نتایج جستجو برای: nmr and el_tofms
تعداد نتایج: 16839182 فیلتر نتایج به سال:
2-amino-substituted ketones react with α-methylene ketones under solvent-free conditions at 90 °c in thepresence of a catalytic amount of zirconium dodecylphosphonate to create the corresponding quinolinesin excellent yields. this procedure recommends numerous advantages such as easy work-up, use of mild,reusable and safe catalyst, short reaction timeand high yields. the new compounds have been...
The potential of tobacco waste as a viable source of medicinally important flavonoids like rutin has been investigated. Three flavonoids, apigenin, quercetin and rutin, have been isolated from waste tobacco leaves, and their identities have been confirmed by UV-visible, 1H-NMR and 13C-NMR spectroscopy. By using analytical HPLC, the amount of rutin present in the tobacco leaves, before and after...
nowadays nmr spectroscopy becomes a powerful tool in chemistry because of the nmr chemical shifts. hartree–fock theory and the gauge-including atomic orbital (giao) methods are used in the calculation of 29si nmr chemical shifts of various silicate species in the silicate solution as initial components for zeolite synthesis both in gas and solution phase. calculations have been performed at geo...
A mononuclear platinum(II) complex with two monodentate-S H4tg(-) ligands, [Pt(H4tg-κS)2(bpy)] (1), was newly synthesized by the reaction of [PtCl2(bpy)] (bpy = 2,2'-bipyridyl) with NaH4tg (NaH4tg =1-thio-β-d-glucose sodium salt) in water. Complex 1 reacted with additional [PtCl2(bpy)] in water to give an S-bridged dinuclear complex, [Pt2(μ2-H4tg-κ(1)S:κ(1)S)2(bpy)2](2+) ([2](2+)), in which a s...
A combination of X-ray crystallography, (6)Li, (15)N, and (13)C NMR spectroscopies, and density functional theory computations affords insight into the structures and reactivities of intervening aggregates underlying highly selective asymmetric alkylations of carboxylic acid dianions (enediolates) mediated by the dilithium salt of a C2-symmetric chiral tetraamine. Crystallography shows a trilit...
Molecular modeling analysis of charge density and heat of fornation by PM3 method as well as C, H NMR and 2D-NMR measurements of histidine (substrate) and some of its derivatives as histidine decarboxylase inhibitors were performed. It was established that the atom, usually nitrogen, which forms internal aldimine with pyridoxal5 -phosphate (PLP), (coenzyme), has negative and almost equal ...
background and objectives: the plants belonging to the genus heliotropium l. (boraginaceae) are the main sources of toxic pyrrolizidine alkaloids (pas). in the present study, we have investigated the pas of the aerial parts of heliotropium transoxanum bunge, a perennial species native to iran. methods: silica gel column chromatography and silica gel ptlc were applied for the isolation of pas pr...
A series of interesting sulfonamides containing hydroxyl group were synthesized under solvent-free conditions. The synthetic route involves the selective reaction of amino alcohol and sulfonating agents. The sulfonamides were obtained by simple procedure after an easy work-up in high yield and purity, and characterized by IR, 1H NMR and 13C NMR analysis. These compounds were tested for antibact...
Phytochemical investigation of the dichloromethane extract of the dried roots of Ferula badrakema resulted in the identification of one new and six known compounds. Known compounds were sesquiterpene coumarins: mogoltacin, feselol, badrakemin acetate, ferocaulidin, conferone and conferol acetate. The new compound was a sesquiterpene, named badrakemonin. The structures of these compounds were el...
bcn compounds have been researched theoretically and experimentally widely. in this paper, weintroduce the theoretical prediction of ternary b-c-n compounds. nmr spectroscopy was employedextensively to study these ternary nanostructures. we discuss the utilization of chemical shiftinformation as well as ab initio calculations of nuclear shielding for h20134c9n4 structuredetermination. we calcul...
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