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Riva J.S.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Riva J.S.,CONICET | Bierbrauer K.,CONICET | Beltramo D.M.,CONICET | And 2 more authors.
Electrochimica Acta | Year: 2012

The complexation of two hydroxyethylcellulose, of different molecular weights, SC230 and SC240, with the anionic surfactants perfluorodecanoic acid, PFDA, and perfluorooctanoic acid, PFOA, has been studied. For this purpose, the anions transfer current across a water/1,2-dichloroethane interface was employed to quantify PFDA and PFOA concentration in the absence or in the presence of the polyelectrolyte. When polymers were added in increasing amounts to solutions containing PFDA or PFOA, a gradual decrease in current values was observed, evincing the binding of the anions to the polymer. Peak Current values for the transfer, were used for the drawing up the binding isotherms, which were fitted by Satake and Yang theory. Cooperative binding was observed, but all fluorinated acids gave a similar cooperativity parameter, and it was found that both the overall constant as well as the cooperative binding process, increases with the molecular weight of the polymer. © 2012 Elsevier Ltd.


Bossolasco A.G.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Vila J.A.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Burgos Paci M.A.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Malanca F.E.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Arguello G.A.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc
Chemical Physics | Year: 2014

CF3CF2CF2CF2OONO2 was synthesized from the photolysis of CF3CF2CF 2CF2I, in presence of NO2 and O2. Alkyl peroxynitrates (CxF2x +1OONO2) could be formed in the atmospheric degradation of chlorofluorocarbons, hydrofluorocarbons and hydrofluoroethers. We present here the synthesis and characterization (IR and UV absorption cross sections) of CF3CF2CF2CF2OONO2 and its comparison with those corresponding to other perfluoro alkyl peroxynitrates. The thermal stability was studied as a function of total pressure (from 9.0 to 417 mbar) and temperature (from 283 to 293 K) using infrared spectroscopy. Kinetic parameters measured for the thermal dissociation were Ea = (81 ± 4) kJ/mol and A = 4.8 × 1012. DFT calculations at the B3LYP/6-311+G* level were used to explore the ground state potential energy surface. Geometrical parameters, conformer populations and vibrational spectra are presented. The calculated activation energy was 81.3 kJ mol-1 in excellent agreement with experimental results. Atmospheric implications are discussed. © 2014 Elsevier B.V. All rights reserved.


Ovejero J.M.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Fernandez R.A.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Dassie S.A.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc
Journal of Electroanalytical Chemistry | Year: 2012

In this paper, we present the general equations for a model that describes ion transfer reactions across the oil|water interface assisted by a ligand, under forced hydrodynamic conditions. Our analysis is mainly focused on the effect of mechanical stirring of the aqueous or organic phase during the potential sweep, and its influence on the limiting diffusion currents. The model was solved numerically using explicit finite difference; the results of digital simulations are obtained for simple and facilitated ion transfer. The corresponding transfer mechanism was analyzed in terms of the current-potential profiles, concentration profiles and interfacial distributions, obtained from digital simulations. © 2011 Elsevier B.V. All rights reserved.


Blanco M.B.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Rivela C.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Rivela C.,National University of Asunción | Teruel M.A.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc
Chemical Physics Letters | Year: 2013

Rate coefficients of the reactions of OH radicals and Cl atoms with 2,2,2 trifluoroethyl butyrate have been determined at 298 K and atmospheric pressure. The decay of the organics was followed using a gas chromatograph with a flame ionization detector (GC-FID) and the rate coefficients were determined using the relative rate method. This is the first kinetic study for these reactions under atmospheric pressure. The kinetic data are used to update the correlation kOH vs. kCl for different fluoroesters, to develop reactivity trends in terms of halogen substitution and to estimate the tropospheric lifetime of 2,2,2 trifluoroethyl butyrate. © 2013 Elsevier B.V. All rights reserved.


Fernandez R.A.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Velasco M.I.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Rossi L.I.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Dassie S.A.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc
Journal of Electroanalytical Chemistry | Year: 2010

Cyclic voltammetry applied to liquid/liquid interfaces and nuclear magnetic resonance spectroscopy were used to analyze the stability of tylosin A in aqueous solutions in acid conditions. Cyclic voltammetry was employed to characterize the charge transfer processes for tylosin A and tylosin B across the H2O/1,2-dichloroethane interface. Electrochemical study includes the transfer potential dependence of pH value, the elucidation of the mechanism of transfer using mechanical control of convective flux, and the determination of partition coefficient values and diffusion coefficient values employing the change of voltammetric current with external parameters. Degradation process of tylosin A was monitored and tylosin B or desmycosin was isolated and then identified and characterized by nuclear magnetic resonance spectroscopy and electrochemical techniques. © 2010 Published by Elsevier B.V.


Dassie S.A.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc
Journal of Electroanalytical Chemistry | Year: 2010

In this paper we present the general equations for a model of anion transfer reactions across the oil{divides}water interface assisted by a neutral ligand. Our analysis mainly focuses on the effect of water autoprotolysis. The equations reported here allow us to simulate the system under a variety of possible conditions. The formation of complex with j:k anion-to-ligand stoichiometry is analyzed. Three different models are compared: buffered solutions (BASA model) and unbuffered solutions with and without considering water autoprotolysis (UBASA and UBAS model respectively). Moreover, the analytical relationships for the BASA model between half-wave potential and the initial concentration of anion and ligand are developed. © 2010 Elsevier B.V. All rights reserved.


