K G SEKAR - Academia.edu (original) (raw)
Papers by K G SEKAR
A convergent approach for the synthesis of new pyrazolyl bipyridinyl substituted coumarin derivat... more A convergent approach for the synthesis of new pyrazolyl bipyridinyl substituted coumarin derivatives as antimicrobials
The conversion of S-phenylmercaptoacetic acid to the corresponding sulfoxide was performed in 50%... more The conversion of S-phenylmercaptoacetic acid to the corresponding sulfoxide was performed in 50% (v/v) wateraceticacid mixture in the presence of perchloric acid medium. The order with respect to S-phenylmercaptoacetic acid and quinoxalinium dichromate were both one and inverse first order with respect to hydrogen ion concentration. Decrease in dielectric constant of the medium increased the rate of reaction. Ionic strength had a considerable influence on a reaction rate, indicating the involvement of a dipole in the rate-limiting step. A suitable mechanism and rate law in consonance with the observed facts is proposed
The study was carried out to determine the concentration of heavy metal ions in and around this a... more The study was carried out to determine the concentration of heavy metal ions in and around this area. Thirty two ground water samples were collected from in and around Udaiyarpalyam taluk during pre-monsoon and post monsoon season during the year of 2014. The concentration of trace metals such as iron, lead, cadmium, and chromium were determined using atomic absorption spectrophotometer and the results were compared with the World Health Organization (WHO) and Bureau Indian standard (BIS) values. It reveals revealed the presence of some heavy metals in few ground water samples and hence refers heavy metal contamination of water sources. The result shows that most of the groundwater is deteriorated less than the permissible limit of WHO.
The kinetics of oxidation of allyl alcohol by imidazolium dichromate has been studied in 40% acet... more The kinetics of oxidation of allyl alcohol by imidazolium dichromate has been studied in 40% acetic acid- water (v/v) medium in the presence of perchloric acid at 313 K. The reaction is first order with respect to [oxidant] and [substrate] . The reaction is acid catalysed one. The decrease in dielectric constant of the medium increases the rate of the reaction. Increase in Ionic strength by the addition of sodium perchlorate has no effect on the rate constant. There is no polymerization with acrylonitrile. The reaction has been studied at four different temperatures and the activation parameters were calculated. Acrolein has been identified as the product of oxidation. From the observed kinetic results a suitable mechanism consistent with rate data has been proposed
Oxidation Communications, 2003
The kinetics of oxidation of salicylaldehyde by imidazolium dichromate has been studied in 60% ac... more The kinetics of oxidation of salicylaldehyde by imidazolium dichromate has been studied in 60% acetic acid-water (v/v) medium. The reaction shows unit order dependence with respect to oxidant, substrate and hydrogen ion concentration. Increase in ionic strength has no perceptible change in the reaction rate. The rate of the reaction increases with increase in percentage of acetic acid. The reaction does not induce the polymerisation of ethylacrylate. From the kinetic data obtained, the activation parameters have been calculated and a suitable mechanism has been proposed.
Journal of Pharmacognosy and Phytochemistry, 2014
Phytochemical screening of Citrullus colocynthis belonging to the family Cucurbitaceae was carrie... more Phytochemical screening of Citrullus colocynthis belonging to the family Cucurbitaceae was carried out for finding its medicinal values. A qualitative analysis was performed for the identification of the presence of different composition of elements. The leaf, root, flower (male, female), fruit (pulp, hull, seed) were photochemical analyzed separately and which shows the presence of alkaloids, carbohydrates, and flavonoids. Tannins, gums and mucilages are found to be absent.
A series containing ten titled compounds have been synthesised and recorded the IR and NMR spectr... more A series containing ten titled compounds have been synthesised and recorded the IR and NMR spectra. From the spectra the infrared νNH, C=N, CO -C stretches, NMR chemical shifts of (δ, ppm) NH and C=N were assigned and correlated with Hammett substituent constants, F and R parameters using single regression analysis. From the results, the effects of substituent on the above spectral frequencies were discussed.
Spectral correlations in some substituted styryl (E)-4-((2-oxopropyl) diazenyl) benzoic acids
Polish Journal of Chemistry, 1998
The kinetics of oxidation of distyryl ketone by qu inaldinium fluorochromate has been studied in ... more The kinetics of oxidation of distyryl ketone by qu inaldinium fluorochromate has been studied in aqueo us acetic acid medium. The order of the reaction is found to b e one with respect to oxidant and hydrogen io n. The order with respect to substrate is found to be fraction al. The rate increases with increase in the perce ntage of acetic acid. Variation of ionic strength has no effect on the reaction rate. The reaction does not induce the polymerization of acrylonitrile. The products of oxidation have be en found to cinnamic acid and phenyl acetaldehyde. Th reaction rate has been determined at different temperatures and the activation parameters also calculated. A su itable mechanism consistent with the observed kinetics has been proposed.
