing levels of exogenous nitrogen supply in the hemiparasitic association between Rhinanthus minor and Hordeum vulgare (barley) and in unparasitised barley and single Rhinanthus plants. In this system, the polyol mannitol is the major assimilate in Rhinanthus, whereas polyols are not detectable in barley. Furthermore, previous studies have shown that the accumulation of polyols within Rhinanthus is negatively affected by the application of exogenous nitrogen. Within the association, the strongest accumulation of B was detected in lateral buds and inflorescences of Rhinanthus, consistent with the greatest B demand in strong sink organs supplied through the phloem that contain high concentrations of mannitol. In the host, the strongest B accumulation was found in xylem-supported leaf lamellae. Roots and sheaths did not accumulate substantial amounts of B, while re-circulation of B through the phloem vessels accounted for only 10% (unparasitised) and 8% (parasitised) of the xylem sap-imported B in the mannitol-free barley hosts. In contrast, 53% (attached) and 39% (in the absence of a host) of the xylem sap-imported B was re-circulated in the phloem in the mannitol-rich Rhinanthus. We therefore present the first quantitative uptake and flow models of long-distance B transport in polyol-rich and polyol-free plants. Our findings are consistent with a close relationship between B re-translocation and mannitol concentrations in phloem vessels. [source] A New Approach to the Deposition of Elemental Boron and Boron-Based Coatings by Pulsed Magnetron Sputtering of Loosely Packed Boron Powder TargetsPLASMA PROCESSES AND POLYMERS, Issue S1 2007Martynas Audronis Abstract Large numbers of potential application areas for elemental boron and boron-based thin film materials make this subject area a focus of significant scientific and industrial interest. Applications include thermoelectric energy conversion devices, biomedical implants, metalworking tools and automotive components. Boron is however also recognised widely to be a difficult-to-deposit material. Therefore, a new technique to deposit boron (and other boron-based materials) by pulsed magnetron sputtering of loosely packed powder targets has been proposed. Among the benefits of this approach are: improved stability of the deposition process, increased speed and flexibility of target preparation, enhanced time- and cost-effectiveness and the ability to control readily the target and hence the chemical composition of the coating. [source] Boron(III) Induced Skeletal Rearrangement of Hexaphyrin(1.1.1.1.1.1) to Hexaphyrin(2.1.1.0.1.1),ANGEWANDTE CHEMIE, Issue 25 2010Kohei Moriya ,-System, hab Acht! Die Titelumlagerung liefert das achterförmige Hexaphyrin(2.1.1.0.1.1) (siehe Schema), in dem im Zuge von Redoxreaktionen zwischen 30,- und 28,-Elektronensystemen die BIII -Zentren zwischen trigonaler und tetraedrischer Koordination wechseln. Das Hexaphyrin(2.1.1.0.1.1) kann nach dem Entfernen der BIII -Zentren zwei PdII -Zentren aufnehmen. [source] Boron- and Fluorine-Containing Mesoporous Carbon Nitride Polymers: Metal-Free Catalysts for Cyclohexane Oxidation,ANGEWANDTE CHEMIE, Issue 19 2010Yong Wang Dr. Aufgepeppt mit B und F: Das Titelsystem wurde in einem simplen Einstufenprozess mit 1-Butyl-3-methylimidazoliumtetrafluoroborat als weichem Templat synthetisiert. Die erhaltenen Materialien haben eine ,Morchel-artige" mesoporöse Struktur (siehe Bild) mit schmaler Porengrößenverteilung und guter Photoaktivität unter sichtbarem Licht. Es sind gute Katalysatoren für die selektive Cyclohexanoxidation. [source] Spectroscopy of solar neutrinosASTRONOMISCHE NACHRICHTEN, Issue 5 2010M. Wurm Abstract In the last years, liquid-scintillator detectors have opened a new window for the observation of low-energetic astrophysical neutrino sources. In 2007, the solar neutrino experiment Borexino began its data-taking in the Gran Sasso underground laboratory. High energy resolution and excellent radioactive background conditions in the detector allow the first-time spectroscopic measurement of solar neutrinos in the sub-MeV energy regime. The experimental results of the Beryllium 7 neutrino flux measurements (Arpesella et al. 2008b) as well as the prospects for the detection of solar Boron 8, pep and CNO neutrinos are presented in the context of the currently discussed ambiguities in solar metallicity. In