Garcia J.I.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Oviedo M.B.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Dassie S.A.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc
Journal of Electroanalytical Chemistry | Year: 2010

In this paper, we present the general equations for a model that describes ion transfer reactions across the oil|water interface assisted by a neutral protonatable ligand in the presence of a buffer solution. Our analysis mainly focuses on the effect of the concentration of the buffered solution and its identity on the voltammetric signal, the pH profile and the buffer capacity of the system. The model was solved using explicit finite difference with exponentially expanding space grid. The results of digital simulations were corroborated by experimental results obtained for the quinine transfer across the H 2O|1,2-dichloroethane interface in the presence of phosphate buffer, and the corresponding transfer mechanism was analyzed in terms of the current-potential and concentration profiles obtained from the digital simulations. © 2010 Elsevier B.V. All rights reserved.


Blanco M.B.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Bejan I.,University of Wuppertal | Bejan I.,Al. I. Cuza University | Barnes I.,University of Wuppertal | And 2 more authors.
Environmental Science and Technology | Year: 2010

A 1080 L environmental chamber with in situ FTIR spectroscopy detection was used to study the product distribution and the mechanism of the Cl-initiated photooxidation of a series of fluoroacetates. The gas-phase reactions of Cl atoms with ethyl trifluoroacetate (CF3C(O)OCH2CH 3), methyl trifluoroacetate (CF3C(O)OCH3), and methyl difluoroacetate (CF2HC(O)OCH3) were investigated at 296 ± 2 K and atmospheric pressure (∼760 Torr) of synthetic air. The fate of the fluoroalkoxy radicals formed in the reaction with Cl atoms mainly occurs through (i) an H-atom abstraction by reaction with O2, to produce the corresponding fluoroanhydride and (ii) an α-ester rearrangement via a five-membered ring intermediate to give the corresponding fluoroacetic acid. The yields of fluoroacids (CF2XC(O)OH, with X = H, F) obtained were as follows: 78 ± 5,23 ± 2, and 30 ± 5% for CF3C(O)OCH2CH3, CF3C(O)OCH 3, and CF2HC(O)OCH3, respectively. Yields of <20, < 80, and <55% have been estimated forthe anhydride formation from CF3C(O)OCH2CH3, CF3C(O)OCH 3, and CF2HC(O)OCH3, respectively. Formation of CF2O, with yield of 13 ± 2% has been observed for the reaction of Cl with CF2HC(O)OCH3. The measured yields are rationalized in terms of mechanisms consisting of competitive reaction channels for the radicals formed in the oxidation, that is, reaction with O2, α-ester rearrangement and a decomposition pathway. The stability of the five-membered transition state of the α-ester rearrangement is correlated with the acid yields observed for the different fluoroacetates. Atmospheric implications, especially with regard to the fluorocarboxylic acid formation, are discussed. © 2010 American Chemical Society.


Blanco M.B.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Bejan I.,University of Wuppertal | Bejan I.,Al. I. Cuza University | Barnes I.,University of Wuppertal | And 2 more authors.
Environmental Science and Technology | Year: 2010

A product study is reported on the gas-phase reactions of OH radicals and Cl atoms with methyl acrylate. The experiments were performed in a 1080-L quartz-glass chamber in synthetic air at 298 ± 2 K and 760 ± 10 Torr using long-path in situ FTIR spectroscopy for the analysis of the reactants and products. In the absence of NOx the major product observed in the OH reaction is methyl glyoxylate, with formaldehyde as a coproduct. For the reaction with Cl only formyl chloride (HC(O)Cl), CO, and HCl could be positively identified as products, however, the concentration-time behavior of these products show that they are secondary products and originate from the further oxidation of a major primary product. From this behavior and a comparison with simulated spectra unidentified bands in the residual product spectra are tentatively attributed to a compound of structure CH2ClC(O)C(O) OCH3, i.e., formation of methyl 3-chloro-2-oxopropanoate from the reaction of Cl with methyl acrylate. The present results are compared with previous results where available and simple atmospheric degradation mechanisms are postulated to explain the formation of the observed products. © 2010 American Chemical Society.


Guastavino J.F.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Buden M.E.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Garcia C.S.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc | Rossi R.A.,Institute Investigaciones En Fisicoquimica Of Cordoba Infiqc
Arkivoc | Year: 2011

The synthesis of 3-benzazepin-2-ones using commercially available 2-(2-iodophenyl)acetic acid as starting material is described. The synthetic strategy involves the SRN1 substitution reaction in DMSO as solvent under photoinitiation, using ketone enolate ions as nucleophiles to obtain ε-oxo acids, followed by a condensation reaction of ε-oxo acids with ammonium acetate in glacial acetic acid to produce novel 3-benzazepin-2-ones. The target compounds are afforded in regular to good yields and the factors governing the distribution of substitution products are discussed. © ARKAT-USA, Inc.

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