Search results for "Ethylene"

Efficient Synthesis of 1,4,7-Triazacyclononane and 1,4,7-Triazacyclononane-Based Bifunctional Chelators for Bioconjugation

2014

The reaction of diethylenetriamine with chloroacetaldehyde yielded a bicyclic aminal intermediate for the synthesis of 1,4,7-triazacyclononane (TACN), a macrocyclic polyamine the derivatives of which find applications as catalysts, bleaching agents, and chelators for medical imaging. This new synthetic protocol outperforms the synthetic methods described so far because it does not involve any cyclization step. Moreover, this aminal intermediate allowed access to a new family of TACN derivatives functionalized on the carbon skeleton, for example, C-aminomethyl-TACN. This novel compound is a precursor of valuable bifunctional chelating agents for nuclear medicine, in particular, for the prepa…

Der nachweis der kettenstruktur von aus p-kresol und formaldehyd aufgebauten mehrkernverbindungen. I. Durch verschiedene synthese und identifizierung…

1962

In ubersichtlicher, mehrfacher Synthese werden homologe Mehrkernverbindungen aufgebaut, die aus uber Methylenbrucken verbundenen p-Kresolbausteinen bestehen (Novolak-Struktur). Die verschiedenen, zu einer Mehrkernverbindung fuhrenden Synthesen geben identische Verbindungen. Die Kettenstruktur dieser Mehrkernverbindungen kann durch kettenanaloge Enthalogenierungen, durch geeignete Kondensationen (Gl. (1)) sowie durch entsprechende Substitutionsbanden in den IR-Spektren der Verbindungen nachgewiesen werden. By means of rational, multiple syntheses, homologous polynuclear compounds were prepared, consisting of p-cresol units linked by methylene bridges (Novolac structure). The different ways o…

The Number of Active Sites for the Polymerization of Ethylene, Propylene and Butene-1 by Ziegler-Natta Catalyst

1975

ChemInform Abstract: Chemical Compounds and Toxicological Assessments of Drinking Water Stored in Polyethylene Terephthalate (PET) Bottles: A Source …

2012

A declaration of conformity according to European regulation No. 10/2011 is required to ensure the safety of plastic materials in contact with foodstuffs. This regulation established a positive list of substances that are authorized for use in plastic materials. Some compounds are subject to restrictions and/or specifications according to their toxicological data. Despite this, the analysis of PET reveals some non-intentionally added substances (NIAS) produced by authorized initial reactants and additives. Genotoxic and estrogenic activities in PET-bottled water have been reported. Chemical mixtures in bottled water have been suggested as the source of these toxicological effects. Furthermo…

Versuche zur umsetzung von methylendiphenolen mit glucosederivaten und zur kondensation von O-phenylglucosidderivaten

1981

Attempts to apply known methods of glucosidation to oligo[(hydroxyphenylene)methylene]s were not satisfying. The reaction of 4,4'-dimethyl-2,2'-methylenediphenol (1a) with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide gave a monoglucoside in 11% yield. A second attempt, the condensation of suitable O-phenylglucoside derivatives was unsuccessful. From a series of O-phenylglucosides (4) only 4-(2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyloxy)benzylbromide could be condensed with O-(4-hydroxymethylphenyl)-2,3,4,6-tetra-O-acetylglucopyranose to the corresponding diglucoside of 4,4'-oxydimethylenediphenol (7). Condensation reactions of the O-phenylglucoside 4k, to obtain an O-glucosidized poly[…

Synthesis of azamacrocycles via a Mitsunobu reaction

2005

Reaction of pernosylated diethylenetriamine and 2-substituted propane-1,3-diols in dry THF in the presence of triphenylphosphine and diisopropyl azodicarboxylate gives the corresponding protected 9-substituted 1,4,7-triazacyclodecanes. The Mitsunobu reaction was also used in the preparation of 3-substituted 1,5,9-triazacyclododecanes and macrocyclic pyridine derivatives.

Kristallisation und schmelzverhalten von fraktionen verzweigten polyethylens, 1. Darstellung und charakterisierung der fraktionen

1983

A branched polyethylene with broad molecular weight distribution was separated into a series of fractions by fractional precipitation from dilute solution. The fractions were characterized by viscometric and density measurements, IR-spectroscopy and calorimetry. The methyl group content and the density turned out as largely constant. Molecular weight effects show up in the melting behaviour. The main range of melting and the end of the melting curve shift to lower temperatures with decreasing molecular weight. Compared to the overall extension of the melting range these shifts are small. One has to conclude that polydispersity gives only a minor contribution to the broadening of the melting…

H2-Antihistaminika, 8. Mitt. Synthese potentieller H2-Antihistaminika der Ethylendiamin-Reihe

1982

Als potentielle H2-Antihistaminika wurden die Ethylendiaminderivate 8,9 und 13 dargestellt und auf ihre H2-antihistaminische Wirksamkeit untersucht. H2-Antihistaminics, VIII: Synthesis of Potential H2-Antihistaminics with Ethylenediamine Structure As potential H2-antihistaminics, the ethylenediamine derivatives 8,9 and 13 were prepared and tested for their H2-antihistaminic activity.

Ground and excited state properties of polyamine chains bearing two terminal naphthalene units

2002

A series of compounds bearing two naphthalene units linked through methylene groups to both ends of different open-chain polyamines has been investigated. The fluorescence emission studies show the presence of an excimer species whose formation depends on the protonation state and length of the polyamine chains and implies the existence of a bending movement in the excited state allowing the two naphthalene units to approach and interact. This interpretation was clearly proven by time-resolved fluorescence with the appearance of double exponential decays with a rise time observed at the excimer emission wavelength. For comparison purposes one bis-chromophoric compound containing a rigid cha…

Umsetzungen von polyacroleinen mit formaldehyd. Polymere acroleine. 28. Mitt.1

1963

Polyacroleine wurden in wasriger Suspension und in einem Pyridin-Wasser-Gemisch in Anwesenheit von basischen Katalysatoren mit Formaldehyd umgesetzt. Die Reaktions-produkte enthalten, in Abhangigkeit von den Versuchsbedingungen, neben Carboxylgruppen hauptsachlich primare Alkoholgruppen. Die chemischen Eigenschaften und Vergleiche mit polymeren Modellsubstanzen lassen darauf schliesen, das die gewonnenen Polymeren im wesentlichen aus Methylen-propandiol-1,3-Grundbausteinen aufgebaut sind. Polyacroleins were reacted with formaldehyde in aqueous suspension and in a pyridin water mixture in the presence of basic catalysts. Depending on the experimental conditions the products of the reaction m…