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51.
A simple catalytic system based on PdCl2 and triphenylphosphine chalcogenides (PPh3X; X = O, S, Se) is found to be highly effective (up to 97% isolated yield) in the room temperature Suzuki-Miyaura reactions. Under the same experimental conditions, triphenylphosphine chalcogenides as ligands show superior activities compared to free triphenylphosphine. 相似文献
52.
Manuel Temprado Maria Victoria Roux Archana R. Parameswar Alexei V. Demchenko James S. Chickos Joel F. Liebman 《Journal of Thermal Analysis and Calorimetry》2008,91(2):471-475
The present study reports a DSC study of the thio-and dithiocarbamates: 3H-benzoxazole-2-thione (2-mercaptobenzoxazole), 3H-benzothiazole-2-thione (2-mercaptobenzothiazole), thiazolidine-2-thione (2-mercapto-2-thiazoline), oxazolidine-2-thione (2-mercapto-2-oxazoline) and tetrahydro-1,3-oxazine-2-thione (5,6-dihydro-4H-1,3-oxazine-2-thiol) in the temperature interval T=268 K and the melting temperatures. Temperatures, enthalpies and entropies of fusion are reported. No solid-solid phase transitions were observed for the compounds in the temperature interval studied. The heat capacity of the compounds as a function of temperature was measured. 相似文献
53.
Derivatization of aromatic primary amines to N-allyl-N'-arylthioureas by reaction with allyl isothiocyanate and GC-MS of the derivatives, when pyrolysis to aryl isothiocyanates occurs in the heated injector, has been used to determine aromatic amines in the range 0.5-50 microg l(-1) with a correlation coefficient, r, in the range 0.9902-0.9992. The limit of detection ranged 8 to 30 ng l(-1) when 60 ml of sample were preconcentrated, after derivatization, on a styrene-divinylbenzene copolymer sorbent. The pyrolytic cleavage of sym- and unsym-diaryl or alkyl-/arylthioureas has been rationalized. The chromatography of isothiocyanates is much superior to that of aryl amines and the specific mass fragmentation permits positive identification of amines. The method has been applied to spiked drinking water, groundwater and river water samples, when the recovery ranged from 84 to 109% with RSD of 5-9%, and to detect aromatic amines formed by reductive cleavage of azo dyes in effluents when the recovery of amine was in the range 81-95% with RSD 8-15%. The method is not applicable to nitroanilines. 相似文献
54.
Singh Vinod P. Singh Archana Narang Krishan K. Bhattacharya D. 《Transition Metal Chemistry》2004,29(1):107-111
Complexes of the [AILCl2], [ML(OH)Cl] and [MLL(H2O)Cl] type, where HL = 5-bromouracil; HL = histidine; M = CrIII or FeIII and M = AlIII, CrIII or FeIII were synthesized and characterized. The complexes are polymers with high temperature decomposition points and are insoluble in H2O and common organic solvents. 5-Bromouracil is coordinated to the metal ion through the O atom of C(4)=O and the N atom of N(1), while histidine coordinates through the O atom of —CO2
– and the N atom of the —NH2 groups. The
eff values, electronic spectral bands and e.s.r. spectra suggest a polymeric six-coordinate spin-free octahedral stereochemistry for the CrIII and FeIII complexes. The in vivo antitumour effect of 5-bromouracil and its complexes was examined on C3H/He mice versus P815 murine mastocytoma. As is evident from their T/C values CrIII and FeIII complexes display significant and higher antitumour activity compared to 5-bromouracil while the AlIII complexes show lower activity. The in vitro results of the complexes on the same cells indicate that CrIII and FeIII complexes show higher inhibition on 3H-thymidine and 3H-uridine incorporation in DNA and RNA replication, respectively. 相似文献
55.
Marthakutty Joseph V. Suni Maliyeckal R. Prathapachandra Kurup Munirathinam Nethaji Archana Kishore Sarita G. Bhat 《Polyhedron》2004,23(18):3069-3080
Six new copper(II) complexes of 2-benzoylpyridine N(4)-cyclohexyl thiosemicarbazone (HL) have been synthesized and characterized by different physicochemical techniques like molar conductivity measurements, magnetic studies and electronic, infrared and EPR spectral studies. Five of the complexes have been found to possess the stoichiometry [CuLX], where X = Cl (1), Br (2), NO3 (3), NCS (4), N3 (5). The complex prepared from copper sulfate has the composition [Cu2L2SO4] · (H2O)2 (6). In all the complexes the deprotonated ligand, L and the anion were found to be coordinated to the Cu(II) ion. The terdentate nature of the ligand is evident from the IR spectra. The metal ligand bonding parameters evaluated from the EPR spectra indicate strong in-plane σ and in-plane π bonding. The magnetic and spectroscopic data indicate a square planar geometry for complexes 1, 3, 4 and 5, while the complexes 2 and 6 are assigned a square pyramidal geometry. Crystal structure of the complex [CuLCl] reveals two molecules per asymmetric unit of a monoclinic lattice, with space group symmetry P21/n. The complexes [ CuLBr 2] (2) and [CuLNCS] (4) crystallized into triclinic lattices with space group . Compound 2 exists as a thiolate bridged copper(II) dimer. The antimicrobial activity of the ligand and the copper complexes were tested against five types of bacteria isolated from clinical samples. The complexes were found to be active against Bacillus sp., Vibrio cholera O1, Staphylococcus aurus and Salmonella paratyphi. 相似文献
56.