The kinetics of oxidation of thiomalic acid by quinaldinium fluorochromate(QnFC) has been studied... more The kinetics of oxidation of thiomalic acid by quinaldinium fluorochromate(QnFC) has been studied in non - aqueous medium. The oxidation kinetics was followed photoelectric colorimetrically in the temperature range of 30°C–60°C. The reaction shows unit order dependence each with respect to substrate and oxidant. The reaction is catalyzed by hydrogen ions. The hydrogen ion dependence takes in the form kobs = a + b [H+]. The reaction rate decreases with increasing the concentration of Mn2+ ions. The reaction does not induce the polymerization of acrylonitrile. A plausible mechanism has been proposed in the formation of a thio ester and its decomposition which occurs in the slow step.
Organic Chemistry: An Indian Journal, 2014
In the present study we have synthesized some 1-thiocarbomyl pyrazolines including 3-phenyl-5-(su... more In the present study we have synthesized some 1-thiocarbomyl pyrazolines including 3-phenyl-5-(substitutedphenyl)-4,5-dihydro-1H-pyrazole-1- carbothioamides using solvent free SiO2:H3PO4 catalyzed cyclization of chalcones with thiosemicarbazide under microwave irradiation. The yields of the 1H-pyrazole-1-carbothioamides are more than 85%. The synthesised pyrazole-1-carbothioamideswere characterized by their analytical, physical and spectral data. The infrared iC=N, C=S, NH (cm-1) frequencies, NMR chemical shifts (a, ppm) Ha, Hb, Hc, C=N, C=S of synthesised 3-phenyl-5- (substitutedphenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamides were correlated with Hammett substituent constants, F and R parameters. From the results of statistical analyses the effects of substituent on the above functional group of pyrazole-1-carbothiamides.
![Research paper thumbnail of Solvent-Free Synthesis and Spectral Linearity of Some (E)-2-(substituted benzylideneamino)-N-(3-chloro-4-fluorophenyl)-hexahydro-2H-cyclopenta[b]thiophene-3-carboxamides](https://attachments.academia-assets.com/102962190/thumbnails/1.jpg)
](International Letters of Chemistry, Physics and Astronomy, 2013
Some (E)-2-(substituted benzylideneamino)-N-(3-chloro-4-fluorophenyl)-hexahydro-2H-cyclopenta[b]t... more Some (E)-2-(substituted benzylideneamino)-N-(3-chloro-4-fluorophenyl)-hexahydro-2H-cyclopenta[b]thiophene-3-carboxamide derivatives have been synthesized by SiO2:H3PO4 catalyzed solvent-free condensation of 2-amino-N-(3-chloro-4-fluorophenyl)-hexahydro-2H-cyclopenta [b]thiophene-3-carboxamide and various substituted benzaldehydes in microwave irradiation. The yield of the imine-carboximido derivatives has been found to be more than 85 %. The purity of all imine-carboximido derivatives has been checked using their physical constants and spectral data. The spectral data of the imine-carboximido derivatives such as infrared ν (cm-1) of CO, NH, C-N, C-Cl, C-F, C=N, and the NMR chemical shifts (δ, ppm) of NH, CH, CO and C=N have been correlated with Hammett substituent constants, F and R parameters. From the results of statistical analysis, the effects of substituent on the above spectral group absorptions have been discussed.
![Research paper thumbnail of Synthesis and Spectral Studies of some N-[(E)-Phenylmethylidene]benzenesulfonamides](https://attachments.academia-assets.com/102962188/thumbnails/1.jpg)
](International Letters of Chemistry, Physics and Astronomy, 2013
A series of some N-[(E)-phenylmethylidene]benzenesulfonamide derivatives have been synthesised us... more A series of some N-[(E)-phenylmethylidene]benzenesulfonamide derivatives have been synthesised using solid SiO2-H3PO4 catalyst under solvent free conditions in microwave irradiation. The synthesised E-N-benzene sulfonilimines purities have been verified by their physical constants and spectroscopic data. The spectral frequencies are correlated with Hammett substituent constants, F and R parameters using linear regression analysis. From the results of statistical analysis the effect of substituents on the group frequencies will be discussed.