addition, the potential of the future SNO+ and LENA experiments for high-precision solar neutrino spectroscopy will be outlined (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] ChemInform Abstract: Structure and Aromaticity of B6H5+ Cation: A Novel Borhydride System Containing Planar Pentacoordinated BoronCHEMINFORM, Issue 23 2009Hong-Lang Yu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: New Examples of Ternary Rare-Earth Metal Boride Carbides Containing Finite Boron,Carbon Chains: The Crystal and Electronic Structure of RE15B6C20 (RE: Pr, Nd).CHEMINFORM, Issue 47 2008Volodymyr Babizhetskyy Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Structure and Stability of Small Boron and Boron Oxide ClustersCHEMINFORM, Issue 38 2007Michael L. Drummond Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Stability of Lithium in ,-Rhombohedral BoronCHEMINFORM, Issue 47 2006Wataru Hayami Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Palladium-Catalyzed Cross-Coupling Reactions with Zinc, Boron, and Indium Exhibiting High Turnover Numbers (TONs): Use of Bidentate Phosphines and Other Critical Factors in Achieving High TONs.CHEMINFORM, Issue 26 2005Zhihong Huang Abstract For Abstract see ChemInform Abstract in Full Text. [source] Preparation of (E)-1-Alkenylboronic Acid Pinacol Esters via Transfer of Alkenyl Group from Boron to Boron.CHEMINFORM, Issue 1 2005Kazuya Shirakawa Abstract For Abstract see ChemInform Abstract in Full Text. [source] Hepta- and Octacoordinate Boron in Molecular Wheels of Eight- and Nine-Atom Boron Clusters: Observation and Confirmation.CHEMINFORM, Issue 10 2004Hua-Jin Zhai Abstract For Abstract see ChemInform Abstract in Full Text. [source] Titanium(IV) Bromide and Boron(III) Tribromide Promoted Reactions of Arylaldehydes with 3-Butyn-2-one, Methyl Propiolate and Propynenitrile.CHEMINFORM, Issue 10 2003Min Shi Abstract For Abstract see ChemInform Abstract in Full Text. [source] The Ever-Surprising Chemistry of Boron: Enhanced Acidity of Phosphine,BoranesCHEMISTRY - A EUROPEAN JOURNAL, Issue 18 2009Marcela Hurtado Dr. Abstract The acidity-enhancing effect of BH3 in gas-phase phosphine,boranes compared to the corresponding free phosphines is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. Thus, the enhancement of the acidity of protic acids by Lewis acids usually observed in solution is also observed in the gas phase. For example, the gas-phase acidities (GA) of MePH2 and MePH2,BH3 differ by about 118,kJ,mol,1 (see picture). The gas-phase acidity of a series of phosphines and their corresponding phosphine,borane derivatives was measured by FT-ICR techniques. BH3 attachment leads to a substantial increase of the intrinsic acidity of the system (from 80 to 110,kJ,mol,1). This acidity-enhancing effect of BH3 is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. This indicates that the enhancement of the acidity of protic acids by Lewis acids usually observed in solution also occurs in the gas phase. High-level DFT calculations reveal that this acidity enhancement is essentially due to stronger stabilization of the anion with respect to the neutral species on BH3 association, due to a stronger electron donor ability of P in the anion and better dispersion of the negative charge in the system when the BH3 group is present. Our study also shows that deprotonation of ClCH2PH2 and ClCH2PH2,BH3 is followed by chloride departure. For the latter compound deprotonation at the BH3 group is found to be more favorable than PH2 deprotonation, and the subsequent loss of Cl, is kinetically favored with respect to loss of Cl, in a typical SN2 process. Hence, ClCH2PH2,BH3 is the only phosphine,borane adduct included in this study which behaves as a boron acid rather than as a phosphorus acid. [source] Proton- and Redox-Controlled Switching of Photo- and Electrochemiluminescence in Thiophenyl-Substituted Boron,Dipyrromethene DyesCHEMISTRY - A EUROPEAN JOURNAL, Issue 3 2006Holger Röhr Dipl.