Search results for "Ethylene"

Soluble oligoaramide precursors--a novel class of building blocks for rod-coil architectures.

2005

A new synthetic route is described that allows the reversible conversion of the inherently insoluble oligo-p-benzamides into soluble materials through the formation of imidoyl chlorides. Syntheses of the corresponding dimer, trimer, and tetramer are reported; these compounds can easily be purified by crystallization and are accessible on the multigram scale. Structural proof was obtained by single-crystal X-ray structures of the trimer and tetramer precursors. They can be selectively functionalized into amides or esters at the terminal carboxylic acid group followed by hydrolysis of the imidoyl chlorides to the parent amides. This new class of compounds gives access to strongly aggregating …

Studien zum Vorgang der Wasserstoffübertragung, 45. Elektroreduktion aromatischer Carbonsäureester

1977

Bei der Elektroreduktion der Benzoesaureester 1 in Alkoholen an einer Quecksilberkathode mit quartare Ammoniumleitsalzen entsteht ein Gemisch von partiell kernhydrierten Reaktionsprodukten und Benzylalkohol (Tabelle 3). Elektroreduziert man jedoch in Gegenwart von Essigsaure, so wird die Kernhydrierung vollstandig unterdruckt und es entstehen ca. 70% Benzylalkohol (3) neben ca. 30% 1,2-Diphenylethylenglykol (9) als Hydrodimerem (Tabelle 4). Benzoesaure-phenylester (2h) wird nahezu ausschlieslich zu Benzylalkohol (3) elektroreduziert; Substituenten an der Benzoesaure (Verbindungen 2a-i) verandern diesen Reaktionsablauf nicht, wenn in Gegenwart von Essigsaure gearbeitet wird (Tabelle 8).Gleic…

1983

Poly(ethylene glycol)s grated onto suitably functionalized, crosslinked polystyrenes were introduced as a new class of multidetachably immobilized hydrophilic macromolecular supports for the synthesis of peptides. This new polymeric carrier system facilitates both the homogeneous solvation of the reaction site and the insolubilization of the substrate, which are prerequisites for an efficient multistep synthesis using polymeric supports. In these support systems, a strongly solvated hydrophilic linear chain molecule, poly(ethylene glycol) (PEG)1 , is attached to an insoluble, crosslinked polystyrene through suitable anchoring linkages. At the free chain end of this supported PEG, amino acid…

Influence of functionalization on interaction and drug release from α,β-polyaspartylhydrazide derivatives to a biomembrane model: evaluation by diffe…

2004

Abstract A comparative study on the ability of various polymers to interact with a biomembrane model was carried out by differential scanning calorimetry (DSC). The investigated samples were a water soluble polymer, the α,β-polyaspartylhydrazide (PAHy) and its derivatives containing polyethylene glycol (PEG2000) (sample PAHy–PEG2000), or hexadecylamine (C16) (sample PAHy–C16) or both compounds (sample PAHy–PEG2000–C16). Some samples are able to arrange themselves as micellar structures and to interact potentially with the membrane surface so as to favor the release of the drug near the target membrane and consequently to improve drug adsorption processes. First, the interaction of all polym…

Alkyl Complexes of Group 4 Metals Containing a Tridentate-Linked Amido−Cyclopentadienyl Ligand:  Synthesis, Structure, and Reactivity Including Ethyl…

1998

A series of group 4 metal complexes M(η5:η1:η1-C5Me4SiMe2NCH2CH2X)R2 (M = Ti; R = Me, CH2Ph; M = Zr, Hf; R = Me, Et, nPr, nBu, CH2Ph, CH2SiMe3, Ph) containing the tridentate-linked amido−tetramethy...

Intramuscular fatty acid composition of lambs given a tanniniferous diet with or without polyethylene glycol supplementation.

2007

The aim of this trial was to investigate the effects that dietary tannins have on lamb intramuscular fatty acids. Twenty-seven lambs were divided into three homogeneous groups: control group, receiving commercial concentrate based on maize; tannin group, fed a diet based on carob pulp (45% as fed basis); PEG group, receiving the same diet as the latter with addition of 42g/kg of polyethylene glycol (PEG, a binding agent that eliminates the effects of condensed tannins). The duration of the trial was 45 d. Intramuscular fatty acids were measured in the longissimus dorsi muscle. The isomer cis-9 trans-11 of linoleic acid (conjugated linoleic acid or CLA) and linolenic acid were higher in the …

Homogeneous ethylene-polymerization catalysts based on alkyl cations of the rare-earth metals: are dicationic mono(alkyl) complexes the active specie…

2003

Clicked and long spaced galactosyl- and lactosylcalix[4]arenes: New multivalent galectin-3 ligands

2014

Four novel calix[4]arene-based glycoclusters were synthesized by conjugating the saccharide units to the macrocyclic scaffold using the CuAAC reaction and using long and hydrophilic ethylene glycol spacers. Initially, two galactosylcalix[4]arenes were prepared starting from saccharide units and calixarene cores which differ in the relative dispositions of the alkyne and azido groups. Once the most convenient synthetic pathway was selected, two further lactosylcalix[4]arenes were obtained, one in the cone, the other one in the 1,3-alternate structure. Preliminary studies of the interactions of these novel glycocalixarenes with galectin-3 were carried out by using a lectin-functionalized chip…

Relationship between conformation and physicochemical properties of polypeptides. I. Synthesis of homo- and co-oligopeptides by the liquid-phase meth…

1980

The synthesis of the following oligo- and co-oligopeptides by the liquid-phase method is described: (L-Met)15 (I), [L-Glu(OBzl)]20 (II), (L-Val)8-Gly (IV), (L-Ile)8-Gly (V), (L-Ile)4-Gly-(L-Ile)4 (VI), (L-Ile)4-Pro-(L-Ile)4 (VII), (L-Met)5-L-Pro-(L-Met)5 (VIII), [L-Glu(OBzl)]7-L-Pro-[L-Glu(OBzl)]7 (IX). The oligomers are covalently bound to bifunctional polyethylene glycol (PEG) and monofunctional PEG-M of Mr 5 × 103−2 × 104. Analytical controls were carried out after each step of synthesis in order to ensure quantitative coupling yields. All products could be obtained in high purity as indicated by amino acid analysis, thin-layer chromatography and chiroptical methods. The solubility of th…

N,N,N-Alkyloctyldimethylammonium Chlorides in Water: A Thermodynamic Investigation

1993

Abstract Specific conductivities, densities, heat capacities and enthalpies of dilution at 298 K and osmotic coefficients at 310 K were measured for N,N,N -octylbutyldimethylammonium, N,N,N -octylpentyldimethylammonium, and N,N -dioctyldimethylammonium chlorides in water as functions of concentration. From the specific conductivity data, the CMC and the degree of the counterion dissociation have been calculated. It is shown that additional CH 2 groups in the variable alkyl chain affect both CMC and β less than they do in the single chain surfactants. The partial molar volumes, heat capacities, relative enthalpies, nonideal free energies, and entropies at 298 K were derived as functions of t…