Fast and convenient synthesis of new symmetric pyrano[2,3-d:6,5-d']dipyrimidinones by an organocatalyzed annulation reaction
, Online first: December 2016
Mehdi Rimaz, Hossein Mousavi, Mojgan Behnam, Leila Sarvari and Behzad Khalili PDF (230 K)
Abstract: A fast and facile one-pot procedure for the preparation of symmetric 5-Aryloyl-1,9-dimethyl-5,9-dihydro-2H-pyrano[2,3-d:6,5-d']dipyrimidine-2,4,6,8(1H,3H,7H)-tetraone derivatives by two-component reaction of N-methylbarbituric acid and arylglyoxalmonohydrates catalyzed by DABCO in ethanol at 50 ºC is described. This protocol has the advantages of environmental friendless, very simple operation, high regio- and chemoselectivity and moderate to excellent yields.
Keywords: Pyranodipyrimidinones, DABCO, One-pot, Arylglyoxalmonohydrate
Hydrogel composite of poly(vinylalcool) with unmodified montmorillonite
, Online first: November 2016
Fatiha Reguieg, Nabahat Sahli and Mohamed Belbachir PDF (230 K)
Abstract: Crosslinked poly(vinylalcohol) (PVA) hydrogel composites based on algerian hydrophilic natural Na-montmorillonite (Na-MMT) nanoclay named Maghnite-Na (Mag-Na) were prepared in aqueous media, without utilization of chemical crosslinking agents, by repeated cycles of freezing and thawing. The morphology of hydrogel composites and their swelling in water at different amount of Mag-Na were investigated. The characterization of obtained hydrogel composites by X-ray diffraction (XRD) showed a remarkable increase of the basal distance of Mag-Na in PVA hydrogels. Therefore, Intercalated and exfoliated morphology was observed for prepared composites hydrogels of PVA. The infra-red (FTIR) characterization results showed that some interactions have been developed between the hydroxyl groups of PVA chains and Mag-Na in composite hydrogels. Introducing Mag-Na into PVA hydrogel affected their swelling. Increased amount of Mag-Na decreased the equilibrium degree of swelling and equilibrium water content.
Keywords: Hydrogel composite, PVA, Maghnite-Na, Freezing-thawing, Physical crosslinking
One-pot solvent free synthesis of dihydropyrimidinones using calcined Mg/Fe hydrotalcite catalys
, Online first: November 2016
Vijay V Dabholkar, Keshav S Badhe and Swapnil K Kurade PDF (230 K)
Abstract: The Mg/Fe = 3 hydrotalcite as reusable solid catalyst was found to be an excellent heterogeneous base catalyst for the synthesis of 3,4-dihydropyrimidinones/thiones, a multicomponent reaction using substituted aromatic aldehyde, ethyl acetoacetate and urea/thiourea. The work has been carried out under thermal solvent free conditions. Mg/Fe = 3 hydrotalcite heterogeneous solid catalyst offers simple means of recovery and the isolated catalyst was reused for number of times without significant loss of catalytic activity.
Keywords: Hydrotalcite, Dihydropyrimidinone, Aromatic aldehydes, Multicomponent reactions, Heterogeneous catalysis
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