Oxidation Of Tartaric Acid Research Articles

Controlled oxygen vacancies of ZnFe2O4 with superior gas sensing properties prepared via a facile one-step self-catalyzed treatment

It is widely accepted that oxygen vacancies play an important role in high-performance gas sensors. Unfortunately, the mechanisms responsible for improved gas sensing performance due to oxygen vacancies are not yet well understood because the formation of oxygen vacancy-rich sensors is always accompanied by other variations, especially changes in chemical composition, particle size, and surface morphology. In this work, ZnFe2O4 with controllable oxygen vacancies was prepared by a facile one-step self-catalyzed treatment, “shake and heat”, in which commercial ZnFe2O4 served as the raw material and catalyst for tartaric acid oxidation. Compared to commercial ZnFe2O4, the as-prepared ZnFe2O4 had a similar crystal structure, particle size and morphology but possessed controllable oxygen vacancies, which was validated by XRD, SEM and XPS. The as-prepared oxygen vacancy-rich ZnFe2O4 showed superior performance in sensing acetone compared to the raw materials, i.e., commercial ZnFe2O4. It is proposed that the sensing properties improved because the oxygen vacancies narrowed the band gap and adsorbed more oxygen. This work proves that oxygen vacancies can indeed improve the sensing properties alone and demonstrate a new facile synthesis strategy for oxygen vacancy-rich sensors.

Enhanced photocatalytic performance of Bi4Ti3O12 nanosheets synthesized by a self-catalyzed fast reaction process

Single-crystalline Bi4Ti3O12 nanosheets with the exposed {001} facets have been successfully prepared using a novel self-catalyzed reaction route, which involves a fast reaction of Bi2O3 and TiO2 at 280 °C with the critical assistance of tartaric acid. It is believed that the formation of Bi4Ti3O12 nanosheets is driven by the massive heat released during the oxidation of tartaric acid when Bi2O3 and TiO2 are mixed. With this simplified novel process, the synthesis of high quality Bi4Ti3O12 photocatalyst can be accomplished at low temperatures of 280 °C in less than 10 min. The as-obtained optimum nanosheet photocatalyst exhibits high visible light photodegradation of methyl orange, indicated by the 3.92 times higher efficiency than that of the Bi4Ti3O12 nanosheets prepared by a widely acknowledged molten salt method. In addition, this Bi4Ti3O12 nanosheet photocatalyst presents high recycling ability and storage stability. The X-ray photoelectron spectrometer and electron paramagnetic resonance analyses reveal that oxygen vacancies are produced on the surface of as-prepared Bi4Ti3O12 nanosheets after the self-catalyzed reaction, which then extend the valence band width and reduce the band gap of the Bi4Ti3O12 photocatalyst. It is therefore concluded that the much enhanced photocatalytic activity of the as-prepared catalyst is the synergistic effects of the valence band widening that increases the separation efficiency of the photo-generated carriers and the band gap narrowing that broadens the absorption edge of light.

Voltammetric determination of tartaric acid in wines by electrocatalytic oxidation on a cobalt(II)-phthalocyanine-modified electrode associated with multiway calibration

The electrocatalytic oxidation of tartaric acid on a carbon paste electrode modified with cobalt (II)-phthalocyanine was demonstrated and applied to the development of a highly sensitive, simple, fast and inexpensive voltammetric sensor to determine tartaric acid. The electrochemical behavior of the modified electrode was investigated by cyclic and square wave voltammetry, and the effect of experimental variables, such as dispersion and loading of cobalt (II)-phthalocyanine, together with optimum conditions for sensing the analyte by square wave voltammetry were assessed. In addition, the absence of a significant memory effect combined with the ease of electrode preparation led to the development of a sensitive and direct method to determine tartaric acid in wines. Interferences from other low molecular weight organic acids commonly present in wines were circumvented by using a multiway calibration technique, successfully obtaining the second order advantage by modeling voltammetric data with unfolded partial least square with residual bilinearization (U-PLS/RBL). A linear response range between 10 and 100 μmol L−1 (r = 0.9991), a relative prediction error of 4.55% and a recovery range from 96.41 to 102.43% were obtained. The proposed method is non-laborious, since it does not use sample pretreatment such as filtration, extraction, pre-concentration or cleanup procedures.

Kinetics and Mechanism of Oxidation of Tartaric Acid by N-Chloronicotinamide (NCN)

The oxidation of tartaric acid by N-chloronicotinamide in the presence of H2SO4 is studied. First order kinetics with respect to NCN is observed. The kinetics results indicate fractional order dependence about [tartaric acid]. Inverse first order in [nicotinamide] and inverse fractional order about [H+] are noted. Rate of the reaction increases with a decrease in the percentage of acetic acid. The values of rate constants observed at four different temperatures were utilized to calculate the activation parameters. A suitable mechanism consistent with the experimental findings has been proposed.