International Letters of Chemistry, Physics and Astronomy, 2013
Insect antifeedant activities of some halo substituted aryl 1,3-oxazine-2-amines have been measur... more Insect antifeedant activities of some halo substituted aryl 1,3-oxazine-2-amines have been measured using 4th instar larvae Achoea janata L by castor leaf discs-Dethler’s method. The highly halo substituted oxazine amines have shown good insect antifeedant activities. The 1,3-oxazine amines have been synthesised by greener method by solvent-free cyclization of aryl enones with urea under microwave irradiation. The yields of the oxazines were more than 80%. The synthesised oxazines were characterized by their physical constants, analytical and spectroscopic data.
International Journal of Scientific Research in Knowledge, 2013
Totally ten 3-(9-anthryl)-4,5-dihydro-5-(3-substitutedphenyl)-1 H-pyrazolines have been prepared ... more Totally ten 3-(9-anthryl)-4,5-dihydro-5-(3-substitutedphenyl)-1 H-pyrazolines have been prepared by solvent-free cyclization of 2(E)-1-(substituted phenyl)-3-(9-anthryl)-2-propen-1-ones and hydrazine hydrate in presence of fly-ash:H 2 SO 4 catalyst. These pyrazolines were characterized by their physical constants and spectroscopic data. The assigned infrared νC=N, NH(cm-1), NMR chemical shifts(ppm) of δNH, H 4 , H 4′ , H 5 and C=N data are correlated with Hammett substituent constants, F and R parameters using regression analysis. From the results of statistical analysis, the effects of substituent on the above group frequencies have been discussed.
International Letters of Chemistry, Physics and Astronomy, 2014
Some substituted aryl Schiff’s bases [(E)-N-substitutedbenzylidene-4-methoxyanilines] have been p... more Some substituted aryl Schiff’s bases [(E)-N-substitutedbenzylidene-4-methoxyanilines] have been prepared and their purities were checked by their physical constants and spectroscopic data reported earlier. The insect antifeedant activities of these Schiff’s bases have been studied by leaf-discs bio assay method using 4th instar larvae AchoeaJanata L.
International Letters of Chemistry, Physics and Astronomy, 2014
Some 6-substituted aryl quinoxalines have been prepared and their purities were checked by their ... more Some 6-substituted aryl quinoxalines have been prepared and their purities were checked by their physical constants and spectroscopic data reported earlier. The insect antifeedant activities of these quinolones were studied by leaf-discs bio assay method using 4th instar larvae AchoeaJanata L.
A convergent approach for the synthesis of new pyrazolyl bipyridinyl substituted coumarin derivat... more A convergent approach for the synthesis of new pyrazolyl bipyridinyl substituted coumarin derivatives as antimicrobials
The conversion of S-phenylmercaptoacetic acid to the corresponding sulfoxide was performed in 50%... more The conversion of S-phenylmercaptoacetic acid to the corresponding sulfoxide was performed in 50% (v/v) wateraceticacid mixture in the presence of perchloric acid medium. The order with respect to S-phenylmercaptoacetic acid and quinoxalinium dichromate were both one and inverse first order with respect to hydrogen ion concentration. Decrease in dielectric constant of the medium increased the rate of reaction. Ionic strength had a considerable influence on a reaction rate, indicating the involvement of a dipole in the rate-limiting step. A suitable mechanism and rate law in consonance with the observed facts is proposed
The study was carried out to determine the concentration of heavy metal ions in and around this a... more The study was carried out to determine the concentration of heavy metal ions in and around this area. Thirty two ground water samples were collected from in and around Udaiyarpalyam taluk during pre-monsoon and post monsoon season during the year of 2014. The concentration of trace metals such as iron, lead, cadmium, and chromium were determined using atomic absorption spectrophotometer and the results were compared with the World Health Organization (WHO) and Bureau Indian standard (BIS) values. It reveals revealed the presence of some heavy metals in few ground water samples and hence refers heavy metal contamination of water sources. The result shows that most of the groundwater is deteriorated less than the permissible limit of WHO.