-Phys. Abstract A luminescent molecular switch in which the active thiol/disulfide switching element is attached to a meso -phenyl-substituted boron,dipyrromethene (BDP) chromophore as the signalling unit is presented. The combination of these two functional units offers great versatility for multimodal switching of luminescence: 1) deprotonation/protonation of the thiol/thiolate moiety allows the highly fluorescent meso - p -thiophenol-BDP and its nonfluorescent thiolate analogue to be chemically and reversibly interconverted, 2) electrochemical oxidation of the monomeric dyes yields the fluorescent disulfide-bridged bichromophoric dimer, also in a fully reversible process, and 3) besides conventional photoexcitation, the well separated redox potentials of the BDP also allow the excited BDP state to be generated electrochemically (i.e., processes 1) and 2) can be employed to control both photo- and electrochemiluminescence (ECL) of the BDP). The paper introduces and characterizes the various states of the switch and discusses the underlying mechanisms. Investigation of the ortho analogue of the dimer provided insight into potential chromophore,chromophore interactions in such bichromophoric architectures in both the ground and the excited state. Comparison of the optical and redox properties of the two disulfide dimers further revealed structural requirements both for redox switches and for ECL-active molecular ensembles. By employing thiol/disulfide switching chemistry and BDP luminescence features, it was possible to create a prototype molecular ensemble that shows both fully reversible proton- and redox-gated electrochemiluminescence. In dieser Arbeit wird ein lumineszierender molekularer Schalter vorgestellt, bei dem das aktive Thiol/Disulfid-Schaltelement an einen meso-phenylsubstituierten Bordipyrromethen (BDP) Farbstoff als Signal gebende Komponente gekoppelt ist. Die Kombination dieser beiden funktionellen Einheiten offeriert eine hohe Vielseitigkeit für das multimodale Schalten der Lumineszenz: 1) die Deprotonierung/Protonierung der Thiol/Thiolat-Gruppe erlaubt es, das stark fluoreszierende meso-p-Thiophenol-BDP und das analoge, nicht fluoreszierende Thiolat chemisch reversibel ineinander zu überführen, 2) die elektrochemische Oxidation der monomeren Farbstoffe ergibt das fluoreszierende, disulfidverbrückte, bichromophore Dimer,dieser Prozess ist ebenfalls vollständig reversibel, und 3) neben der konventionellen Anregung mit Licht erlauben die deutlich getrennten Redoxpotenziale des BDPs ebenfalls eine elektrochemische Generierung des angeregten BDP-Zustandes, d.h., Prozesse 1) und 2) können dazu eingesetzt werden, sowohl die Photo- als auch die Elektrochemilumineszenz (ECL) des BDP zu steuern. Diese Arbeit stellt die Charakteristika der verschiedenen Zustände des Schalters vor und diskutiert die zu Grunde liegenden Mechanismen. Die Untersuchung des ortho-Analogen des Dimers vermittelte zudem Einsicht in mögliche Chromophor,Chromophor-Wechselwirkungen im Grund- wie im angeregten Zustand von solchen bichromophoren Architekturen. Der Vergleich der optischen und Redoxeigenschaften der beiden Disulfid-Dimere gab des Weiteren Aufschluss über strukturelle Voraussetzungen von Redoxschaltern sowie ECL-aktiven molekularen Ensembles. Unter Einsatz schaltbarer Thiol/Disulfid-Chemie und mit den Lumineszenzeigenschaften der BDPs war es möglich, ein erstes molekulares Ensemble zu entwickeln, das vollständig reversible protonen- als auch redoxgesteuerte Elektrochemilumineszenz zeigt. [source] Boron (III) Tribromide or Titanium (IV) Bromide and Lewis Base Promoted Baylis-Hillman ReactionCHINESE JOURNAL OF CHEMISTRY, Issue 3 2002Min Shi Abstract It was found that, when the Baylis-Hillman reaction of arylaldehydes with methyl vinyl ketone was carried out at below -20 °C in the presence of boron (III) tribromide or titanium (IV) bromide using a catalytic amount of Lewis base such as amine, the brominated compounds and the Baylis-Hillman adducts could be obtained as the major products in good yields for various aryl aldehydes. But at room temperature, the elimination products were the major products. In addition, the palladium catalyzed allylic substitution reactions of the elimination products were also examined. [source] Silicon crystal growth from the melt: Analysis from atomic and macro scalesCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4-5 2005K. Kakimoto Abstract The effect of impurity concentration on thermal conductivity of natural and isotope silicon by using equilibrium molecular dynamics simulation is investigated. It was found that the concentrations of the impurities such as boron, phosphor and arsene play an important role in the propagation of phonons in silicon crystals. It was also clarified that a mass difference of impurities and host crystals results in degradation of thermal conductivity of silicon. