Electrochemical oxidation of dibenzothiophene compounds on BDD electrode in acetonitrile-water medium

The electrochemical oxidation of dibenzothiophene and two derivatives, namely 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene, was investigated either separately or as a mixture, on a BDD anode in a miscible acetonitrile (87.5% v/v)-water (12.5% v/v, 0.01 M NaNO3) solution. Linear sweep voltammetry, cyclic voltammetry, chronoamperometry and bulk electrolysis under potentiostatic conditions suggested the probable occurrence of two pathways: direct electrochemical oxidation and indirect reaction with hydroxyl radicals and other reactive oxygen species formed at the BDD anode surface during water discharge. The products extracted upon electrolysis at 1.5 and 2.0 V vs. SCE were analyzed by Fourier-transform infrared spectroscopy, gas chromatography-mass spectrometry and ultra-high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF-MS). The main molecules identified were the corresponding sulfoxides or sulfones, depending on the applied anodic potential. Possible oxidation routes for the dibenzothiophene compounds are proposed

Motivación de las vocaciones científicas en microbiología en alumnos de educación infantil y primaria

Resumen del poster presentado en: XXIX Congreso de la Sociedad Española de Microbiología SEM. Microorganismos: un universo en continua evolucion. Burgos, España. 25-28 junio (2023)Proyectos PID2021-123164OB-I00, EMERGIA20_00114, TED2021-129599B-I00. Agradecemos a Vanesa Rodríguez Valero, Daniel Sánchez Hernández y Rocío Quero García, docentes del C.E.I.P. José Hurtado, Granada

Study of the electrochemical oxidation of 4,6-dimethyldibenzothiophene on a BDD electrode employing different techniques

The electrochemical oxidation of 4,6-dimethyldibenzothiophene (4,6-DMDBT) at low concentrations on a BDD anode was investigated in a monophasic acetonitrile (93.5% v/v)-water (6.5% v/v, 0.01 M LiClO4) solution. Two oxidation steps related to the sequential formation of sulfoxide and sulfone derivatives were identified. Kinetic parameters such as the electron transfer coefficient α, the number of electrons nα involved in the rate-determining step, the total number of electrons n, the reaction rate constant k0 and the diffusion coefficient D of 4,6-DMDBT for the first transformation were determined by cyclic voltammetry, differential pulse voltammetry (DPV), square wave voltammetry and bulk electrolysis under potentiostatic conditions. The process was bielectronic with α = 0.57, nα = 1, k0 = 7.46 × 10−6 cm s−1 and D = 2.30 × 10−6 cm2 s−1. DPV was the most sensitive electroanalytical technique. Using 27 mg L−1 of 4,6-DMTDB, DPV allowed determining a conversión of 91% to sulfoxide after 60 min of electrolysis in a BDD/BDD cell at an anodic potential of 1.50 V, with an apparent rate constant of 0.034 min−1. The electrochemical characterization was corroborated via gas chromatography-mass spectrometry and ultra-high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry, confirming the formation of the sulfoxide in the first step and the sulfone in the second one as main products, alongside a minor proportion of dimers

Electrochemical oxidation of meglumine in a pharmaceutical formulation using a nanocomposite anode

The electrocatalytic oxidation of meglumine and gadoterate meglumine (Gd-DOTA) on a TiO2-Ni(SO4)0.3(OH)1.4 composite anode was investigated in alkaline medium (5 M KOH) using cyclic voltammetry and chronoamperometry. The composite was prepared by hydrothermal method and the morphology and structure of the produced nanoparticles were studied by scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction, atomic force microscopy, BET surface area analysis and Fourier transform infrared spectroscopy. The characterization revealed the formation of Ni(SO4)0.3(OH)1.4 nanobelts dispersed on TiO2 nanoaggregates. The composite was coated onto a porous graphite rod, showing good adherence without requiring any binder (according to their anodic and cathodic charges). The supported composite was electrocatalytic, allowing the oxidation of meglumine, either as pure reagent or contained in gadoterate meglumine solutions. Electrochemical methods allowed determining the kinetic parameters, such as the electron transfer coefficient α, the total number of electrons n and the standard heterogeneous rate constant k0 for the reaction of meglumine. The chronoamperometric tests informed about the good stability of the composite anode upon meglumine oxidation at +0.6 V for 10 h. The electrochemical oxidation of meglumine in a commercial pharmaceutical formulation (Dotarem®) was corroborated via ultra-high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry

Electrochemical oxidation of dibenzothiophene compounds on BDD electrode in acetonitrile-water medium

The electrochemical oxidation of dibenzothiophene and two derivatives, namely 4-methyldibenzothiophene and 4,6-dimethyldibenzothiophene, was investigated either separately or as a mixture, on a BDD anode in a miscible acetonitrile (87.5% v/v)-water (12.5% v/v, 0.01 M NaNO3) solution. Linear sweep voltammetry, cyclic voltammetry, chronoamperometry and bulk electrolysis under potentiostatic conditions suggested the probable occurrence of two pathways: direct electrochemical oxidation and indirect reaction with hydroxyl radicals and other reactive oxygen species formed at the BDD anode surface during water discharge. The products extracted upon electrolysis at 1.5 and 2.0 V vs. SCE were analyzed by Fourier-transform infrared spectroscopy, gas chromatography-mass spectrometry and ultra-high performance liquid chromatography coupled to electrospray ionization and quadrupole time-of-flight mass spectrometry (UHPLC-ESI-Q-TOF-MS). The main molecules identified were the corresponding sulfoxides or sulfones, depending on the applied anodic potential. Possible oxidation routes for the dibenzothiophene compounds are proposed