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Selvi N.T.,Govindammal Aditanar College for Women
Journal of the Serbian Chemical Society | Year: 2015

The influence of cetyltrimethylammonium bromide, CTAB, on the oxidative decarboxylation of phenylsulfinylacetic acid, PSAA, and several meta- and para-substituted PSAAs by Cr(VI) was investigated in 95 % H2O-5 % CH3CN medium. The rate profile displayed a peculiar trend with an initial rate increase at low CTAB followed by sharp rate inhibition at higher CTAB concentrations. The initial rate acceleration could be explained by strong binding of SO4 2- on the positively charged micellar surface. The specific partitioning of PSAA in the micellar phase by hydrophobic interaction and the oxidizing species HCrO3 + in aqueous phase by electrostatic repulsion accounted for the rate retardation at higher CTAB concentrations. The Hammett plot with different substituted PSAAs showed excellent correlation affording negative ? value, which supports the proposed mechanism involving the intermediate formation of sulfonium cation. The obtained ? value in CTAB medium was found to be slightly lower than that in aqueous medium. Quantitative analysis of the rate data for the inhibition shown by CTAB was performed using the Menger-Portnoy and the Piszkiewicz pseudo-phase models. The binding constant for PSAA with micelles was evaluated from the Piszkiewicz cooperative model. Source

Praveena G.L.,Govindammal Aditanar College for Women
International Journal of ChemTech Research | Year: 2015

A new semiorganic nonlinear optical single crystal of Imidazole Potassium Chloride (IPC) has been grown successfully by slow evaporation method. Colourless, transparent IPC crystal of dimension 5 x 5 x 2 mm3 has been grown within a period of 21 days. The grown crystal was subjected to single crystal X-ray diffraction (XRD) analysis to determine the lattice parameters. The powder X-ray diffraction pattern of the grown crystal has been indexed. The presence of functional groups in the grown crystal was confirmed by fourier transform infrared spectroscopy (FTIR) analysis. The optical transmission property of the grown crystal was analysed using UV-Vis- NIR spectral analysis. The mechanical strength of the crystal was found out using Vickers microhardness test. The second harmonic generation (SHG) has been tested using Kurtz powder technique. © 2015, Sphinx Knowledge House. All rights reserved. Source

Selvi N.T.,Govindammal Aditanar College for Women | Devi S.S.,Kamaraj College
Journal of the Korean Chemical Society | Year: 2014

The oxidative decarboxylation of phenylsulfinylacetic acid (PSAA) by Cr(VI) in 20% acetonitrile - 80% water (v/v) medium follows overall second order kinetics, first order each with respect to [PSAA] and [Cr(VI)] at constant [H+] and ionic strength. The reaction is acid catalysed, the order with respect to [H+] is unity and the active oxidizing species is found to be HCrO3 +. The reaction mechanism involves the rate determining nucleophilic attack of sulfur atom of PSAA on chromium of HCrO3 + forming a sulfonium ion intermediate. The intermediate then undergoes a,β-cleavage leading to the liberation of CO2. The product of the reaction is found to be methyl phenyl sulfone. The operation of substituent effect shows that PSAA containing electron-releasing groups in the meta- and para-positions accelerate the reaction rate while electron withdrawing groups retard the rate. An excellent correlation is found to exist between log k2 and Hammett s constants with a negative value of reaction constant. The p value decreases with increase in temperature evidencing the high reactivity and low selectivity in the case of substituted PSAAs. Source

Praveena G.L.,Govindammal Aditanar College for Women
Optik | Year: 2016

The single crystals of d-alanine alaninium bromide (DAAB), a semiorganic nonlinear optical material has been grown successfully from aqueous solution by slow evaporation solution growth technique. Single-crystal X-ray diffraction analysis shows that the grown crystal belongs to the monoclinic system. The crystalline nature and its various planes of reflections were observed by powder XRD analysis. Thermal studies reveal that the crystal is stable up to 100 °C. The functional groups of the grown crystal were determined by FTIR spectral analysis. The existence of second harmonic generation signals was observed using Nd:YAG laser with fundamental wavelength of 1064 nm possessing SHG efficiency of 1.7 times of KDP. The optical transmittance window and the lower cutoff wavelength of the DAAB have been identified by UV-vis-NIR studies. The mechanical property of the grown crystal studied using Vickers microhardness measurement reveals that the crystal is a soft material. The encouraging results show that the DAAB crystals have great potential applications in optical devices. © 2016 Elsevier GmbH. All rights reserved. Source

Jansi Rani M.,Govindammal Aditanar College for Women | Murugan M.,Sri Kgs Arts College | Subramanian E.,Manonmaniam Sundaranar University
Indian Journal of Chemical Technology | Year: 2016

Prosopis spicigera L.wood (PSLW), a plant material used as fuel by the rural mass in India is carbonized and used as an adsorbent for the removal of Methylene Blue and Erythrosine B dyes from aqueous solution by batch and column methods. The adsorbent is characterized by BET method (Nitrogen adsorption at 77. K) for pore and textural properties, scanning electron microscopy for surface morphology, potentiometric titration for pHZPC, FTIR for surface functional group and Boehm estimation of surface functional groups. The adsorption of Methylene Blue and Erythrosine B dyes on PSLW carbon has been carried out at different pH, adsorbate concentrations and contact time, adsorbent dosage and temperature conditions to determine the optimum condition for adsorption. Batch adsorption experiments show that maximum adsorption of Methylene Blue and Erythrosine B dyes is found at pH 2.0 and 3.0 respectively. Pseudo second order kinetics (Lagergren), surface mass transfer and pore diffusion models were used to evaluate the kinetic parameters and adsorption mechanism. To describe the equilibrium isotherm process, the data are analyzed using Langmuir model. Thermodynamic parameters indicate the adsorption interaction is found to be spontaneous and exothermic in nature. Column data fits to the Thomas Model. © 2016, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved. Source

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