473-90-5Relevant academic research and scientific papers
Kinetics and mechanism of the oxidation of some carboxylates by a nickel(III) oxime-imine complex
Saha,Dutta,Gangopadhyay,Banerjee
, p. 225 - 230 (1997)
The kinetics of the oxidation of formate, oxalate, and malonate by [NiIII(L1)]2+ (where HL1 = 15-amino-3-methyl-4,7,10,13-tetraazapentadec-3-en-2-one oxime) were carried out over the regions pH 3.0-5.75, 2.80-5.50, and 2.50-7.58, respectively, at constant ionic strength and temperature 40°C. All the reactions are overall second-order with first-order on both the oxidant and reductant. A general rate law is given as - d/dt[NiIII(L1)2+] = kobs[NiIII(L1)2+] = (kd + nks[R])[NiIII(L1)2+], where kd is the auto-decomposition rate constant of the complex, ks is the electron transfer rate constant, n is the stoichiometric factor, and R is either formate, oxalate, or malonate. The reactivity of all the reacting species of the reductants in solution were evaluated choosing suitable pH regions. The reactivity orders are: kHCOOH > kHCOO(-); kH(2)ox > kHox(-) > kox(2-), and kH(2)mal > kHmal(-) mal(2-) for the oxidation of formate, oxalate, and malonate, respectively, and these trends were explained considering the effect of hydrogen bonded adduct formation and thermodynamic potential.
Importance of Unimolecular HO2 Elimination in the Heterogeneous OH Reaction of Highly Oxygenated Tartaric Acid Aerosol
Cheng, Chiu Tung,Chan, Man Nin,Wilson, Kevin R.
, p. 5887 - 5896 (2016/08/06)
Oxygenated organic molecules are abundant in atmospheric aerosols and are transformed by oxidation reactions near the aerosol surface by gas-phase oxidants such as hydroxyl (OH) radicals. To gain better insights into how the structure of an organic molecule, particularly in the presence of hydroxyl groups, controls the heterogeneous reaction mechanisms of oxygenated organic compounds, this study investigates the OH-radical initiated oxidation of aqueous tartaric acid (C4H6O6) droplets using an aerosol flow tube reactor. The molecular composition of the aerosols before and after reaction is characterized by a soft atmospheric pressure ionization source (Direct Analysis in Real Time) coupled with a high-resolution mass spectrometer. The aerosol mass spectra reveal that four major reaction products are formed: a single C4 functionalization product (C4H4O6) and three C3 fragmentation products (C3H4O4, C3H2O4, and C3H2O5). The C4 functionalization product does not appear to originate from peroxy radical self-reactions but instead forms via an α-hydroxylperoxy radical produced by a hydrogen atom abstraction by OH at the tertiary carbon site. The proximity of a hydroxyl group to peroxy group enhances the unimolecular HO2 elimination from the α-hydroxylperoxy intermediate. This alcohol-to-ketone conversion yields 2-hydroxy-3-oxosuccinic acid (C4H4O6), the major reaction product. While in general, C-C bond scission reactions are expected to dominate the chemistry of organic compounds with high average carbon oxidation states (OSC), our results show that molecular structure can play a larger role in the heterogeneous transformation of tartaric acid (OSC = 1.5). These results are also compared with two structurally related dicarboxylic acids (succinic acid and 2,3-dimethylsuccinic acid) to elucidate how the identity and location of functional groups (methyl and hydroxyl groups) alter heterogeneous reaction mechanisms.
Green oxidation of bio-lactic acid with H2O2 into tartronic acid under UV irradiation
Tian, Xuxia,Wang, Zhijian,Yang, Pengju,Hao, Ruipeng,Jia, Suping,Li, Na,Li, Li,Zhu, Zhenping
, p. 41007 - 41010 (2016/05/19)
Tartronic acid (TA) is a high value-added chemical widely used as a pharmaceutical product and a preservative; however, its synthesis technology is complicated and high cost. In this study, aqueous solutions of lactic acid were photochemically converted into TA via green oxidation by using hydrogen peroxide (H2O2).
