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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.

Sugirtha Devi S.,Kamaraj College
Journal of Molecular Catalysis A: Chemical | Year: 2014

Oxidative decarboxylation of phenylsulfinylacetic acid (PSAA) and several substituted PSAAs with three oxo(salen)chromium(V) complexes in the presence of nitrogen bases are investigated in 100% acetonitrile medium using spectrophotometric technique. The nitrogenous bases such as imidazole, 1-methyl imidazole and pyridine catalyse the reaction and Michaelis-Menten kinetics is observed with respect to these bases. Among the various bases employed, imidazole with strong π donating ability shows the least accelerating effect and the maximum catalytic activity is observed with pyridine. Both the electron donating and electron withdrawing substituents in PSAA accelerate the reaction rate. The Hammett plots for the three oxo(salen)chromium(V) complexes with three nitrogen bases display a nonlinear upward curvature. The Hammett parameter ρ, changes from large negative to small positive values as the substituents are changed from electron donating to electron withdrawing groups. A mechanism involving direct oxygen transfer from oxo(salen)chromium(V)-nitrogen base adduct to PSAA with simultaneous decarboxylation to yield sulfone is proposed. The nonlinear Hammett plot has been ascribed to a shift in the rate determining step caused by the formation and decomposition of the sulfonium ion intermediate which is susceptible to substituent effect. © 2014 Elsevier B.V.

The mechanism of oxidative decarboxylation of phenylsulfinylacetic acids (PSAA) by oxo(salen)Cr(V)+ ion in the presence of ligand oxides has been studied spectrophotometrically in acetonitrile medium. Addition of ligand oxides (LO) causes a red shift in the λmax values of oxo(salen) complexes and an increase in absorbance with the concentration of LO along with a clear isobestic point. The reaction shows first-order dependence on oxo(salen)-chromium(V)+ ion and fractional-order dependence on PSAA and ligand oxide. Michaelis-Menten kinetics without kinetic saturation was observed for the reaction. The order of reactivity among the ligand oxides is picoline N-oxide > pyridine N-oxide > triphenylphosphine oxide. The low catalytic activity of TPPO was rationalized. Both electron-withdrawing and electron-donating substituents in the phenyl ring of PSAA facilitate the reaction rate. The Hammett plots are non-linear upward type with negative ρ value for electron-donating substituents, (ρ- = -0.740 to -4.10) and positive ρ value for electron-withdrawing substituents (ρ+ = +0.057 to +0.886). Non-linear Hammett plot is explained by two possible mechanistic scenarios, electrophilic and nucleophilic attack of oxo(salen)chromium(V)+-LO adduct on PSAA as the substituent in PSAA is changed from electron-donating to electron-withdrawing. The linearity in the log k vs. Eox plot confirms single-electron transfer (SET) mechanism for PSAAs with electron-donating substituents. © 2016 Elsevier Ltd.

Flora X.H.,Alagappa University | Flora X.H.,Kamaraj College | Ulaganathan M.,Nanyang Technological University | Rajendran S.,Alagappa University
International Journal of Polymeric Materials and Polymeric Biomaterials | Year: 2013

In this work, polymer electrolytes composed of PAN/PMMA/LiClO4 with different plasticizers are prepared using solvent casting technique. Ionic conductivity of the electrolytes is evaluated with the help of ac impedance study at various temperatures. Structural and the complexation of the prepared electrolytes are studied by XRD and FTIR analysis, respectively. Thermogravimetric/differential thermal analysis (TG/DTA) is used to find the thermal stability of the polymer electrolytes. PAN/PMMA/EC/LiClO 4-based plasticized polymer electrolyte is found to possess optimal properties in terms of conductivity and thermal stability. Porous nature of the polymer gel electrolytes is also confirmed by SEM analysis. © 2013 Copyright Taylor and Francis Group, LLC.

Kanagaprabha S.,Kamaraj College | Asvinimeenaatci A.T.,Nmssvn College | Rajeswarapalanichamy R.,Nmssvn College | Iyakutti K.,Madurai Kamaraj University
Physica B: Condensed Matter | Year: 2012

First principles calculation were performed using Vienna ab-initio simulation package within the frame work of density functional theory (DFT) to understand the electronic properties of magnesium hydride. At normal pressure, the most stable structure of MgH2 is rutile type with a wide band gap of 3.52 eV, which agrees well with the available data. A pressure induced semi-conductor to metallic transition at a pressure of 92.54 GPa is predicted. Our results indicate a sequence of pressure induced structural phase transition in MgH2. The obtained sequence of phase transition was α→γ→β→δ→ε at a pressure of 0.37 GPa, 3.89 GPa,7.23 GPa and 11.26 GPa, respectively. Thus our results indicate that MgH2 is one of the best hydrogen storage material and the maximum storage capacity achieved was 7.7%. © 2011 Elsevier B.V. All rights reserved.

