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1
Content available Insect antifeedant potent quinoxalines
Lakshmanan K., Sekar K. G., Sathiyendiran V., Muthuvel I.
International Letters of Chemistry, Physics and Astronomy
|
2015
|
Vol. 41
82--87
EN
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 Achoea Janata L.
2
Content available (E)-N-substitutedbenzylidene-4-methoxyanilines as Insect Antifeedants
Lakshmanan K., Sekar K. G., Sathiyendiran V., Suresh R.
International Letters of Chemistry, Physics and Astronomy
|
2015
|
Vol. 41
118--123
EN
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 leafdiscs bio assay method using 4th instar larvae Achoea Janata L.
3
Content available Spectral QSAR and QPR study of some (E)-4-(((2 hydroxy-6-(substituted phenyl)-1,6 dihydropyrimidin 4-yl)methyl)diazenyl)benzoic acid derivatives
Thirunarayanan G., Sekar K. G.
International Letters of Chemistry, Physics and Astronomy
|
2014
|
Vol. 17, iss. 1
10--20
EN
A series of titled compounds were synthesized and recorded the infrared and NMR spectra. The assigned spectral group frequencies were correlated with Hammett substituent constants, F and R parameter. From the statistical analysis results, the effect of substituents on the spectral group frequencies has been studied.
4
Content available Spectral correlations in some substituted styryl (E)-4-((2-oxopropyl) diazenyl) benzoic acids
Sathiyendiran V., Sekar K. G., Thirunarayanan G., Arulkumaran R., Sundararajan R., Kamalakkannan D., Suresh R., Manikanadan V., Vijayakumar R., Vanangamudi G.
International Letters of Chemistry, Physics and Astronomy
|
2014
|
Vol. 11, iss. 1
33-43
EN
A series of titled compounds were prepared and analyzed their purities by literature method. The infrared and NMR spectral group frequencies of the compounds were assigned and correlated with Hammett substituent constants, F and R constants using single and multi linear regression analysis. From the results of statistical analysis, the effect of substituents on the above spectral frequencies was discussed.
5
Content available Microwave assisted sulphated titania catalyzed aldol condensation: Synthesis of some (E) 3-(2-naphthyl)-1-(substituted phenyl)-2-propen-1-ones under solvent-free conditions
Janaki P., Sekar K. G., Thirunarayanan G.
International Letters of Chemistry, Physics and Astronomy
|
2014
|
Vol. 9
16--22
EN
A series of titled chalcones were synthesized by aldol condensation between 2-naphthaldehyde and various substituted acetophenones using solid acidic solid sulphated titania catalyst under microwave irradiation. The yields of these chalcones are more than 90 %. The synthesized chalcones are characterized by their physical constants, analytical and spectroscopic data.
6
Content available Insect antifeedant potent unsaturated 1,3-oxazine-2-amines
Thirunarayanan G., Renuka V., Sekar K.G., Lakshmanan K., Anbarasu K.
International Letters of Chemistry, Physics and Astronomy
|
2014
|
Vol. 4
66--81
EN
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.
7
Content available Infrared and NMR spectral Hammett correlations in 4-(2-naphthyl)-5,6-dihydro-6-(substituted phenyl)-4H-1,3-oxazine-2-amines
Thirunarayanan G., Pazhamalai S., Sekar K. G.
International Letters of Chemistry, Physics and Astronomy
|
2014
|
Vol. 8
38--46
EN
A series containing ten titled compounds have been synthesised and recorded the IR and NMR spectra. From the spectra the infrared νNH, C=N, C-O-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.
8
Content available Hammett spectral correlations in some aryl 1,3-oxazine-4-thione derivatives
Thirunarayanan G., Sekar K. G.
International Letters of Chemistry, Physics and Astronomy
|
2014
|
Vol. 17, iss. 2
193--200
EN
A series of some aryl 1,3-oxazine-4-thione derivatives have been synthesized by 1-methyl imidazole catalyzed three component one pot synthetic method in room temperature. The purities of these thiones were studied by their physical constants and spectroscopic data. The infrared and 13C NMR spectral data of CN and CS were correlated with Hammett substituent constants, F and R parameters using single and multi-linear regression analysis. From the results of statistical analysis, the effect of substituent on the spectral data was studied.
