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101.
J. S. Bradshaw J. Y. Hui Y. Chan B. L. Haymore R. M. Izatt J. J. Christensen 《Journal of heterocyclic chemistry》1974,11(1):45-49
Macroeyclic polyether sulfides have been prepared by reacting an oligoethylene glycol dichloride with a dimercaptan or sodium sulfide as reported in a previous paper (6). The following new compounds were prepared: 1,4,7-trithia(15-crown-5) (1); 1,4,10-trithia(15-crown-5) (II): 1,4,7,10-tetrathia(15-crown-5) (III); I-thia(18-crown-6) (IV); 1,4-dithia(18-crown-6) (V); 1,7-dithia(18-crown-6) (VI); 1,4,7-trithia(18-crown-6) (VII); 1,7-dithia(21-crown-7) (VIII); and 1,4,7-trithia(21-crown-7) (IX). The melting points of these and previously reported thia-crown compounds correlate with their structures. X-ray analyses of two thia-crown compounds indicate that the large sulfur atoms are directed away from the center of the ring. 相似文献
102.
2-Iodoaniline reacts with α,β-unsaturated carbonyl compounds in DMF at 100 °C in the presence of a catalytic amount of a palladium catalyst along with a base to afford the corresponding quinolones or quinolines in moderate to good yields. 相似文献
103.
Until recently, vascular endothelial growth factor (VEGF) was the only growth factor proven to be specific and critical for blood vessel formation. Other long-known factors, such as the fibroblast growth factors (FGFs), platelet-derived growth factor, or transforming growth factor-beta, had profound effects in endothelial cells. But such factors were nonspecific, in that they could act on many other cells, and it seemed unlikely that these growth factors would be effective targets for treatment of endothelial cell diseases. A recently discovered endothelial cell specific growth factor, angiopoietin, has greatly contributed to our understanding of the development, physiology, and pathology of endothelial cells (Davis et al., 1996; Yancopoulos et al., 2000). The recent studies that identified and characterized the physiological and pathological roles of angiopoietin have allowed us to widen and deepen our knowledge about blood vessel formation and vascular endothelial function. Therefore, in this review, we describe the biomedical significance of these endothelial cell growth factors, the angiopoietins, in the vascular system under normal and pathological states. 相似文献
104.
Salts of one isomeric form of the chloro-n-butylamine-, chloro-iso-butyl-amine- and chloro-sec-butylamine-bis(ethylenediamine)cobalt(III) cations have been prepared and characterised to have a cis-configuration (IR and VIS spectroscopy). Rate constants for their spontaneous aquation, mercury(II)-induced aquation and base hydrolysis have been determined and the activation parameters calculated. The results are compared with data obtained for the n-propylamine complex with a view to investigate the effects of methyl (α, β, γ) substituents on reactivities. The rate-determining dissociation of the outgoing group (Cl? or HgCl+) takes place via either a square-pyramidal or a trigonal-bipyramidal intermediate, depending on whether the activation entropy is negative or positive. 相似文献
105.
Light scattering and viscosity have been measured at 25°C. for dilute solutions of six unfractionated polyoxymethylene samples in the mixed solvent hexafluoroacetone–water (mole ratio 1/1.7) slightly buffered with triethylamine. Dialysis equilibrium through porous Vycor glass thimbles indicates that the polymer is strongly solvated by the hydrate (CF3)2C(OH)2, and this must be taken into account in evaluating weight-average molecular weights from the light-scattering data. Over the molecular weight range 23,000–185,000, the intrinsic viscosities (in deciliter per gram) follow the relation The corresponding unperturbed dimensions are σ = 2.3 ± 0.2 or r02/nl2 = 10.5 ± 1.5. 相似文献
106.
Mousumi Sannigrahi Patrick Pinto T.M. Chan Neng-Yang Shih F. George Njoroge 《Tetrahedron letters》2006,47(28):4877-4880
An efficient and practical synthesis of sterically hindered N-substituted lactams has been developed starting from simple starting materials. The stereochemistry of the synthetically useful N,N acetal intermediate has been established. 相似文献
107.
When metoprolol in methanol was analysed by capillary gas chromatography (GC), an additional peak was observed; mass spectrometry (MS) showed this additional peak to have a molecular weight 12 dalton higher than that of the parent compound. A similar phenomenon was observed with other beta-adrenergic blocking aryloxypropanolamines in methanol or dichloromethane. Capillary GC-MS using deuterated solvents as isotopic markers showed that a methylene group from the solvents was incorporated into the parent molecule. The structure of the observed products and the mechanism of their formation are proposed. 相似文献
108.
Kean H. Khoo K. Rodney Fernando Richard J. Fereday Chee-Yan Chan 《Journal of solution chemistry》1995,24(10):1039-1048
The solubility of thallium(I) chloride has been determined in aqueous solutions of strontium chloride and barium chloride at concentrations up to 1.5 mol kg–1. The data were analyzed using Pitzer's equations without making explicit assumption of association to ion pairs by assuming =3 instead of =2, with the (1) term for TlCl being equivalent to the (2) term for 2-2 electrolytes. Best values of (0) and (1) for TlCl are recommended together with K
s
, the activity solubility product. These were used to fit the present solubility data and derive the Pitzer model mixture parameters relevant to the systems, fTIN and fTINCl (N=Sr, Ba). Mixture parameters for TlCl+MCl+H2O systems are also derived to complete the parameter base. The fit of the experimental data was found to be worse when higher-order terms for asymmetrical mixing were included in the analysis. Activity coefficients for thallium(I) chloride in the mixtures are derived. 相似文献
109.
110.
Behaviour of electrolytes confined in cylindrical and slit pores are studied by computer simulations at the molecular level. Previous equilibrium and structural properties obtained by Monte Carlo techniques using the restrictive primitive model are discussed. Transport properties are calculated by the canonical molecular dynamics technique for ions with Lennard–Jones cores. Assuming an external electric potential, the chemical potential of individual ions can be balanced without the need for a grand canonical procedure. The mobility of the counterion is affected by the surface charge density. At a high surface charge, the mean square axial displacement of the counterion calculated is lower than the bulk value due to its high concentration near the charged wall. 相似文献