4-(5-nonyl)pyridine extraction of platinum from different aqueous solutions

The partition of tracer-level (<10^?7 mole/l) platinum between various 4-(5-nonyl)-pyridine phases and aqueous nitric, hydrochloric, and sulphuric acid phases has been studied radiometrically as a function of the amine and acid concentrations. The effects of saltingout agents and some anions on the extraction of the metal are reported. The extraction data is compared with that of gold and conditions are established for the separation of daughter¹⁹⁹Au from neutron irradiated platinum. The distribution coefficients of various metal ions are given for the 4-(5-nonyl)pyridine-10M HCl system and their factors for separation from platinum estimated.     

Iron Carbonyls in Organic Synthesis,I. Iron Pentacarbonyl Induced Decomposition and Transfer Hydrogenation of Aryl Azides to Substituted Ureas

Iron pentacarbonyl catalyzes smooth decomposition of aryl azides in the presence of acetic acid to afford good (70–90°) yields of the corresponding disubstituted ureas. Possible and alternative reaction mechanism pathways are discussed.     

Raman scattering and optical absorption in S2N2 and partially polymerized S2N2 films

Raman scattering and optical absorption measurements between 0.5 and 5.0 eV on crystalline films of S₂N₂ and partly polymerized S₂N₂ have been made for the first time. The Raman active molecular and librational phonons have been observed and assigned. The Raman spectra of partly polymerized S₂N₂ show the appearance of weak scattering at 635 cm⁻¹ and appreciable broadening of the librational phonon peaks. Optical absorption maxima occur at 4.0 and 4.7 eV in pure S₂N₂ at 14 K, while absorptions at 0.86, 1.1 and 4 eV evolve with increasing polymerization.     

Studies on the sol-gel transformation of silicic acid sol in presence of dyes

The influence of dyes on the gelation of silicic acid sol has been studied with the help of viscometric and pH metric methods. The results indicate that the time of gelation decreases in presence of basic dyes and increases with acid dyes. It has also been found that methylene blue is adsorbed by replacement of H⁺ ions by the big cation of the dye followed by a possible combination between S of the dye and OH of the silanol group of silicic acid. The results on pH variations during gelation support this viewpoint. Similar results have been obtained with malachite green. The interaction of alizarin sulphonic acid with silicid acid is explained in terms of compound formation between the silanol and the phenolic groups while methyl orange undergoes orientation to quinonoid structure in presence of silicic acid. Positive adsorption is found to take place in all cases except methyl orange which is negatively adsorbed.     

Ab initio study on N,N′,N″‐triaminoguanidine

Electronic structure calculations and second‐order delocalizations in N,N′,N′′‐triaminoguanidine ( TAG ) have been studied by employing ab initio MO and density functional methods. There are total 10 rotational isomers on the potential energy (PE) surface of TAG . The effect of three amino groups substitution on guanidine ( Gu ) has been studied in terms of the primary and the secondary electron delocalizations in TAG by employing Natural Population Analysis (NPA). An increased electron delocalization is observed in protonated triaminoguanidine ( TAGP ) due to the three strong intramolecular hydrogen bonds and hence accounts for its extra stability. The increase in the electron delocalization upon protonation in TAG can be compared to that in guanidine. The absolute proton affinity (APA) of TAG is less than that of Gu . HOMA and NICS studies have been carried out to understand electron delocalization in TAGP . Copyright © 2007 John Wiley & Sons, Ltd.     

