An efficient synthesis of 2,4,5-trisubstituted and 1,2,4,5-tetrasubstituted imidazoles by one-step condensation of  an aldehyde, benzil, ammonium acetate and primary amine in the presence of nanocrystalline magnesium aluminate under microwave irradiation is described. The advantages of this catalyst are including simple work-up, low cost and reusability. Compared with conventional methods, the ...

In this research, various polycyclic fused acridines were synthesized via the highly efficient and green one-step four-component reaction between isatins, dimedone, various amines, and dimethylacetylenedicarboxylates (DMAD/DEAD) in the presence of n-octyl-3-methylpipyridinium bromide ([OMePPy]+Br-) as a newly prepared ionic liquid, in absolute green situations at room temperature under solvent-...

the thermo-oxidative degradation of two viscous liquid resins of 1,2- poly-butadiene  (1,2-pbd) and 1,4- polybutadiene  (1,4-pbd) have been studied by differential scanning calorimetry (dsc) and thermogravimetry analy-sis  (tga). to  study  further,  the  effect of flm  thickness on oxidation kinetics was periodically studied by tracing the weight of the samples to make comparison with dsc resu...

background: echinophora platyloba dc (apiaceae) is one of the two endemic species of echinophora genus in iran. it has many folkloric uses and several biological activities but there is no information about its phytoconstituents. objective: in this work some of the secondary metabolites were isolated, purified and identified from n-hexane, ethyl acetate and methanol extracts from the aerial par...

Some aryl and heteroaryl azido compounds were synthesized from the reaction of corresponding fluoro and chloro compounds with sodium azide in DMF as solvent and under various reaction conditions especially ultrasonic irradiation. Reaction of aromatic and heteroaromatic azido compound with thioacetic acid in the presence of sodium hydrogen carbonate and in methanol as solvent led to the differen...

abstract the structural and electrostatic properties of the single-walled two representative (8, 0) zigzag and (4, 4) armchair models of pristine and gaas-doped on boron phosphide nanotubes (bpnts) was investigated by calculating the nuclear magnetic resonance tensors and with performing the density function theory. the geometrical structures of all representative pristine and gaas-doped models...

Compounds I, II and III, were used as models resembling gear systems (bods connecting CR3 groups to the skeletal molecule are parallel) in surveying the potential energy surface for their internal rotation. The magnitude of the barriers calculated for averaging the NMR signals, placed these compounds in the range of measurement accessible by dynamic NMR spectroscopy (which is cur...

The ion-pair association constant values, related to the reaction +  were determined by means of the NMR spectroscopy. The values of the thermodynamic functions of the ion pairing process were calculated on the basis of the NMR results. In addition, the association entropy was found to be dependent on the temperature. Comparing the experimental data and the Fuoss theory it is found that  ion-pa...

in this research, the characteristics of cmp dioxane lignin (hardwood origin) and soda bagasse lignin (ethanol soluble fraction) and dioxane lignin of bagasse were studied using gel permeation chromatography, gas chromatography-mass spectrometry and 13c nmr spectroscopy and dfrc degradation procedure. the results indicated that the main structural units in lignins are phenyl propane skeletons b...