Electrocatalytic Behavior of Mediators during Anodic Oxidation of Tartaric Acid at Platinum Electrodes

The effect of the nature and concentration of different halide salts (NaBr, NaCl and NaF) was followed by electrochemical measurements in an alkaline media. Based on the interesting results that were obtained, the electrochemical oxidation (EO) of tartaric acid (TA) with Pt electrodes was performed in the absence and presence of those substances, in order to verify their influence in indirect electrocatalytic mechanisms. A slow EO was observed in the absence of mediators. Conversely, with halide salts, the rate of the electrochemical incineration was significantly enhanced in the following order Cl− < Br− < F−. The rate of the mediated process was practically independent of applied current density (30 and 60 mA cm−2). Energy efficiency and energy consumption parameters were estimated, as well as the by-products were detected by GC/MS technique.

Anionic-micelles assisted oxidation of tartaric acid by permanganate: A kinetic and mechanistic approach

Abstract In this study, we demonstrate the catalytic effects of sodium dodecylbenzenesulphonate (SDBS) on the oxidation of tartaric acid by permanganate. UV–visible spectroscopic data revealed that the reaction proceeds through the formation of a transient species between the reactants. The values of ∆ e = 12.8 × 105 mol− 1 dm3 cm− 1 and Kc = 6.5 × 10− 4 mol− 1 dm3 were calculated from the kinetic data. Reaction-time profiles show that the reaction has an induction period (slow step) followed by an auto-acceleration path (fast step). SDBS is found to be stable in presence of MnO4−. The reaction follows first-order kinetics with respect to tartaric acid under pseudo-first-order conditions in absence and presence of SDBS. The observed results are discussed in terms of pseudo-phase model of the micelles proposed by Menger and Portony. The values of activation energy = 99 kJ mol− 1 and 59 kJ mol− 1 were calculated by using Arrhenius equation, respectively, in absence and presence of SDBS micelles. The probable mechanisms have also been proposed and discussed. Presence of silver ions also catalyzed of reaction rates.

Kinetics and Mechanism of Oxidation of Tartaric Acid by N-Chloronicotinamide (NCN)

The oxidation of tartaric acid by N-chloronicotinamide in the presence of HClO4 is studied. First order kinetics with respect to NCN is observed. The kinetics results indicate fractional order dependence about [tartaric acid]. Inverse first order in [nicotinamide] and inverse fractional order about [H+] are noted. Rate of the reaction increases with a decrease in the percentage of acetic acid. The values of rate constants observed at four different temperatures were utilized to calculate the activation parameters. A suitable mechanism consistent with the experimental findings has been proposed.

Kinetics and Mechanism of Oxidation of Tartaric Acid by N-Chloronicotinamide (NCN)

The oxidation of tartaric acid by N-chloronicotinamide in the presence of HClO4 is studied. First order kinetics with respect to NCN is observed. The kinetics results indicate fractional order dependence about [tartaric acid]. Inverse first order in [nicotinamide] and inverse fractional order about [H+] are noted. Rate of the reaction increases with a decrease in the percentage of acetic acid. The values of rate constants observed at four different temperatures were utilized to calculate the activation parameters. A suitable mechanism consistent with the experimental findings has been proposed.

Selection of Promoter and Micellar Catalyst for Chromic Acid Oxidation of Tartaric Acid in Aqueous Medium at Room Temperature

Abstract Chromic acid oxidation of tartaric acid in aqueous acid media produces glycolaldehyde very sluggishly at room temperature. Suitable combination of promoter (2,2′-bipyridine and 1,10-phenanthroline) and micellar catalyst (sodium dodecyl sulphate, cetylpyridinium chloride, triton X-100) enhances the rate of reaction to almost 14-fold. Observation showed that anionic surfactant (SDS) and nonionic surfactant (TX-100) accelerates the process but cationic surfactant (CPC) retards the reaction. The efficient combination for the production of glycolaldehyde from tartaric acid is found to be 1,10-phenanthroline and SDS.

