Studies on the cure parameters of cyanate ester–epoxy blend system through rheological property measurements

Thermosetting blend system of co-cured cyanate ester with epoxy resin is receiving importance for high technological applications because of its wide range of thermo-mechanical, rheological, and electrical properties. However, processing of these system warrant proper knowledge of the rheological behavior of the blend during the curing process. This article discusses the rheological behavior of the blend systems with respect to the pot life, gel time, gelation temperature and also evaluated fitting parameters for the prediction of gelation time and viscosity during the entire curing process from the isothermal rheological measurements.     

Crystal Structure of 3-[1-(4-Methylphenyl)-9,10-dihydro-4-azaphenanthren-3-yl]benzo[f]coumarin

Crystallography Reports - The crystal structure of the title compound is determined by single crystal X-ray structure analysis. The structure was solved by direct method and refined to a final...     

Aromatization and chemoselective alkylation of 1-methyl-3,4-dihydro-β-carboline-3-carboxylic acid and its derivatives

Unprecedented aromatization was observed during N-alkylation reactions of 1-methyl-3,4-dihydro-β-carboline-3-carboxylic acid methyl ester, giving rise to 9-alkyl-1-methyl-β-carboline-3-carboxylic acid methyl esters. Inverse addition of base during a similar reaction resulted in a chemoselective alkylation to form novel 3-butyl-1-methyl-3,4-dihydro-β-carboline-3-carboxylic acid methyl ester as the major product in good yield.     

Synthesis of some oxazolyl ‐ pyrazolyl; 1,4‐Dihydropyridinyl‐pyrazolyl and 1,2,3,4‐tetrahydro pyrimidinyl‐pyrazolyl coumarins

Various 3‐[1‐phenyl‐4‐(2‐substituted‐5‐oxo‐oxazol‐4‐ylidenemethyl) pyrazol‐3‐yl] coumarins 4a‐f ; 3‐[1‐phenyl‐4‐(2,6‐dimethyl‐3,5‐disubstituted‐1,4‐dihydropyridin‐4‐yl) pyrazol‐3‐yl] coumarins 5a‐f and 3‐[1‐phenyl‐4‐(6‐methyl‐5‐substituted‐2‐oxo‐1,2,3,4‐tetrahydropyrimidin‐4‐yl) pyrazol‐3‐yl] coumarins 6a‐f have been synthesized utilizing Erlenmyer‐Plochl reaction, Hantzsch reaction and Biginelli reaction respectively using 3‐(1‐phenyl‐4‐formyl‐pyrazol‐3‐yl) coumarins 3a‐c as a starting material.     

Synthesis of 1‐substituted 5‐aryl‐3‐(3‐coumarinyl)‐2‐pyrazolines by the reaction of 3‐aryl‐1‐(3‐coumarinyl)propen‐1‐ones with hydrazines

1‐Acetyl‐ and 1‐propionyl‐2‐pyrazolines 11‐27 have been synthesized by the reaction of (3‐coumarinyl)chalcones 1‐10 with hydrazine in hot acetic acid or propionic acid. While 5‐aryl‐3‐(3‐coumarinyl)‐1‐phenyl‐2‐pyrazolines 28‐35 have been prepared by the reaction of (3‐coumarinyl)chalcones 1,3,5‐10 with phenylhydrazine in hot pyridine. Structures of all new compounds have been elucidated by microanalyses, ¹H and ¹³C nmr spectroscopies.     

Efficient chemoselective alkylation of quinoline 2,4‐diol derivatives in water

Synthesis of various C‐3‐dialkyl derivatives of quinoline 2,4‐diol was achieved by condensation of aniline or substituted anilines with diethyl malonate, followed by chemoselective alkylation at C‐3 in water. The higher yields, easy work up and environmental compatible conditions are the main aspects of our method. J. Heterocyclic Chem., 2011.     

Synthesis and antimicrobial activity of some 7‐aryl‐5,6‐dihydro‐14‐aza[1]benzopyrano[3,4‐b]phenanthren‐8H‐ones

The title compounds, 7‐aryl‐5,6‐dihydro‐14‐aza[1]benzopyrano[3,4‐b]phenanthren‐8H‐ones 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l have been synthesized by reacting various 4‐hydroxy coumarins 1a , 1b , 1c with 2‐arylidene‐1‐tetralones 2a , 2b , 2c , 2d in the presence of ammonium acetate and acetic acid under Krohnke's reaction condition. The structures of all the synthesized compounds were supported by analytical, IR, ¹H‐NMR, and ¹³C‐NMR data. All the synthesized compounds 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l have been screened for their antibacterial activities against Escherichia coli (Gram ?ve bacteria), Bacillus subtilis (Gram +ve bacteria), and antifungal activity against Candida albicans (Fungi). J. Heterocyclic Chem., (2011).     

Anthranilic acid-formaldehyde polymers

Poly(anthranilic acid-formaldehyde)s (AFs) were prepared and characterized by IR spectroscopy, M^– _n, viscosity, and TGA. Polymeric metal chelates of AF samples with Cu²⁺, Co²⁺, Ni²⁺, Zn²⁺, Mn²⁺, and Cr²⁺ ions have been prepared and characterized. The electrical conductivity of polymeric chelates and iodine-doped polymeric chelates was studied over a temperature range of 35° to 100°C. From the electrical conductivity of these polymers, activation energies (E_a ) of electrical conduction were evaluated, and the electrical conductivity data of undoped and iodine-doped polymers were compared.