The kinetics of oxidation of allyl alcohol by imidazolium dichromate has been studied in 40% acet... more The kinetics of oxidation of allyl alcohol by imidazolium dichromate has been studied in 40% acetic acid- water (v/v) medium in the presence of perchloric acid at 313 K. The reaction is first order with respect to [oxidant] and [substrate] . The reaction is acid catalysed one. The decrease in dielectric constant of the medium increases the rate of the reaction. Increase in Ionic strength by the addition of sodium perchlorate has no effect on the rate constant. There is no polymerization with acrylonitrile. The reaction has been studied at four different temperatures and the activation parameters were calculated. Acrolein has been identified as the product of oxidation. From the observed kinetic results a suitable mechanism consistent with rate data has been proposed
Oxidation Communications, 2003
The kinetics of oxidation of salicylaldehyde by imidazolium dichromate has been studied in 60% ac... more The kinetics of oxidation of salicylaldehyde by imidazolium dichromate has been studied in 60% acetic acid-water (v/v) medium. The reaction shows unit order dependence with respect to oxidant, substrate and hydrogen ion concentration. Increase in ionic strength has no perceptible change in the reaction rate. The rate of the reaction increases with increase in percentage of acetic acid. The reaction does not induce the polymerisation of ethylacrylate. From the kinetic data obtained, the activation parameters have been calculated and a suitable mechanism has been proposed.
Journal of Pharmacognosy and Phytochemistry, 2014
Phytochemical screening of Citrullus colocynthis belonging to the family Cucurbitaceae was carrie... more Phytochemical screening of Citrullus colocynthis belonging to the family Cucurbitaceae was carried out for finding its medicinal values. A qualitative analysis was performed for the identification of the presence of different composition of elements. The leaf, root, flower (male, female), fruit (pulp, hull, seed) were photochemical analyzed separately and which shows the presence of alkaloids, carbohydrates, and flavonoids. Tannins, gums and mucilages are found to be absent.
A series containing ten titled compounds have been synthesised and recorded the IR and NMR spectr... more A series containing ten titled compounds have been synthesised and recorded the IR and NMR spectra. From the spectra the infrared νNH, C=N, CO -C stretches, NMR chemical shifts of (δ, ppm) NH and C=N were assigned and correlated with Hammett substituent constants, F and R parameters using single regression analysis. From the results, the effects of substituent on the above spectral frequencies were discussed.
Spectral correlations in some substituted styryl (E)-4-((2-oxopropyl) diazenyl) benzoic acids
Polish Journal of Chemistry, 1998
The kinetics of oxidation of distyryl ketone by qu inaldinium fluorochromate has been studied in ... more The kinetics of oxidation of distyryl ketone by qu inaldinium fluorochromate has been studied in aqueo us acetic acid medium. The order of the reaction is found to b e one with respect to oxidant and hydrogen io n. The order with respect to substrate is found to be fraction al. The rate increases with increase in the perce ntage of acetic acid. Variation of ionic strength has no effect on the reaction rate. The reaction does not induce the polymerization of acrylonitrile. The products of oxidation have be en found to cinnamic acid and phenyl acetaldehyde. Th reaction rate has been determined at different temperatures and the activation parameters also calculated. A su itable mechanism consistent with the observed kinetics has been proposed.
The kinetics of oxidation of thiomalic acid by quinaldinium fluorochromate(QnFC) has been studied... more The kinetics of oxidation of thiomalic acid by quinaldinium fluorochromate(QnFC) has been studied in non - aqueous medium. The oxidation kinetics was followed photoelectric colorimetrically in the temperature range of 30°C–60°C. The reaction shows unit order dependence each with respect to substrate and oxidant. The reaction is catalyzed by hydrogen ions. The hydrogen ion dependence takes in the form kobs = a + b [H+]. The reaction rate decreases with increasing the concentration of Mn2+ ions. The reaction does not induce the polymerization of acrylonitrile. A plausible mechanism has been proposed in the formation of a thio ester and its decomposition which occurs in the slow step.
Organic Chemistry: An Indian Journal, 2014
In the present study we have synthesized some 1-thiocarbomyl pyrazolines including 3-phenyl-5-(su... more In the present study we have synthesized some 1-thiocarbomyl pyrazolines including 3-phenyl-5-(substitutedphenyl)-4,5-dihydro-1H-pyrazole-1- carbothioamides using solvent free SiO2:H3PO4 catalyzed cyclization of chalcones with thiosemicarbazide under microwave irradiation. The yields of the 1H-pyrazole-1-carbothioamides are more than 85%. The synthesised pyrazole-1-carbothioamideswere characterized by their analytical, physical and spectral data. The infrared iC=N, C=S, NH (cm-1) frequencies, NMR chemical shifts (a, ppm) Ha, Hb, Hc, C=N, C=S of synthesised 3-phenyl-5- (substitutedphenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamides were correlated with Hammett substituent constants, F and R parameters. From the results of statistical analyses the effects of substituent on the above functional group of pyrazole-1-carbothiamides.
