Search results for "Ethylene"
showing 10 items of 2589 documents
ChemInform Abstract: Review: Solution Equilibria of Ternary Complexes Formed from Copper(II), Aliphatic Amines, and Bioligands
2014
This review provides a summary of the coordination chemistry of ligands in the ternary system: copper(II)–aliphatic amine–bioligand, where amine = ethylenediamine – En, diethylenetriamine – Dien, or N, N, N′, N″, N″-pentamethyldiethylenetriamine – Me5dien, and bioligand = selected amino acid, aminohydroxamic acid, or aminophosphonic acid, in aqueous solution. We would like to show the specific interactions of copper(II) in ternary systems in the context of complex equilibria chemistry.
Über die Autoxydation gesättigter makromolekularer Kohlenwasserstoffe
1973
Die Autoxydation in Losung von isotaktischem Polypropylen bzw. Polyputylen-1 gehorcht einer anderen kinetischen Beziehung als die entsprechende Autoxydation von ataktischem Polypropylen, Polybutylen-1 und Polyathylen. Die Autokatalyse der Autoxydation isotaktischer Produkte wird durch einen bimolekularen Kettenstart der gebildeten Hydroperoxyde hervorgerufen, wahrend bei ataktischen Produkten ein monomolekularer Kettenstart beobachtet wird. Die unterschiedliche Kinetik der Autoxydation kann eindeutig auf Taktizitatsunterschiede zuruckgefuhrt werden. The autoxidation of isotactic polypropylene and poly-butylene-1 in solution shows a kinetic difference from that of atactic fractions of these …
Evidence of a 1,4-dipole intermediate in the reaction of 1-phenyl-4-vinylpyrazole with ptad
1985
Abstract 1-Phenyl-4-vinylpyrazole reacts with 1-phenyl-1,2,4-triazoline-3,5-dione in methylene chloride to form an unstable azetidine (4). An intermediate 1,4-dipole is probably involved since, when the reaction is conducted in acetone, a 1:1:1 adduct (3) is isolated.
From Biocompatible to Biodegradable: Poly(Ethylene Glycol)s with Predetermined Breaking Points
2013
Poly(ethylene glycol) (PEG) is the gold standard polymer for biomedical applications. PEG is known for its biocompatibility and antifouling properties and is widely used for bioconjugation. However, like other synthetic polymers in the field, PEG is not biodegradable, limiting its use for parenteral formulations and protein conjugation to a molecular weight range with a specific upper limit (commonly 40–60 kDa) to avoid polyether accumulation in human tissue. For these biomedical applications, but also for other purposes such as cleavable hydrogels and templates for porous membranes, several routes for the insertion of in-chain biocleavable moieties, such as acetals or disulfides, into PEG …
Synthesis and biopharmaceutical characterisation of new poly(hydroxyethylaspartamide) copolymers as drug carriers.
2001
Abstract Four new poly(hydroxyethylaspartamide)-based copolymers bearing (a) poly(ethylene glycol) 2000, (b) poly(ethylene glycol) 5000, (c) poly(ethylene glycol) 2000 and hexadecylalkyl, (d) poly(ethylene glycol) 5000 and hexadecylalkyle, as pendant groups were synthesised. The copolymers were obtained by partial aminolysis of polysuccinimide with poly(ethylene glycol) and hexadecylalkyl amino derivatives followed by reaction with ethanolamine. Naked polyhydroxyaspartamide was obtained by polysuccinimide reaction with ethanolamine. The nuclear magnetic resonance, infrared, light scattering and elemental analysis allowed for the extensive physico-chemical characterisation of the carriers. T…
Boehmite Supported Pyrene Polyamine Systems as Probes for Iodide Recognition
2013
New organic–inorganic fluorescent probes made by attaching the tripodal polyamine (tris(2-aminoethyl))amine (tren), propylamine, or diethylenetriamine functionalized with pyrene as a fluorophore to an γ-aluminum oxohydroxide matrix have been prepared and studied both in solution and supported on the surface of boehmite nanoparticles. Both kinds of systems have been revealed as sensitive and selective fluorescence turn-off chemosensors for iodide in aqueous solution with an estimated detection limit that reaches 36 ppb. The recognition characteristics and photophysical properties of these molecules are essentially preserved when they are grafted to the surface of the particles. Since the nan…
Group 13 complexes of dipyridylmethane, a forgotten ligand in coordination chemistry.
2015
The reactions of dipyridylmethane (dpma) with group 13 trichlorides were investigated in 1 : 1 and 1 : 2 molar ratios using NMR spectroscopy and X-ray crystallography. With 1 : 1 stoichiometry and Et2O as solvent, reactions employing AlCl3 or GaCl3 gave mixtures of products with the salt [(dpma)2MCl2](+)[MCl4](-) (M = Al, Ga) as the main species. The corresponding reactions in 1 : 2 molar ratio gave similar mixtures but with [(dpma)MCl2](+)[MCl4](-) as the primary product. Pure salts [(dpma)AlCl2](+)[Cl](-) and [(dpma)AlCl2](+)[AlCl4](-) could be obtained by performing the reactions in CH3CN. In the case of InCl3, a neutral monoadduct (dpma)InCl3 formed regardless of the stoichiometry emplo…
Effect of ethylenediamine on the anodic stripping voltammetric determination of heavy metals in the presence of humic acid
1994
Ligand competition coupled with differential pulse anodic stripping voltammetry has been investigated for the determination of copper, lead and cadmium. Ethylenediamine displaces humic acid in its metal complexes forming kinetically labile compounds. It also eliminates interferences associated with the oxidation of copper. This enhances the sensitivity of the determination of the metals over a wide range of humic acid concentration (up to 30 mg/l). The procedure has been applied to the determination of heavy metals in a real water sample.
Poly(ethylene glycol) diacrylate based monolithic capillary columns for the analysis of polar small solutes by capillary electrochromatography
2018
Monolithic stationary phases based on poly(ethylene glycol) diacrylates for capillary electrochromatography were developed. Several poly(ethylene glycol) diacrylates (Mn 250, 575, and 700) were used as single monomers and the resulting columns were carefully compared. Methanol and ethyl ether were selected as porogenic solvents, and in all cases ultraviolet radiation was selected as initiation method to prepare polymeric monoliths. The influence of the monomer chain length and ratio monomer/porogen on the morphological and electrochromatographic properties of the resulting monoliths was investigated. Several families of compounds with different polarity (alkyl benzenes, organophosphorous pe…
Hybrid methacrylate monolithic columns containing magnetic nanoparticles for capillary electrochromatography
2015
Abstract Vinylized iron oxide magnetic nanoparticles (VMNPs) were incorporated into polymethacrylate monolithic columns to develop novel stationary phases with enhanced separation performance. The VMNPs were dispersed in a polymerization mixture containing gycidyl methacrylate and ethylene glycol dimethacrylate as monomers, cyclohexanol and 1-dodecanol as porogens and azobisisobutyronitrile as initiator. The stability of the VMNPs in the polymerization mixture was investigated at several VMNP contents. Using short UV-polymerization times, polymeric beds with homogenously dispersed VMNPs were obtained. The novel stationary phases were characterized by scanning electron microscopy. The chroma…