P. C. Dwivedi Archana Srivastava R. S. Rathi 《Journal of polymer science. Part A, Polymer chemistry》1990,28(12):3279-3291
Polymerization of methyl methacrylate (MMA) with aliphatic primary amines and carbon tetrachloride has been investigated in th dimethylsulfoxide medium by employing a dilatometric technique at 60°C. The rate of polymerization (Rp) has been evaluated under the conditions, [CCl4]/[amine] < 1 and > 1. The kinetic data indicate possible participation of the charge transfer complexes formed between the amine + CCl4 and the amine + MMA in the polymerization of MMA. In the absence of CCl4 or amine, no polymerization of MMA was observed under the present experimental conditions. The polymerization of MMA was inhibited by hydroquinone, indicating a free radical initiation. The energy of activation varied from 32 to 58 kJ mol?1. 相似文献
57.
S. N. Bhadani Madhu Tewari Archana Agrawal K. Chandra Sekhar 《Fresenius' Journal of Analytical Chemistry》1994,349(6):478-481
A red, water-soluble complex of nickel with PAR can be extracted into chloroform with CTAB at pH 7.0. The system obeys Beer's law upto 0.5 g/ml with a molar absorptivity of 45 200 L·mol–1·cm–1 at 540 nm. Job's method of continuous variations revealed that the composition of the extracting species is 1:2:2 for nickel:PAR:CTAB. Based on this extraction, a highly sensitive and selective spectrophotometric method for the determination of nickel in polymetallic sea-bed nodules and in steels, after prior separation of iron and manganese, was developed. The standard deviation was 0.04–0.127 g for 5–25 g of nickel. 相似文献
58.
Archana S. Patole S. P. Patole Ji‐Beom Yoo Jeong‐Ho Ahn Tae‐Ho Kim 《Journal of Polymer Science.Polymer Physics》2009,47(15):1523-1529
The higher surface area of selectively grown multiwall carbon nanotubes (MWCNTs) and the better proximity of the reactant species in in situ microemulsion polymerization were used to attach the polystyrene (PS) nanoparticles to the outer wall of MWCNTs. Attachment were achieved by replacing surfactant with PS nanoparticles. SEM showed that the MWCNTs and PS nanoparticles were distributed in the composite. High resolution transmission electron microscopy showed successful anchoring of PS nanoparticles to the outer wall of the MWCNTs. In addition, anchoring enhanced the Raman's G/D ratio of the MWCNT and degradation temperature in PS nanoparticles. A mechanism of attachment of PS nanoparticles on the outer wall of MWCNT was proposed. The modified MWCNTs exhibited good durability and dispersability in different organic solvents. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1523–1529, 2009 相似文献
59.
UV–vis absorption, steady state and time resolved fluorescence studies on the photo physical behavior of indomethacin, a traditional NSAID in binary water ethanol mixtures have been presented. Our results reveal that indomethacin can sense the micro heterogeneity in the binary mixtures forming ground state fluorescent complex with two predominant types of clusters viz. ethanol self-association clusters and hydrogen bonded water clusters. 相似文献
60.
Ndonye RM Izmirian DP Dunn MF Yu KO Porcelli SA Khurana A Kronenberg M Richardson SK Howell AR 《The Journal of organic chemistry》2005,70(25):10260-10270
[structures: see text] The phytosphingosine-containing alpha-galactosylceramides (alpha-GalCers), KRN7000 and OCH, have been shown to activate NKT cells via interaction with CD1d, a member of the CD1 family of antigen presenting proteins. Evidence from KRN7000 stimulation of NKT cells suggests that alpha-GalCers may have applications in the treatment or prevention of a range of viral, bacterial, and autoimmune conditions. Moreover, OCH, a truncated analogue of KRN7000, appears to induce a T(H)2 bias, which could have implications for the treatment of autoimmune and inflammatory conditions. We have prepared the direct sphinganine-containing analogues of KRN7000 and OCH, 1 and 2, and found them to be comparable in activity to the parent compounds in inducing the release of IL-2, IL-4, and IFNgamma. In addition, compound 2 leads to a cytokine bias similar to that seen with OCH. This is significant because sphinganines are more easily accessed than phytosphingosines, which should facilitate SAR studies. 相似文献