Catalytic wet air oxidation of m-cresol over a surface-modified sewage sludge-derived carbonaceous catalyst
Yu, Yang,Wei, Huangzhao,Yu, Li,Gu, Bin,Li, Xianru,Rong, Xin,Zhao, Ying,Chen, Lili,Sun, Chenglin
, p. 1085 - 1093 (2016/02/27)
Sewage sludge-derived carbonaceous materials (SW) treated with different kinds of acids were used as catalysts for catalytic wet air oxidation (CWAO) of m-cresol. The SW catalysts were characterized by XRF, XRD, FTIR, XPS and TPD-MS. The results showed that SW treated with HNO3 (HNO3-SW) exhibited the best catalytic activity. When the initial concentration of m-cresol was 5000 mg L-1, the conversion of m-cresol reached 99.0% with HNO3-SW after 90 min at 160 °C and 0.66 MPa oxygen. Continuous experiments were carried out for 8 d to investigate the durability and catalytic performance of HNO3-SW in CWAO reaction. Some correlation was observed between the conversion of m-cresol and the content of carboxyl groups, indicating that the carboxyl group might play a key role in determining the catalytic activity of SW catalysts in CWAO reaction. Based on the intermediate products identified by GC-MS, HPLC-MS, IC and HRMS analyses, the oxidation pathways of m-cresol in CWAO were proposed.
Electrooxidation of glycerol on nickel and nickel alloy (Ni-Cu and Ni-Co) nanoparticles in alkaline media
Habibi, Biuck,Delnavaz, Nasrin
, p. 31797 - 31806 (2016/04/26)
In the present study, nickel (Ni) and Ni alloy (Ni-Cu and Ni-Co) nanoparticles modified carbon-ceramic electrodes (Ni/CCE, Ni-Cu/CCE and Ni-Co/CCE) were prepared by an electrochemical process for the oxidation of glycerol. In order to obtain the surface and physicochemical information, the Ni/CCE, Ni-Cu/CCE and Ni-Co/CCE were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and electrochemical techniques. Then, cyclic voltammetry and chronoamperometry were employed to characterize the electrocatalytic activity of the modified electrodes, Ni/CCE, Ni-Cu/CCE and Ni-Co/CCE, toward the oxidation of glycerol in 1.0 M NaOH solution. It was found that the Ni alloy nanoparticle modified electrodes are catalytically more active than the Ni/CCE, therefore, the alloying of the Ni with Cu and Co in the form of nanoparticles on the carbon-ceramic electrode, as a homemade substrate, greatly enhances the catalytic activity of the Ni-based electrocatalysts (as the non-platinum electrocatalysts) in glycerol oxidation.
Recombinant oxalate decarboxylase: Enhancement of a hybrid catalytic cascade for the complete electro-oxidation of glycerol
Abdellaoui, Sofiene,Hickey, David P.,Stephens, Andrew R.,Minteer, Shelley D.
, p. 14330 - 14333 (2015/09/21)
The complete electro-oxidation of glycerol to CO2 is performed through an oxidation cascade using a hybrid catalytic system combining a recombinant enzyme, oxalate decarboxylase from Bacillus subtilis, and an organic oxidation catalyst, 4-amino-TEMPO. This system is capable of electrochemically oxidizing glycerol at a carbon electrode collecting all 14 electrons per molecule.
Influence of silver on the glycerol electro-oxidation over AuAg/C catalysts in alkaline medium: A cyclic voltammetry and in situ FTIR spectroscopy study
Gomes,Garcia,Gasparotto,De Souza,Ferreira,Pires,Tremiliosi-Filho
, p. 361 - 368 (2014/12/10)
In the present work, we investigated the influence of silver on the glycerol electro-oxidation over carbon-supported AuAg catalysts by cyclic voltammetry and in situ FTIR spectroscopy. We observed that the presence of Ag in the bimetallic materials provided a more efficient catalyst in terms of the ability to electro-oxidize glycerol at relatively low potentials. On the other hand, the bimetallic catalysts were found to be less promising than the Au/C catalyst with respect to the reaction rate. Ag addition influenced the mechanism of glycerol electro-oxidation, favoring the C-C-C bond breaking, as evidenced by the selective formation of formic acid on the bimetallic catalysts. The impact of Ag on the glycerol electro-oxidation over AuAg/C may be driven by electronic modifications and Ag segregation on the catalysts surface.
