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A series containing twelve substituted styryl 2-phenothiazenyl ketones have been synthesized. The electrochemical potentials of carbonyl and vinyl groups were measured. These potentials are correlated with Hammett substituent constants, F and R parameters. From the results of statistical analyses, the effects of substituent on the group reduction potentials have been discussed. The insect antifeedant activities of these chalcones have been studied using 4 th instar larvae Achoea Janata L with castor leaf discs.

BackgroundGreen catalyst fly ash: H2SO4 was prepared by mixing fly ash and sulphuric acid. Microwave irradiations are applied for solid phase cyclization of 5-bromo-2-thienyl chalcones and phenyl hydrazine hydrate in the presence of fly ash: H2SO4 yields, 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines. These pyrazolines were characterized by their physical constants and spectral data. The antimicrobial activities of all synthesized pyrazolines have been studied.ResultsScanning electron microscopy (SEM) analysis shows the morphology changes between fly ash and the catalyst fly ash: H2SO4. The SEM photographs with the scale of 1 and 50 μm show the fly-ash particle is corroded by H2SO4 (indicated by arrow mark), and this may be due to dissolution of fly ash by H2SO4. The yields of 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines is more than 75% using this catalyst under microwave heating. All pyrazolines showed moderate activities against antimicrobial strains.ConclusionWe have developed an efficient catalytic method for synthesis of 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines by solid phase cyclization using a solvent-free environmentally greener catalyst fly ash: H2SO4 under microwave irradiation between aryl chalcones and hydrazine hydrate. This reaction protocol offers a simple, economical, environment friendly, non-hazardous, easier work-up procedure, and good yields. All synthesized pyrazoline derivatives showed moderate antimicrobial activities against bacterial and fungal strains.

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Background: This study aims to synthesis a series of (E)-N-(substituted benzylidene)-9-ethyl-9H-carbazole-3-amines, using solvent-free fly-ash:perchloric acid catalyst under microwave irradiation. To then characterize them using analytical, physical and spectroscopic data. Methods: Solvent-free microwave assisted (E)imines were adopted for the synthesis of (E)-N-(substituted benzylidene)-9-ethyl-9H-carbazole-3-amine, using fly-ash:perchloric acid as a catalyst. They were characterized by IR, NMR and mass spectroscopic data. The IR and NMR spectral data was correlated with substituent constants, F and R parameters using Hammett equation to study the effect of the substituents. Results: The yield of the synthesized imines were more than 75%. The spectral data of these (E)-N-(substituted benzylidene)-9-ethyl-9H-carbazole-3-amines had been correlated using single and multi-regression analysis. These gave a satisfactory or fair degree of correlation, with some parameters. Conclusion: Easy handling, non-hazardous and an environmentally safe method had been adopted for the synthesis of (E)-imines, using fly-ash:perchloric acid as catalyst, with better yields. Some of the Hammett spectral correlations were found to be satisfactory with the observed spectroscopic data.

Good yield of trifluoromethyl-imines have been synthesized by Fly-ash:H 2 SO 4 catalyzed condensation of anilines and phenyl trifluoromethyl ketone in microwave irradiation under solvent free conditions.

A series containing twelve substituted styryl 2-phenothiazenyl ketones have been synthesized. The electrochemical potentials of carbonyl and vinyl groups were measured. These potentials are correlated with Hammett substituent constants, F and R parameters. From the results of statistical analyses, the effects of substituent on the group reduction potentials have been discussed. The insect antifeedant activities of these chalcones have been studied using 4th instar larvae Achoea Janata L with castor leaf discs.

A series of Schiff’s bases have been synthesized by fly-ash:p-toluenesulfonic acid (fly-ash:PTS) catalyzed microwave assisted oxidative coupling of arylamines and substituted benzaldehydes under solvent-free condition. The synthesized Schiff’s bases are characterized by their physical constants, analytical and spectroscopic data. The group frequencies of imines such as IR (v, cm–1) and NMR (δ, ppm) spectral data was correlated with Hammett substituent constants, F and R parameters using single and multi-linear regression analysis. The antimicrobial activities of these Schiff’s bases have been studied using Bauer-Kirby method.