[HDBU][HSO4]-catalyzed facile synthesis of new 1,2,3-triazole-tethered 2,3-dihydroquinazolin-4[1H]-one derivatives and their DPPH radical scavenging activity

Research on Chemical Intermediates - A simple and efficient protocol has been developed for the synthesis of new1,2,3-triazole-2,3-dihydroquinazolin-4[1H]-one (DHQ) conjugates(6a?j) via...     

Ojective ideals in modular lattices

The concept of an extending ideal in a modular lattice is introduced. A translation of module-theoretical concept of ojectivity (i.e. generalized relative injectivity) in the context of the lattice of ideals of a modular lattice is introduced. In a modular lattice satisfying a certain condition, a characterization is given for direct summands of an extending ideal to be mutually ojective. We define exchangeable decomposition and internal exchange property of an ideal in a modular lattice. It is shown that a finite decomposition of an extending ideal is exchangeable if and only if its summands are mutually ojective.     

Solvent-free sonochemical preparation of α-aminophosphonates catalyzed by 1-hexanesulphonic acid sodium salt

1-Hexanesulphonic acid sodium salt was found to be an efficient catalyst for the green synthesis of α-aminophosphonates by the coupling of aldehydes/ketone, an amine and triethyl phosphite under ultrasound irradiation at ambient temperature for appropriate time to furnish the desired product in good to excellent yield under solvent-free condition. This catalyst provides clean conversion; greater selectivity and easy workup make this protocol practical and economically attractive.     

An organocatalyzed facile and rapid access to α-hydroxy and α-amino phosphonates under conventional/ultrasound technique

In the present work, successful implementation of ultrasound irradiation for the rapid synthesis of α-hydroxy and α-amino phosphonates under solvent-free conditions is demonstrated. Use of a novel catalyst (i.e., camphor sulfonic acid) in combination with ultrasound technique is reported for the first time. Comparative study for the synthesis of α-hydroxy and α-amino phosphonates using conventional as well as ultrasonication method is discussed.     

Saccharomyces cerevisiae catalyzed one-pot three component synthesis of 2,3-diaryl-4-thiazolidinones

Saccharomyces cerevisiae (baker’s yeast) catalyzed one-pot three component cyclocondensation of aryl aldehydes, amines, and thioglycolic acid in organic medium leading to 2,3-diaryl 4-thiazolidinones has been carried out for the first time.     

l-Hexanesulphonic acid sodium salt promoted the one-pot synthesis of amidoalkyl naphthols under microwave-irradiation

Amidoalkyl naphthols have been synthesized in high yields in the presence of 1-hexanesulphonic acid sodium salt as an inexpensive solid catalyst under solvent-free conditions and microwave-irradiation.This catalyst provides clean conversion;greater selectivity and easy workup make this protocol practical and economically attractive.     

Effect of CuO addition on the optical and electrical properties of sodium zinc borophosphate glasses

Sodium borophosphate glasses doped with copper ions having general composition 20Na₂O-20ZnO-25B₂O₃-(35-x) P₂O₅-x CuO (x=1-8 mol %) were prepared using conventional melt-quench method and characterized by density, UV-visible optical absorption, photoluminescence and conductivity measurements. E_optical values for different glass samples are found to decrease systematically from 3.5 to 2.5 eV with increase in CuO content in the glass. Network modifying action of CuO with the glass network has been confirmed from the UV-visible optical absorption studies. Presence of Copper in the form of Cu⁺ species has been confirmed from photoluminescence measurements. The electrical conductivity (σ) increases with increase in copper oxide content in the glass and temperature dependence of electrical conductivity confirmed the semiconducting nature of the samples.     

Effect of sintering temperature and the particle size on the structural and magnetic properties of nanocrystalline Li0.5Fe2.5O4

Sintering temperature and particle size dependent structural and magnetic properties of lithium ferrite (Li_0.5Fe_2.5O₄) were synthesized and sintered at four different temperatures ranging from 875 to 1475 K in the step of 200 K. The sample sintered at 875 K was also treated for four different sintering times ranging from 4 to 16 h. Samples sintered at 1475 K have the cubic spinel structure with a small amount of α-Fe₂O₃ (hematite) and γ-Fe₂O₃ (maghemite). The samples sintered at≤1275 K do not show hematite and maghemite phases and the crystals form the single phase spinel structure with the cation ordering on octahedral sites. Particle size of lithium ferrite is in the range of 13-45 nm, and is depend on the sintering temperature and sintering time. The saturation magnetization increased from 45 to 76 emu/g and coercivity decreases from 151 to 139 Oe with an increase in particle size. Magnetization temperature curve recorded in ZFC and FC modes in an external magnetic field of 100 Oe. Typical blocking effects are observed below about 244 K. The dielectric constant increases with an increase in sintering temperature and particle size.     

Eco-friendly and facile synthesis of 2-substituted-1H-imidazo[4,5-b]pyridine in aqueous medium by air oxidation

We report a new environmentally-benign, convenient, and facile methodology for the synthesis of 2-substituted-1H-imidazo[4,5-b]pyridine. The reaction of 2,3-diaminopyridine with substituted aryl aldehydes in water under thermal conditions without the use of any oxidative reagent has been studied. The reaction has yielded 1H-imidazo[4,5-b]pyridine derivatives by an air oxidative cyclocondensation reaction in one step in an excellent yield. Furthermore, a series of compounds were synthesized and characterized by melting point, EI-MS, NMR, and IR tools. For comparison, the reference samples were prepared by the reported method. Utilization of aqueous medium, easy reaction conditions, isolation, and purification make this manipulation very interesting from an economic and environmental perspective.     

Nickel nanoparticle-catalyzed facile and efficient one-pot synthesis of polyhydroquinoline derivatives via Hantzsch condensation under solvent-free conditions

Polyhydroquinoline derivatives have been prepared efficiently in a one-pot synthesis via Hantzsch condensation using nanosized Nickel (Ni) as a heterogeneous catalyst. The present method does not involve any hazardous organic solvents or catalysts. The smaller size of Ni (80 ± 0.5 nm) having a higher surface to volume ratio has promising features for the reaction response such as the shortest reaction time, excellent product yields, simple work-up procedure, and purification of products by non-chromatographic methods.