An Unexpected Catalytic Synthesis of Novel and Known Bis(Pyrazolyl) Methanes by the use of α-aryl-N-phenyl Nitrones in Aqueous Media

Reaction of-aryl- N-phenyl nitrones with 3-methyl-1-phenyl-2-pyrazoline-5-one in the presence of a catalytic amount of silica tungstic acid in EtOH/H2O afforded, unexpectedly, high yields of bis(3-hydroxy-1-phenylpyrazolyl)-arylmethanes instead of the two possible 1,3-addition products. This is the first report of the synthesis of bis(3-hydroxy-1-phenylpyrazolyl)-arylmethanes via the reaction of nitrones and a pyrazolin-5-one. A possible mechanism for the process is suggested.

Graphene oxide nanosheets as metal-free catalysts in the three-component reactions based on aryl glyoxals to generate novel pyranocoumarins

Graphene oxide (GO) was employed as an efficient and powerful catalyst in one-pot, three-component synthesis of new pyranocoumarins.

New Conditions for the Effective Synthesis of Tri and Tetrasubstituted Imidazoles Catalysed by Recyclable Indium (III) Triflate and Magnesium Sulfate Heptahydrate

A one-pot three or four component reaction of wide range of aromatic aldehydes, benzil, aliphatic and aromatic primary amines and ammonium acetate is reported for the synthesis of tri/tetra-substituted imidazoles under solvent-free conditions. Indium (III) trifluoromethanesulfonate and magnesium sulfate heptahydrate as two highly efficient and recyclable catalysts perform a key factor to synthesis of imidazole derivatives with high yields.

Graphene oxide nanosheets promoted regioselective and green synthesis of new dicoumarols

Graphene oxide (GO) was obtained by modified Hummers oxidation of graphite and used as a highly efficient, metal-free, non-oxidative, and recyclable catalyst to promote the condensation of 4-hydroxycoumarin and aryl glyoxals for synthesis of new dicoumarols.

Silica tungstic acid as an efficient and reusable catalyst for the one-pot synthesis of 2-amino-4H-chromene derivatives

Silica tungstic acid (STA) has been found to be an efficient and reusable solid acid catalyst for the synthesis of 2-amino-4H-chromenes via the three-component reaction of aromatic aldehydes, malononitrile, and β-naphthol. STA as a novel solid acid was characterized by X-ray fluorescence, X-ray diffraction, and Fourier transform infrared spectroscopy.

Evaluation of metal pollution in fish and water collected from Gorgan coast of the Caspian Sea, Iran

In this study, concentrations of zinc, chromium, cadmium and lead were determined in water and three species of fish sampled from 10 selected stations along Gorgan coast using atomic absorption spectrophotometery, summer 2009. Mean lead levels in water and fish samples (119.50 ± 22.24 μg/L and 113.80 ± 33.11 μg/kg) were significantly higher than that of cadmium and chromium (p < 0.05). Cyprinus carpio had highest metals content than Mugila auratus and Rutilus frisikutum. The evaluated metals values in water collected from Gomishan wetland (Pb, Cd, Cr and Zn values are 145.31 ± 35.32, 120.46 ± 11.44, 96.47 ± 6.05 and 82.02 ± 34.37 μg/L, respectively) were higher than the other sampling sites. The result is consistent with the findings accessed by evaluation of the metals in fish specimens. The metals concentrations in the fish and water samples were below the recommended limits. But, elevating levels of metals in water and fish made a serious concern about ecosystem and food chain contamination.

A Rapid Synthesis of Some 1,4-aryldiazines by the Use of Lithium Chloride as an Effective Catalyst

The synthesis of some 1,4-aryldiazines (novel and known dibenzo[a,c]phenazines and quinoxalines) based on the condensation of 1,2-aryldiamines with aromatic 1,2-dicarbonyl compounds in the presence of lithium chloride as a heterogeneous catalyst is presented as convenient and efficient strategy. This method has advantages such as excellent yields, short reaction times, and simple work-up procedure.