Comparative conventional and microwave assisted synthesis of heterocyclic oxadiazole analogues having enzymatic inhibition potential

A comparative microwave assisted and conventional synthetic strategies were applied to synthesize heterocyclic 1,3,4-oxadiazole analogues as active anti-enzymatic agents. Green synthesis of compound 1 was achieved by stirring 4-methoxybenzenesulfonyl chloride ( a ) and ethyl piperidine-4-carboxylate ( b ). Compound 1 was converted into respective hydrazide ( 2 ) by hydrazine and then into 1,3,4-oxadiazole ( 3 ) by CS₂ on reflux. The electrophiles, N-alkyl/aralkyl/aryl-2-bromopropanamides ( 6a–p ) were synthesized and converted to N-alkyl/aralkyl/aryl-2-propanamide derivatives ( 7a–p ) by reaction with 3 under green chemistry. Microwave assisted method was found to be effective relative to conventional method. ¹³C-NMR, ¹H-NMR and IR techniques were availed to corroborate structures of synthesized compounds and then subjected to screening against lipoxygenase (LOX), α-glucosidase, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. A number of compounds presented better potential against these enzymes. The most active compounds against LOX and α-glucosidase enzymes were subjected to molecular docking study to explore their interactions with the active sites of the enzymes.     

Entropy generation in electrical magnetohydrodynamic flow of Al2O3–Cu/H2O hybrid nanofluid with non-uniform heat flux

Journal of Thermal Analysis and Calorimetry - This paper explores the influence of entropy production on MHD hybrid nanofluid (Al2O3–Cu/H2O) flow due to permeable stretching sheet with...     

Chymotrypsin inhibitory constituents from Haloxylon recurvum

Haloxylase, the triglyceride (1), unsaturated fatty acid (2), and saturated fatty acid methyl ester (3) have been isolated from the chloroform-soluble fraction of Haloxylon recurvum. Their structures have been elucidated through spectroscopic studies and chemical transformation. All these compounds showed significant inhibitory activity against the enzyme chymotrypsin in a concentration dependent fashion.     

Tyrosinase inhibitory and antileishmanial constituents from the rhizomes of Paris polyphylla

The search for bioactive natural products from the rhizomes of Paris polyphylla (Trilliaceae) has resulted in the isolation of four known constituents, 1,5-dihydroxy-7-methoxy-3-methylanthraquinone (1), diosgenin-3-O-[alpha-L-rhamnopyranosyl-(1 --> 3)-beta-D-glucopyranoside] (2), diosgenin-3-O-[alpha-L-rhamnopyranosyl-(1(Rha) --> 2(Glu))-alpha-L-arabinofuranosyl-(1(Ara) --> 4(Glu))]-beta-D-glucopyranoside (3), and diosgenin-3-O-[alpha-L-rhamnopyranosyl-(1(Rha) --> 2(Glu))-alpha-L-rhamnopyranosyl-(1(Ara) --> 4(Glu))]-beta-D-glucopyranoside (4). Their structures were identified by spectral comparison with the reported data. Compound 1 was isolated for the first time from this genus. The chloroform, ethyl acetate, and butanol extracts of the plant were found to have mild to moderate inhibitory potentials against the enzyme tyrosinase. Compound 1 showed strong (IC(50) = 0.23 microM), while compounds 2-4 and hydrolyzed product 4a showed mild to moderate (IC(50) = 0.93-36.87 microM) activities against the tyrosinase. Similarly, compounds 2-4 and 4a showed mild to moderate (IC(50) = 1.59-83.72 microg mL(-1)) antileishmanial activities.     

New leishmanicidal physalins from Physalis minima

Two new physalins, 16,24-cyclo-13,14-secoergosta-2-ene-18,26-dioic acid-14 : 17,14 : 27-diepoxy-11beta,13,20,22-tetrahydroxy-5alpha-methoxy-1,15-dioxo-gamma-lactone delta-lactone (1), and 16,24-cyclo-13,14-secoergosta-2-ene-18,26-dioic acid-14 : 17,14 : 27-diepoxy-5alpha,11beta,13,20,22-pentahydroxy-1,6,15-trioxo-gamma-lactone delta-lactone (2), have been isolated from the whole plant of Physalis minima Linn. (var. indica). Their structures were deduced on the basis of spectroscopic analysis. Both of these compounds have shown potent leishmanicidal activity against the promastigotes of Leishmania major.