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Determination of Methanol Using an Electrolytically Fabricated Nickel Microparticle Modified Boron Doped Diamond ElectrodeELECTROANALYSIS, Issue 5 2010Kathryn Abstract A nickel modified boron doped diamond (Ni-BDD) electrode and nickel foil electrode were used in the determination of methanol in alkaline solutions. The Ni-BDD electrode was electrodeposited from a 1,mM Ni(NO3)2 solution (pH,5), followed by repeat cycling in KOH. Subsequent analysis utilised the Ni(OH)2/NiOOH redox couple to electrocatalyse the oxidation of methanol. Methanol was determined to limits of 0.3,mM with a sensitivity of 110,nA/mM at the Ni-BDD electrode. The foil electrode was less sensitive achieving a limit of 1.6,mM and sensitivity of 27,nA/mM. SEM analysis of the electrodes found the Ni-BDD to be modified by a quasi-random microparticle array. [source] Electroanalytical Determination of Cadmium(II) and Lead(II) Using an Antimony Nanoparticle Modified Boron-Doped Diamond ElectrodeELECTROANALYSIS, Issue 10 2009Kathryn Abstract We report the simultaneous electroanalytical determination of Pb2+ and Cd2+ by linear sweep anodic stripping voltammetry (LSASV) using an antimony nanoparticle modified boron doped diamond (Sb-BDD) electrode. Sb deposition was performed in situ with the analytes, from a solution of 1,mg L,1 SbCl3 in 0.1,M HCl (pH,1). Pb2+ inhibited the detection of Cd2+ during simultaneous additions at the bare BDD electrode, whereas in the presence of antimony, both peaks were readily discernable and quantifiable over the linear range 50,500,,g L,1. [source] The Fabrication and Characterization of a Bismuth Nanoparticle Modified Boron Doped Diamond Electrode and Its Application to the Simultaneous Determination of Cadmium(II) And Lead(II)ELECTROANALYSIS, Issue 16 2008Kathryn Abstract We report the simultaneous electroanalytical determination of Pb2+ and Cd2+ by square-wave anodic stripping voltammetry (SWASV) using a bismuth nanoparticle modified boron doped diamond (Bi-BDD) electrode. Bi deposition was performed in situ with the analytes, from a solution of 0.1,mM Bi(NO3)3 in 0.1,M HClO4 (pH,1.2), and gave detection limits of 1.9,,g L,1 and 2.3,,g L,1 for Pb(II) and Cd(II) respectively. Pb2+ and Cd2+ could not be detected simultaneously at a bare BDD electrode, whilst on a bulk Bi macro electrode (BiBE) the limits of detection for the simultaneous determination of Pb2+ and Cd2+ were ca. ten times higher. [source] Electrochemically Initiated Catalytic Oxidation of 5-Thio-2-Nitrobenzoic Acid (TNBA) in the Presence of Thiols at a Boron Doped Diamond Electrode: Implications for Total Thiol DetectionELECTROANALYSIS, Issue 21 2003Olga Nekrassova Abstract The electrochemical response of 5,5-dithiobis(2-nitrobenzoic acid) (DTNB) to increasing additions of thiol species has been examined at a boron doped diamond electrode. A reaction has been shown to occur with a range of biologically relevant thiols and proceeds via a CECC' process. A total thiol detection methodology has been developed showing that the sensitivities of the standard addition plots are independent of the individual thiol species added to the solution. The analytical utility of the reaction process has been assessed using chronoamperometry with the corresponding data producing detection limits of 5.7,,M, 4.4,,M and 5.8,,M for the detection of cysteine, homocysteine and glutathione respectively. [source] The Electrochemical Oxidation of 5-Thio-2-nitrobenzoic acid (TNBA) at a Boron Doped Diamond Electrode: Demonstration of a CEC ReactionELECTROANALYSIS, Issue 19 2003Olga Nekrassova Abstract The oxidation of 5-thio-2-nitrobenzoic acid (TNBA) over a wide pH range has been investigated using cyclic voltammetry at a boron doped diamond electrode. The reaction has been shown to proceed via a CEC reaction process in which at lower pH the thiol moiety of the TNBA species has to undergo deprotonation before oxidation. DIGISIM modelling of the voltammetric profiles deduced a value of 5.2 for the pKa of the thiol moiety which is in good agreement with that obtained from spectrophotometric data. Also reported are the rate constants for all the heterogeneous and homogeneous processes. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||