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D'Souza O.J.,Bharathiar University | Mascarenhas R.J.,Bharathiar University | Mascarenhas R.J.,Electrochemistry Research Group | Satpati A.K.,Bhabha Atomic Research Center | And 2 more authors.
Ionics | Year: 2015

The electrocatalytic oxidation of l-tyrosine (Tyr) was investigated on a carboxylic acid functionalised multi-walled carbon nanotubes modified carbon paste electrode using cyclic voltammetry and amperometry. The surface morphology of the electrodes was studied using field emission (FE)-SEM images, and the interface properties of bare and modified electrodes were investigated by electrochemical impedance spectroscopy (EIS). The influence of the amount of modifier loading and the variation of the pH of the solution on the electrochemical parameters have been investigated. Cyclic voltammetry was carried out to study the electrochemical oxidation mechanism of Tyr, which showed an irreversible oxidation process at a potential of 637.0 mV at modified electrode. The anodic peak current linearly increased with the scan rate, suggesting that the oxidation of Tyr at modified electrode is an adsorption-controlled process. A good linear relationship between the oxidation peak current and the Tyr concentration in the range of 0.8–100.0 μM was obtained in a phosphate buffer solution at pH 7.0 with a detection limit of 14.0 ± 1.36 nM (S/N = 3). The practical utility of the sensor was demonstrated by determining Tyr in spiked cow’s milk and human blood serum. The modified electrode showed excellent reproducibility, long-term stability and antifouling effects. © 2015 Springer-Verlag Berlin Heidelberg


Chaskar A.,Postgraduate and Research Center | Chaskar A.,Polytechnic of Milan | Padalkar V.,Postgraduate and Research Center | Phatangare K.,Postgraduate and Research Center | And 2 more authors.
Synthetic Communications | Year: 2010

A simple, efficient, and ecofriendly procedure has been developed for the synthesis of quinoline and its derivatives in a one-pot reaction of aniline with crotonaldehyde or methyl vinyl ketone using phosphomolybdic acid as solid acid catalyst in miceller media. The catalyst was easily recycled and reused. Copyrigh © 2010 Taylor and Francis Group, LLC.


Pawar B.,Postgraduate and Research Center | Padalkar V.,Postgraduate and Research Center | Phatangare K.,Postgraduate and Research Center | Nirmalkar S.,Postgraduate and Research Center | Chaskar A.,National Taiwan University
Catalysis Science and Technology | Year: 2011

Triton X-100 aqueous micelle accelerates the rate of Baylis-Hillman reaction and enhances the product yield. The type and concentration of surfactants play prominent roles in the reaction. An aqueous micelle Triton X-100 is easily recovered and reused for four runs without substantial loss in yield. 1,4-diazabicyclo[2.2.2]octane (DABCO) (20 mol%) is found to be a good basic catalyst in aqueous micelle. Apparently, this protocol has several advantages such as green reaction medium, mild reaction condition, ease of product recovery and moderate-to-good yield of product. This journal is © The Royal Society of Chemistry 2011.


Limaye R.A.,Postgraduate and Research Center | Joseph A.R.,Postgraduate and Research Center | Natu A.D.,Postgraduate and Research Center | Paradkar M.V.,Postgraduate and Research Center
Journal of Chemical Research | Year: 2014

A convenient synthesis of (±)9-demethoxyeleutherin and (±)9-demethoxyisoeleutherin, the analogues of naturally occurring pyranonaphthoquinone antibiotics eleutherin and isoeleutherin, is described. The synthesis was achieved from 4-methoxy-1-napthol in four simple steps including Claisen rearrangement and oxymercuration-demercuration reactions. © 2014, Science Reviews 2000 Ltd. All rights reserved.


Limaye R.A.,Postgraduate and Research Center | Natu A.D.,Postgraduate and Research Center | Paradkar M.V.,Postgraduate and Research Center
Synthetic Communications | Year: 2014

GRAPHICAL ABSTRACT The article describes alternative method for the synthesis of (±) 9-demethoxyeleutherin and (±) 9-demethoxyisoeleutherin, the analogs of naturally occurring pyranonaphthoquinones antibiotics eleutherin and isoeleutherin. This methodology has provided the target molecules using a shorter route involving five simple chemical transformations with Nef reaction as a key step. All the intermediates and target molecules were completely characterized by spectral techniques and confirmed by comparison with literature data. Further we have extended Nef protocol toward formal synthesis of naturally occuring pyranonaphthoquinone pentalongin. We accomplished synthesis of of 2-(1,4-dimethoxynaphthalen-2-yl) acetic acid devoid of very toxic cyanide intermediates, which has been converted into pentalongin. © 2014 Copyright Taylor & Francis Group, LLC.


Al-Saeedi A.,Postgraduate and Research Center | Farooqui M.,Postgraduate and Research Center | Farooqui M.,Dr Rafiq Zakaria College for Women
Oriental Journal of Chemistry | Year: 2013

The (4+2) cycloaddition or the Dials-Alder reaction is one of the most important reactions in the field of organic synthesis. The Dials-Alder reaction well known to all chemists is 100 years old. The Diels-Alder reaction during that period it has been studied intensively, where there are more papers, many books and reviews in the Dials-Alder reactions making the complete study of these works impossible, therefore in this article we concentrate on the review and generalization of the Diels-Alder reaction of 9-substituted anthracene with a variety of dienophiles.


Limaye R.A.,Postgraduate and Research Center | Gaur P.,Postgraduate and Research Center | Paradkar M.V.,Postgraduate and Research Center | Natu A.D.,Postgraduate and Research Center
Synthetic Communications | Year: 2012

Synthesis of a key precursor 2-allyl-3-bromo-1,4-dimethoxynaphthalene (1) used in constructing various naturally occurring biologically active pyranonaphthoquinones is carried out utilizing easily available 1-methoxynaphthalene as a starting material. The synthesis was accomplished with Dakin's oxidation and Claisen rearrangement, thereby providing another easy approach toward (1) without involving highly lachrymatric 2-bromonaphthoquinone. Copyright © Taylor & Francis Group, LLC.


Walunj R.M.,Postgraduate and Research Center | Natu A.D.,Postgraduate and Research Center | Paradkar M.V.,Postgraduate and Research Center | Rojatkar S.R.,Bharati Vidyapeeth Deemed University
Synthetic Communications | Year: 2016

An efficient synthesis of Gramniphenol G identified as 2-(4′-Methoxyphenyl)-7,7-dimethyl-7H-furo[3,2-g]chromene and originally isolated from the plant Arundina gramnifolia belonging to orchidaceae family was accomplished starting from resorcinol. The key step involves the oxidative cyclization of o-vinyl phenol to provide benzofuran moiety. 2016 Copyright © Taylor & Francis Group, LLC

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