Titania-based photocatalytic degradation of two nucleotide bases, cytosine and uracil
Elsellami,Sahel,Dappozze,Horikoshi,Houas,Guillard
, p. 207 - 213 (2014/11/27)
The photocatalytic degradation of two components of DNA and RNA, cytosine (C4H5N3O) and uracil (C4H 4N2O2) differing only by the presence of an amine or a carbonyl group was investigated in the presence of UV-irradiated TiO2 aqueous suspensions. The adsorption in the dark and under UV-A conditions, the photolysis, the kinetics of degradation, the fate of nitrogen and the identification of some intermediate products were investigated. The impact of pyrimidine cycles on the coverage of TiO2 under UV-A, the effect of NH2 substituent on the oxidation products and mineralization and the importance of carbonyl and amine groups on the fate of nitrogen atoms were evaluated. Electronic density was used to propose a possible chemical pathway. The comparison of the disappearance and mineralization rates in the photocatalytic process was discussed.
Catalytic oxidation of crude glycerol using catalysts based on Au supported on carbonaceous materials
Gil, Sonia,Marchena, Miriam,Fernández, Carmen María,Sánchez-Silva, Luz,Romero, Amaya,Valverde, José Luís
, p. 189 - 203 (2013/02/25)
Au catalysts supported on different carbon materials, such as graphite (G, 10 m2 g-1), ribbon-type carbon nanofibers (CNF-R, 109 m2 g-1), and carbon nanospheres (CNS, 3 m2 g-1), were prepared by the sol-gold method using tetrahydroxymethyl phosphonium chloride as the reducing agent. Different techniques were employed to characterize both the supports and the final Au catalysts: atomic absorption spectrometry, transmission electron microscopy, thermogravimetric analysis, X-ray diffraction, elemental analyses, N2 adsorption-desorption analysis, temperature-programmed reduction, and temperature-programmed decomposition. Au catalysts were tested in the liquid phase by selective oxidation of both commercial and crude glycerol, the latter obtained from the manufacture of biodiesel. Catalytic results obtained with commercial glycerol showed that the product distribution was dependent on the nature of the support and consequently on the Au particle size. The highest catalyst activity was achieved using highly crystalline carbon supports, supporting small-size (highly dispersed) Au particles. Accordingly the graphite-based catalyst exhibited higher catalytic activity than the CNF-R-based one. Catalytic results similar to those obtained with commercial glycerol were obtained when testing the stream resulting from a low cost neutralization procedure of the crude glycerol.
Identification of low molecular weight organic acids by ion chromatography/hybrid quadrupole time-of-flight mass spectrometry during Uniblu-A ozonation
Amorisco, Apollonia,Locaputo, Vito,Pastore, Carlo,Mascolo, Giuseppe
, p. 187 - 199 (2013/02/23)
RATIONALE: The balance of organic nitrogen and sulfur during ozonation of organic pollutants often shows a lack of complete mineralization. It follows that polar and ionic byproducts are likely to be present that are difficult to identify by liquid chromatography/mass spectrometry (LC/MS). METHODS: The structural elucidation of low molecular weight organic acids arising from Uniblu-OH ozonation has been investigated by ion chromatography/electrospray tandem mass spectrometry (IC/ESIMS/MS) employing a quadrupole timeofflight mass spectrometer. Unequivocal elemental composition of the byproducts was determined by a combination of mass accuracy and high spectral accuracy. RESULTS: The employed identification strategy was demonstrated to be a powerful method of unequivocally assigning a single chemical composition to each identified compound. The exact mass measurements of [M-H]- ions allowed the elemental formulae and related structures of eighteen byproducts to be determined confidently. The main degradation pathways were found to be decarboxylation and oxidation. The experimental procedure allowed the identification of both nitrogen- and sulfur-containing organic acid by-products arising from Uniblu-OH ozonation. CONCLUSIONS: The obtained results are of environmental relevance for the balance of organic nitrogen and sulfur during the ozonation of organic pollutants due to the lack of complete mineralization of the compounds containing these atoms. Copyright 2012 John Wiley & Sons, Ltd. Copyright