Kinetics and Mechanism of Aquachlororuthenium (III) Catalyzed Oxidation of Tartaric Acid by Acid Bromate

The kinetics of the oxidation of Ru (III) catalyzed oxidation of tartaric acid by potassium bromate in aqueous perchloric acid medium at constant ionic strength was investigated in the temperature range 303- 318 K. The reactions exhibit first order kinetics at low concentration of bromate, tending to zero order at high concentration. Zero order kinetics with respect to (tartaric acid) and first order kinetics in (Ru (III)) were observed in the oxidation of tartaric acid. A positive effect on the rate of reaction has been found on the successive addition of (H + ) and (Cl - ). Variation in mercuric acetate concentration, (Hg(OAc)2) and ionic strength of the medium did not bring any significant change on the rate of reaction. The first order rate constant increases with decrease in the dielectric constant of the medium. The values of rate constants observed at four different temperatures were utilized to calculate the activation parameters. Formic acid and carbon dioxide have been identified as main oxidation products of the reaction. A plausible mechanism from the results of kinetic studies, reaction stoichiometry and product analysis has been proposed.

Anodic Oxidation of Tartaric Acid at Different Electrode Materials

Aim of the present communication is to show experimental results, and related conclusions, on the electrochemical oxidation (EO) of tartaric acid (TA), which has been oxidized at Ti/PbO2, Ti/Pt, Pt and HBDD electrodes at different current densities in acidic media. TA complete mineralization has been achieved only at HBDD and Ti/PbO2, being higher the faradaic efficiency at the latter electrode. At Pt electrode, the electroxidation was found to be extremely slow, in acidic conditions. The experimental evidence has shown that the main factor is the interaction of the organic substrate and hydroxyl radicals with the electrode surface, during TA oxidation. In the case of the EO of oxalic acid (OA) in acidic media that was previously studied, better results were obtained at the Pt electrode, supporting the idea that the interaction of organic substrate with the electrode surface, was the main determining parameter and based on the results here reported, this idea was confirmed for TA, more complex compound than OA. Keywords: Adsorption, Aqueous media, Electrochemical incineration, Electrode, Tartaric acid, oxidation, fermentation, electroactive, electrochemistry, trooxidation

Kinetic studies on the metal(II) tartarate–peroxomonosulfate reaction

AbstractThe kinetics of oxidation of tartaric acid (TAR) by peroxomonosulfate (PMS) in the presence of Cu(II) and Ni(II) ions was studied in the pH range 4.05–5.20 and also in alkaline medium (pH ∼12.7). The rate was calculated by measuring the [PMS] at various time intervals. The metal ions concentration range used in the kinetic studies was 2.50 × 10−5 to 1.00 × 10−4 M [Cu(II)], 2.50 × 10−4 to 2.00 × 10−3M [Ni(II)], 0.05 to 0.10 M [TAR], and µ = 0.15 M. The metal(II) tartarates, not TAR/tartarate, are oxidized by PMS. The oxidation of copper(II) tartarate at the acidic pH shows an appreciable induction period, usually 30–60 min, as in classical autocatalysis reaction. The induction period in nickel(II) tartarate is small. Analysis of the [PMS]–time profile shows that the reactions proceed through autocatalysis. In alkaline medium, the Cu(II) tartarate–PMS reaction involves autocatalysis whereas Ni(II) tartarate obeys simple first‐order kinetics with respect to [PMS]. The calculated rate constants for the initial oxidation (k1) and catalyzed oxidation (k2) at [TAR] = 0.05 M, pH 4.05, and 31°C are Cu(II) (1.00 × 10−4 M): k1 = 4.12 × 10−6 s−1, k2 = 7.76 × 10−1 M−1s−1 and Ni(II) (1.00 × 10−3 M): k1 = 5.80 × 10−5 s−1, k2 = 8.11 × 10−2 M−1 s−1. The results suggest that the initial reaction is the oxidative decarboxylation of the tartarate to an aldehyde. The aldehyde intermediate may react with the alpha hydroxyl group of the tartarate to give a hemi acetal, which may be responsible for the autocatalysis. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 620–630, 2011

Room-Temperature Weak Ferromagnetism Induced by Point Defects in α-Fe2O3

Unusual room-temperature weak ferromagnetism alpha-Fe(2)O(3) was prepared by heating the mixture of commercial alpha-Fe(2)O(3) (as raw material) and tartaric acid at a mild temperature of 250 degrees C. This reaction involves a fast heating and cooling process resulting from the self-catalyzed oxidation of tartaric acid. Careful chemical analyses confirmed that no any ferromagnetic impurities, such as Fe, Fe(3)O(4), amorphous iron oxide and gamma-Fe(2)O(3,) were present in the treated sample. The unusual weak ferromagnetism was then attributed to the formation of a large amount of point defects in the treated sample during the peculiar synthetic process. Such a mechanism is supported by the result of annealing, which reduces the amount of point defects and thereby reestablishes the original antiferromagnetism in alpha-Fe(2)O(3).