International Letters of Chemistry, Physics and Astronomy, 2013
Some (E)-2-(substituted benzylideneamino)-N-(3-chloro-4-fluorophenyl)-hexahydro-2H-cyclopenta[b]t... more Some (E)-2-(substituted benzylideneamino)-N-(3-chloro-4-fluorophenyl)-hexahydro-2H-cyclopenta[b]thiophene-3-carboxamide derivatives have been synthesized by SiO2:H3PO4 catalyzed solvent-free condensation of 2-amino-N-(3-chloro-4-fluorophenyl)-hexahydro-2H-cyclopenta [b]thiophene-3-carboxamide and various substituted benzaldehydes in microwave irradiation. The yield of the imine-carboximido derivatives has been found to be more than 85 %. The purity of all imine-carboximido derivatives has been checked using their physical constants and spectral data. The spectral data of the imine-carboximido derivatives such as infrared ν (cm-1) of CO, NH, C-N, C-Cl, C-F, C=N, and the NMR chemical shifts (δ, ppm) of NH, CH, CO and C=N have been correlated with Hammett substituent constants, F and R parameters. From the results of statistical analysis, the effects of substituent on the above spectral group absorptions have been discussed.
International Letters of Chemistry, Physics and Astronomy, 2013
A series of some N-[(E)-phenylmethylidene]benzenesulfonamide derivatives have been synthesised us... more A series of some N-[(E)-phenylmethylidene]benzenesulfonamide derivatives have been synthesised using solid SiO2-H3PO4 catalyst under solvent free conditions in microwave irradiation. The synthesised E-N-benzene sulfonilimines purities have been verified by their physical constants and spectroscopic data. The spectral frequencies are correlated with Hammett substituent constants, F and R parameters using linear regression analysis. From the results of statistical analysis the effect of substituents on the group frequencies will be discussed.
International Letters of Chemistry, Physics and Astronomy, 2013
Insect antifeedant activities of some halo substituted aryl 1,3-oxazine-2-amines have been measur... more Insect antifeedant activities of some halo substituted aryl 1,3-oxazine-2-amines have been measured using 4th instar larvae Achoea janata L by castor leaf discs-Dethler’s method. The highly halo substituted oxazine amines have shown good insect antifeedant activities. The 1,3-oxazine amines have been synthesised by greener method by solvent-free cyclization of aryl enones with urea under microwave irradiation. The yields of the oxazines were more than 80%. The synthesised oxazines were characterized by their physical constants, analytical and spectroscopic data.
International Journal of Scientific Research in Knowledge, 2013
Totally ten 3-(9-anthryl)-4,5-dihydro-5-(3-substitutedphenyl)-1 H-pyrazolines have been prepared ... more Totally ten 3-(9-anthryl)-4,5-dihydro-5-(3-substitutedphenyl)-1 H-pyrazolines have been prepared by solvent-free cyclization of 2(E)-1-(substituted phenyl)-3-(9-anthryl)-2-propen-1-ones and hydrazine hydrate in presence of fly-ash:H 2 SO 4 catalyst. These pyrazolines were characterized by their physical constants and spectroscopic data. The assigned infrared νC=N, NH(cm-1), NMR chemical shifts(ppm) of δNH, H 4 , H 4′ , H 5 and C=N data are correlated with Hammett substituent constants, F and R parameters using regression analysis. From the results of statistical analysis, the effects of substituent on the above group frequencies have been discussed.
International Letters of Chemistry, Physics and Astronomy, 2014
Some substituted aryl Schiff’s bases [(E)-N-substitutedbenzylidene-4-methoxyanilines] have been p... more Some substituted aryl Schiff’s bases [(E)-N-substitutedbenzylidene-4-methoxyanilines] have been prepared and their purities were checked by their physical constants and spectroscopic data reported earlier. The insect antifeedant activities of these Schiff’s bases have been studied by leaf-discs bio assay method using 4th instar larvae AchoeaJanata L.
International Letters of Chemistry, Physics and Astronomy, 2014
Some 6-substituted aryl quinoxalines have been prepared and their purities were checked by their ... more Some 6-substituted aryl quinoxalines have been prepared and their purities were checked by their physical constants and spectroscopic data reported earlier. The insect antifeedant activities of these quinolones were studied by leaf-discs bio assay method using 4th instar larvae AchoeaJanata L.