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11.
An efficient and environmentally friendly method preparing 2H-azirines in good yield has been achieved by microwave irradiation of vinyl azides in solvent free conditions. 相似文献
12.
An efficient method for the synthesis of enantiomerically pure (R)-phenylephrine hydrochloride 1 is described using a Sharpless asymmetric dihydroxylation as the key step. 相似文献
13.
Using radiotracer solutions of Hg (203Hg) and Os (185Os), techniques have been developed for sampling these elements presumably suitable for ion probe measurements. Mercury has been electrodeposited on the cross-sectional area (5 mm2) of an electrochemically pure Cu wire giving a recovery 25 to 30% at the tip. Similar efficiency is found for Hg distillate solutions. Osmium has been collected in a Ni–NiS bead after loading its thiourea complex solution on filter paper. The recovery in the bead is 80–90%. These methods should be of help for isotopic study of these elements by ion microprobe. The suitability of these samples for measurements remains unconfirmed. 相似文献
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15.
This paper presents a set of investigations on the binding of a metabolic inhibitor, azide with prosthetic heme group of biomolecules, hemin chloride (Hem) and cytochrome c (Cyt c) immobilized on Au and Ag nanoparticles. A variety of spectroscopic tools have been used to understand the chemistry occurring on the nanoparticle surface. While the nature of binding of the model system, hemin has been investigated by UV-visible, fluorescence, FTIR, and Raman spectroscopies, the azide binding has been studied in detail by MALDI-TOF MS. Hemin binding on the nanoparticle surface occurs through the carboxylic acid groups. The hemin-N(3) adduct on the nanoparticle surface has been detected by mass spectrometry and its fragments have been studied by post source decay analysis. The chemistry of hemin on the nanoparticle surface has been compared with that of the protein, Cyt c. Azide binding of Cyt c requires thermal activation due to reduced accessibility of the heme center, unlike in the case of hemin. The binding chemistry is similar for free Cyt c and Cyt c bound to the nanoparticles. 相似文献
16.
Ciprofloxacin-protected gold nanoparticles 总被引:3,自引:0,他引:3
Tom RT Suryanarayanan V Reddy PG Baskaran S Pradeep T 《Langmuir : the ACS journal of surfaces and colloids》2004,20(5):1909-1914
The antibacterial drug ciprofloxacin (cfH) has been used to protect gold nanoparticles of two different mean diameters, 4 and 20 nm. The protection is complete with about 65 and 585 cfH molecules covering 4 and 15 nm particles, respectively. The nature of binding has been investigated by several analytical techniques. The nitrogen atom of the NH moiety of piperazine group binds on the gold surface, as revealed by voltammetric and spectroscopic studies. The cfH-adsorbed particles are stable in the dry state as well as at room temperature, and as a result, redispersion is possible. The rate of release of the drug molecule from the nanoparticles is more in the basic medium than in pure water, and the kinetics depend on the size of the particle; faster desorption is seen in smaller particles. The bound cfH is fluorescent, and this property could be used in biological investigations. This study shows that metal nanoparticles could be useful carriers for cfH and fluoroquinolone molecules. Most of the bound molecules could be released over an extended period of time. 相似文献
17.
The diacetylenic adducts, Fe2(CO)6{-EC(H) = C(C CMe)E} (E = E, E E; E, E = S, Se, Te) (1–8) have been obtained from the room temperature stirring of Fe2(CO)6(-EE) with HC CC CMe in methanol solvent containing sodium acetate. Compounds 1–8 have been characterized by IR and multinuclear NMR (1H, 13C, 77Se, and l25Te) spectroscopy. Trends in the chemical shifts of 77Se and 125Te NMR spectra of Fe2(CO)6{-EC(H) = C(C CMe)E} with a variation of EE are discussed. 相似文献
18.
Robert Y. Ning Pradeep B. Madan Leo H. Sternbach 《Journal of heterocyclic chemistry》1974,11(2):107-111
Methods for the synthesis of the biologically active 7-acetyl-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one ( 6 ) are described. This includes two new methods for the preparation of 5-acetyl-2-aminobenzophenone ( 4 ). The crucial steps in these syntheses involve, respectively, the oxidation of an ethyl group to an acetyl group with permanganate or ceric ions ( 2 → 3; 5 → 6 ), the selective reaction of methyl lithium with the cyano group of 7-cyano-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one ( 8 ) and the efficient condensation of benzyl cyanide with the ethylene ketal of p-nitroacetophenone to form the anthranil 11 . 相似文献
19.
The oxidation of glycolic, lactic, malic, and a few substituted mandelic acids by 2,2′‐bipyridinium chlorochromate (BPCC) in dimethylsulphoxide leads to the formation of corresponding oxoacids. The reaction is first order each in BPCC and the hydroxy acids. The reaction is catalyzed by the hydrogen ions. The hydrogen ion dependence has the form: kobs = a + b [H+]. The oxidation of α‐deuteriomandelic acid exhibited a substantial primary kinetic isotope effect (kH/kd = 5.29 at 303 K). Oxidation of p‐methylmandelic acid was studied in 19 different organic solvents. The solvent effect has been analyzed by using Kamlet's and Swain's multiparametric equations. A mechanism involving a hydride ion transfer via a chromate ester is proposed. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 248–254, 2002 相似文献
20.
Bimal C. Dash Pradeep K. Tripathy Bikram K. Kanungo 《Monatshefte für Chemie / Chemical Monthly》1991,122(5):341-348
Summary Formation constants of mixed chelates with (trans-1,2-cyclohexylenedinitrilo)tetra-acetate (DCTA) as primary ligand and norleucinate (nle) as secondary ligand with metal ions La(III), Ce(III), Pr(III), Sm(III), Gd(III), Tb(III), Dy(III), Er(III), and Yb(III) have been determined by the modified potentiometricpH titration method of Irving-Rossotti in aqueous medium at (295±1) K and fixed ionic strength of =0.1M (NaClO4). Formation constants of binary complexes of the metal ions with the secondary ligand have also been determined under identical conditions. The mixed chelates were found to be more stable than the binary ones. The order of stabilities in terms of metal ions is La(III)Gd(III)
Gemischte Chelate einiger dreiwertiger Lanthanidenionen mit (trans-1,2-Cyclohexylendinitril)tetraacetat und Norleucinat
Zusammenfassung Es wurden die Komplexbildungskonstanten gemischter Chelate mit (trans-1,2-Cyclohexylendinitril)tetraacetat als Primärkomponente und Norleucinat als Sekundärkomponente mit den Metallionen La(III), Ce(III), Pr(III), Sm(III), Gd(III), Tb(III), Dy(III), Er(III) und Yb(III) mittels einer modifizierten potentiometrischen Titrationsmethode nach Irving-Rossotti in wäßrigem Medium bei (295±1) K und einer konstanten Ionenstärke von =0.1M (NaClO4) bestimmt. Die Bildungskonstanten der binären Komplexe der Metallionen mit dem Sekundärliganden wurden ebenfalls unter identen Bedingungen bestimmt. Es wurde festgestellt, daß die gemischten Chelate stabiler sind als die binären. Die Stabilitätsreihenfolge bezüglich der Metallionen ist La(III)Gd(III) 相似文献