Room-temperature ferromagnetic/ferroelectric BiFeO3 synthesized by a self-catalyzed fast reaction process

Bismuth ferrite BiFeO3 has attracted a great deal of interest because of its multiferroic properties. However, BiFeO3 synthesized by conventional methods in the forms of single crystals, ceramics or thin films only exhibit ferroelectricity and antiferromagnetic order at room temperature, with weak ferromagnetism appearing at very low temperatures. To fully explore the potential of multiferroism in such applications as new memory devices, it is necessary to synthesize materials that show ferromagnetic order at room temperature as well, which will a priori allow for magnetoelectric coupling. In this paper, we report a new synthetic technique for the synthesis of BiFeO3 that exhibits unusual ferromagnetic properties. This method involves a low temperature fast solid state reaction based on tartaric acid. The mechanism of the reaction deduced from thermogravimetric analysis (TGA) and differential thermal analysis (TGA) suggests that a self-catalyzed process in the presence of iron and bismuth oxides triggers the oxidation of tartaric acid at low temperature and gives out a large amount of heat, which, in turn, leads to the formation of BiFeO3. The BiFeO3 synthesized in this way is ferromagnetic. The origin of the unusual ferromagnetism is supposed to be associated with point defects of oxygen vacancies generated during the self-catalyzed extremely fast exothermic reaction, which suppress the spin circular cycloid in BiFeO3. Ferroelectric hysteresis loops are displayed in the BiFeO3 samples. The presence of room temperature ferromagnetic and ferroelectric orders makes BiFeO3 a truly multiferroic material potentially interesting in such applications as magnetoelectric devices.

A Kinetic and Mechanistic Study on the Oxidation of Hydroxy Acids by N‐Bromophthalimide in the Presence of a Micellar System

AbstractThe kinetics of oxidation of some α‐hydroxy acids viz. Tartaric acid (TA) and Malic acid (MA) by N‐bromophthalimide (NBP) were studied in the presence of a cationic surfactant, cetyltrimethylammonium bromide (CTAB), in perchloric acid medium at 313 K. The oxidation of TA and MA by N‐bromophthalimide in the presence of CTAB is faster than in the absence of surfactant. The rate of oxidation of hydroxy acids was found to be in the order: TA &gt; MA. First order kinetics with respect to NBP was observed in the oxidation of both hydroxy acids. The kinetics results indicate that the first order kinetics in hydroxy acids at lower concentrations tends towards a zero order at its higher concentrations. Inverse fractional order in [H+] and [phthalimide] were noted throughout its tenfold variation. With a progressive increase in [CTAB], the rate of reaction increased, reaches a maximum value and then constancy in kΨ was observed. Variation of [Hg(OAc)2] and ionic strength (μ) of the medium did not bring about any significant change in the rate of reaction. The applicability of different kinetic models viz. the Piszkiewicz cooperative model, the Raghvan and Srinivasan model, and the Menger–Portnoy model were tested to explain the observed micellar effects. The effect of [CTAB] on the activation parameters was explored to rationalize the micellar effect. The values of rate constants observed at four different temperatures were utilized to calculate the activation parameters. A suitable mechanism consistent with the experimental findings has been proposed. The index of cooperativity and the micelle binding constant have been calculated.

The production of yellow pigments from (+)-catechin and dihydroxyfumaric acid in a model wine system

The oxidation of tartaric acid by hydroxyl radicals, produced by gamma-irradiation of aqueous solutions of tartaric acid, was shown to generate dihydroxyfumaric acid. To confirm the importance of this oxidative degradation pathway in wine oxidation, dihydroxyfumaric acid was itself reacted with (+)-catechin in a wine-like solution and the yellow pigments formed were identified by liquid chromatography mass spectrometry (LC-MS) studies as xanthylium cations. The concentration of these pigments increased if the wine-like system also contained 0.6 mg/L copper(II). The results clearly demonstrate a link between the production of yellow xanthylium cation pigments from (+)-catechin and the degradation of tartaric acid by hydroxyl radicals.