9
Content available Hammett spectral correlations in benzofuranyl flavonols
Thirunarayanan G., Sekar K. G.
International Letters of Chemistry, Physics and Astronomy
|
2014
|
Vol. 6
39--47
EN
A series containing eleven benzofuranyl flavonols have been prepared by cyclization of 3-hydroxybenzofuranyl chalcones with 30 % hydrogen peroxide in the presence of sodium bicarbonate. The synthesized flavonols were characterized by their physical constants, analytical and spectroscopic data. The infrared spectral νOH, CO stretches(cm-1), NMR chemical shifts of OH, CO(δ, ppm) of these flavonols were assigned and correlated with Hammett substituent constants, F and R parameters using single and multi linear regression analysis. From the results of statistical analyses, the effects of substituents on the above group frequencies were discussed.
10
Content available Synthesis and spectral studies of some N-[(E)-phenylmethylidene]benzenesulfonamides
Sekar K. G., Thirunarayanan G.
International Letters of Chemistry, Physics and Astronomy
|
2013
|
Vol. 8, iss. 3
249-258
EN
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.
11
Content available Solvent-free synthesis and spectral linearity of some (E)-2-(substituted benzylideneamino)-N-(3-chloro-4-fluorophenyl)-hexahydro-2H cyclopenta[b]thiophene-3-carboxamides
Thirunarayanan G., Sekar K. G.
International Letters of Chemistry, Physics and Astronomy
|
2013
|
Vol. 8, iss. 2
160-174
EN
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 ? (cm-1) of CO, NH, C-N, C-Cl, C-F, C=N, and the NMR chemical shifts (?, 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.
12
Content available Preheated fly-ash catalyzed cyclization ofchalcones: Synthesis of some substituted pyrazole-1-carbothioamides and spectral correlations in 3-(3,4-dichlorophenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1 carbothioamides
Thirunarayanan G., Sekar K. G.
International Letters of Chemistry, Physics and Astronomy
|
2013
|
Vol. 10, iss. 1
18-34
EN
Some substituted 1-thiocarbomyl pyrazolines including 3-(3,4-dichlorophenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamides using solvent-free preheated fly-ash catalyzed cyclization between chalcones and thiosemicarbazide microwave irradiation. The yields of these thiocarbomyl pyrazolines are more than 80 %. The purities of these synthesised pyrazoline derivatives are checked by their physical constants and spectral data earlier reported in the literature The spectral data of these 3-(3,4-dichlorophenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamides had been correlated, using single and multi-linear regression analysis.
13
Content available Oxidation of α, Β -unsaturated alcohols by quinaldinium fluorochromate
Sekar K. G., Periyasamy S. K.
International Letters of Chemistry, Physics and Astronomy
|
2012
|
Vol. 5
8-19
EN
The kinetics of oxidation of α, Β-unsaturated alcohols (allyl alcohol, Crotyl alcohol, Cinnamyl alcohol) by quinaldinium fluorochromate has been studied in aqueous acid medium at 313 K. α, Β- unsaturated alcohols were converted to the corresponding acrolein, crotonaldehyde and cinnamaldehyde. The reaction is first order each in oxidant, substrate and H+. The decrease in di electric 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 conducted at four different temperatures and activation parameters were calculated. From the observed kinetic results a suitable mechanism consistent with rate law has been proposed. The relative reactivity order was found to be Cinnamyl alcohol > Crotyl alcohol > Allyl alcohol.
14
Kinetics of oxidation of oxine by pyridinium dichromate
Palaniappan AN., Bharathi K., Sekar K.G.
Polish Journal of Chemistry
|
1998
|
Vol. 72, nr 1
122-126
EN
The kinetics of oxidation of 8-hydroxyquinoline (oxine) by pyridinium dichromate has been studied in 60% acetic acid-water (v/v) medium. The reaction order is one with respect to oxidant, second with respect to the substrate and zero with respect to hydrogen ion concentration. Decrease of the dielectric constant of the medium, reduces the rate of the reaction. Increase in ionic strength has no effect on the reaction rate. The reaction does not induce the polymerization of acrylonitrile. From the kinetic data obtained, the activation parameters have been calculated and a plausible mechanism has been proposed.
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