Flora X.H.,Alagappa University | Flora X.H.,Kamaraj College | Ulaganathan M.,Nanyang Technological University | Babu R.S.,Vellore Institute of Technology | Rajendran S.,Alagappa University
Ionics | Year: 2012

Abstracts: Polymer blend electrolytes composed of poly(acrylonitrile) (PAN) and poly(methyl methacrylate) (PMMA) as host polymers and lithium perchlorate as a salt were prepared by solution casting technique. The electrolytes were prepared for different ratios of host polymers with standard weight ratio of the ionic salt (LiClO 4). Among the different concentrations, the polymer electrolyte film containing PAN/PMMA (75:25 wt.%) was found to be a suitable candidate for the battery applications on the basis of ionic conductivity and thermal stability. Complexation, structural reorganizations and ionic conductivity as a function of temperature were studied using X-ray diffraction analysis, Fourier transform infrared, and ac impedance analysis, respectively. Thermal stability of the electrolyte film having maximum ionic conductivity was also studied using thermogravimetric analysis. © 2012 Springer-Verlag.

Yogesh Kumar J.S.,National Coral Reef Research Institute Haddo | Sreeraj C.R.,National Coral Reef Research Institute Haddo | Sornaraj R.,Kamaraj College
Indian Journal of Fisheries | Year: 2011

The Gulf of Mannar, located in the south-east coast of India with an area of 10,500 km 2 (8° 47' - 9° 15' N and 78° 12' - 79° 14' E), is a major fishing zone in the Indian waters. Several fisher communities make their livelihood by exploiting finfishes and shellfishes as well as marine algae and other resources from this area. Extensive survey for sea slugs was conducted during 2008 in the sub-tidal regions of Vembar and Tuticorin groups of islands in the Gulf of Mannar Biosphere Reserve using SCUBA. The present study brings out 14 species of nudibranchs new to this region. Also one species each under cephalaspidean and sacoglossan opisthobranchs described in the paper are new to this region. A total of 20 species of opisthobranchs were recorded during the study. Literature reveals that 47 species of nudibranchs have been recorded previously from the Gulf of Mannar region.

Subbu Lakshmi S.,Kamaraj college
Asian Journal of Pharmaceutical and Clinical Research | Year: 2013

Objective: To examine the utilization of seafood processing wastes for artificial cultivation of medicinal mushroom and composting in laboratory condition. Method: The selected agro-industrial wastes (e.g., coir pith, woodchips, sugarcane bagasse) were mixed with fishery waste in specific ratio (1:1).The substrates which are not mixed with fishery waste are regarded as control. All the above materials (1:1,control) were allowed to decompose about 15 days. The composted materials were placed in heat resistant transparent polyethylene bags. Each sterile bag was then aseptically inoculated with G.lucidum. The bags were then incubated under ambient temperature and controlled humidity. Results: The maximum biological yield per bed was obtained with sugarcane bagasse control bed 64.78 g/bed.The lowest yield was observed in woodchips (1:1) 4.6 g/bed. Based on mass obtained of G.lucidum the best substrates were ordered of like woodchips>coir>sugarcane. Conclusion: The scope of this work is sea food wastes could be used to cultivate a medicinal mushroom while at the same time promoting environmental sustainability.

Flora X.H.,Alagappa University | Flora X.H.,Kamaraj College | Ulaganathan M.,Nanyang Technological University | Rajendran S.,Alagappa University
International Journal of Electrochemical Science | Year: 2012

Polymer blend electrolytes are prepared for various concentration of LiClO4 salt with the constant ratio of PAN and PMMA polymers using solution casting technique. The structural and complex formations of the basic constituents and their complexes are analyzed by XRD and FTIR spectroscopic techniques. The effect of salt concentration on the ionic conductivity and the temperature dependence of ionic conductivity in the range 302-373K have been studied using ac impedance spectroscopy analysis. The maximum ionic conductivity value is found to be of the order of 0.562 x 10-5 Scm-1 for the film containing PAN (75 wt.%) PMMA (25wt.%) with LiClO4 (wt.8%). The thermal behaviours of the films are ascertained from thermo gravimetric analysis and differential scanning calorimetry. The sample exhibits higher ionic conductivity has also been subjected to scanning electron microscopy inorder to study the micro structure of the electrolyte system. © 2012 by ESG.

Asvini Meenaatci A.T.,Nmssvn College | Prabha S.K.,Kamaraj College | Palanichamy R.R.,Nmssvn College | Iyakutti K.,Madurai Kamaraj University
AIP Conference Proceedings | Year: 2012

The high pressure structural investigations of HfN and ZrN have been studies using ab initio calculations. It is predicted that ZrN undergoes a structural phase transition from NaCl to ZB structure at around 90.17GPa whereas there is no phase transition for HfN. However at higher pressure (at 108.67GPa) HfN undergo a phase transition from ZB to WC structure. Apart from this, the ground state properties, elastic constants and superconducting transition temperature are calculated and compared with the available results. © 2012 American Institute of Physics.

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