Hepatic Iron Overload Induces Hepatocellular Carcinoma in Transgenic Mice Expressing the Hepatitis C Virus Polyprotein

Despite the evidence of hepatic iron overload in patients with chronic hepatitis C, it remains unknown if iron overload is related to hepatocarcinogenesis in this condition. The aim of this study was to determine whether iron overload contributes to development of hepatocellular carcinoma (HCC) in transgenic mice expressing the hepatitis C virus (HCV) polyprotein. Male C57BL/6 transgenic mice expressing the HCV polyprotein and nontransgenic littermates were fed an excess-iron diet or control diet. Mice in each group were assessed for altered liver morphology and function and the development of liver tumors. Hepatic iron concentrations in mice fed the excess-iron diet were comparable to those of patients with chronic hepatitis C. There was no inflammation in transgenic and nontransgenic livers. Compared with mice in 3 other groups, transgenic mice fed the excess-iron diet showed marked hepatic steatosis including the centrilobular microvesicular type, ultrastructural alterations of the mitochondria and decreased degradation activity of fatty acid at 6 months, and greater hepatic content of lipid peroxidation products and 8-hydroxy-2'-deoxyguanosine at 12 months after initiation of feeding. The number of proliferating hepatocytes was significantly increased in mice fed the excess-iron diet but was not different between transgenic and nontransgenic mice. Hepatic tumors including HCC developed in 5 of 11 (45%) transgenic mice fed the excess-iron diet but not in mice in other groups at 12 months after initiation of feeding. Iron overload induces mitochondrial injury and increases the risk of HCC development in transgenic mice expressing the HCV polyprotein.

Enantiospecific Electrodeposition of Chiral CuO Films from Copper(II) Complexes of Tartaric and Amino Acids on Single-Crystal Au(001)

Chiral films of CuO were electrochemically deposited onto achiral Au(001) using chiral precursors such as tartaric acid and the amino acids alanine and valine to complex the Cu(II). The chirality of the electrodeposited films was dictated by the chiral solution precursor. X-ray diffraction pole figures and azimuthal scans, in conjunction with stereographic projections, were used to determine the absolute configuration and enantiomeric excess of the chiral CuO films. CuO films grown from l-tartaric acid have a (11̄1̄) orientation with an enantiomeric excess of 95%, while the films grown from d-tartaric acid have a (1̄11) orientation with an enantiomeric excess of 93%. CuO films grown from chiral amino acids have two types of chiral orientations, each showing lower enantiomeric excess compared with the films deposited from tartaric acid. The films grown from l-alanine and l-valine solution have an excess of the (1̄11) and (1̄1̄1̄) orientations, while the films grown from d-alanine and d-valine have an excess of (11̄1̄) and (111). Films of CuO deposited from a solution of achiral glycine consist of a racemic mixture of the (1̄11) and (11̄1̄) orientations. Chiral CuO films deposited on both single-crystal Au(001) and polycrystalline Au films were shown to exhibit chiral recognition for the electrochemical oxidation of tartaric acid.

Oxidation of Two ?-Hydroxy Acids by Vanadium(V)

The pathways for the oxidation of tartaric acid and citric acid by vanadium(V) in perchloric acid medium have been studied at 303 K by following the formation of vanadium(IV) spectrophotometrically at 760 nm. The oxidation reaction displays fractional order dependence with respect to both the α-hydroxy acids concentrations as well as fractional (tartaric acid) and first order (citric acid) dependencies with respect to the perchloric acid concentration. It does not matter at all whether the ionic strength was varied or was maintained constant. The reaction rate remains essentially constant with increasing ionic strength in the tartaric acid oxidation, but decreases slightly in the citric acid case. A decrease of the dielectric constant of the reaction medium results in a rate decrease in the tartaric acid oxidation and in a rate enhancement in the citric acid reaction. The activation parameters were obtained from studies of the reactions at different temperatures (293 to 313 K). Based on the experimentally determined rate laws oxidation mechanisms and theoretical rate laws were proposed.

Influence of light exposure, ethanol and copper(II) on the formation of a precursor for xanthylium cations from tartaric acid

The production of xanthylium cation pigments was greatly increased when an aged, tartaric acid buffered, 12% (v/v) aqueous ethanol solution was used in a model white wine system. This suggested the formation of a precursor to the pigments during the ageing of the tartaric acid solution. On examining factors responsible for the generation of tartaric acid oxidation products in wine-like solutions it was observed that on exposure of samples to sunlight, glyoxylic acid, a known precursor to xanthylium cations, was produced. The production of glyoxylic acid was achieved in both the absence and presence of ethanol and copper(II). Hydrogen peroxide was also detected in these solutions. The results were consistent with the presence of glyoxylic acid in the aged tartaric acid buffered, 12% (v/v) aqueous ethanol solution that had frequent aeration and periodic exposure to sunlight throughout its storage. Studies on the role of hydrogen peroxide in the production of glyoxylic acid were also investigated. On the addition of hydrogen peroxide to tartaric acid solutions, with heating at 45°C in darkness, glyoxylic acid was only determined in solutions without ethanol.