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Epoxide Ring (epoxide + ring)

Distribution by Scientific Domains
Chemistry100%

Selected Abstracts

An Efficient Synthesis of 2-Amino Alcohols by Silica Gel Catalyzed Opening of Epoxide Rings by Amines.

CHEMINFORM, Issue 37 2004
Asit K. Chakraborti
Abstract For Abstract see ChemInform Abstract in Full Text. [source]

Immobilization of Porphyrinatocopper Nanoparticles onto Activated Multi-Walled Carbon Nanotubes and a Study of its Catalytic Activity as an Efficient Heterogeneous Catalyst for a Click Approach to the Three-Component Synthesis of 1,2,3-Triazoles in Water

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 14-15 2009
Hashem Sharghi
Abstract An efficient, regioselective, one-pot and two-step synthesis of ,-hydroxy 1,4-disubstituted 1,2,3-triazoles from a wide range of non-activated terminal alkynes and epoxides and sodium azide by way of a three-component click reaction using a catalytic amount of [meso -tetrakis(o -chlorophenyl)porphyrinato]copper(II) (5,mol%) in excellent isolated yields is described. The reactions were performed in water as a green solvent at ambient temperature without any additives. By performing two reaction steps in one pot and purifying only at the final step, this procedure excludes any interim purification of in situ generated organic azide intermediates, which significantly improves the overall yield and reduces the reaction time. To benefit from the recovery and reuse of the catalyst, a new heterogeneous catalyst was prepared by simple and successful impregnation of the catalyst onto activated multi-walled carbon nanotubes (AMWCNT). The heterogeneous catalyst was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic forced microscopy (AFM), and thermogravimetric (TG) analysis to estimate the amount of nitrogen adsorption, and Raman and FT-IR spectroscopy. Leaching experiments after ten successive cycles showed that the catalyst is most strongly anchored to the AMWCNT support. Mechanistically, porphyrinatocopper catalyzes each step of the reaction in different ways as a bifunctional catalyst including epoxide ring opening by azide delivery to epoxide, forming in situ generated 2-azido alcohols followed by activation of the CC triple bond of the starting terminal alkynes by forming a porphyrinatocopper-acetylide intermediate and thereby promoting the [3+2]-cycloaddition reaction as the key step to form the triazole framework. [source]

2,3-Dihydro-3,3-dimethylspiro[1H -4-oxanthracene-5,2,-oxiran]-10(5H)-one

ACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2002
Vitor F. Ferreira
The central six-membered ring in the title compound, C16H16O3, is almost planar (and almost coplanar with the aromatic ring), despite one of its C atoms being formally sp3 hybridized. The planarity is a consequence of the C atom at the centre of the spiro­cyclic system also being part of the three-membered epoxide ring. The mol­ecules are linked by ,,­, and C,H,, interactions. [source]

Copolymerization of Cyclohexene Oxide with CO2 by Using Intramolecular Dinuclear Zinc Catalysts

CHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2005
Youli Xiao
Abstract The intramolecular dinuclear zinc complexes generated in situ from the reaction of multidentate semi-azacrown ether ligands with Et2Zn, followed by treatment with an alcohol additive, were found to promote the copolymerization of CO2 and cyclohexene oxide (CHO) with completely alternating polycarbonate selectivity and high efficiency. With this type of novel initiator, the copolymerization could be accomplished under mild conditions at 1 atm pressure of CO2, which represents a significant advantage over most catalytic systems developed for this reaction so far. The copolymerization reaction was demonstrated to be a living process as a result of the narrow polydispersities and the linear increase in the molecular weight with conversion of CHO. In addition, the solid-state structure of the dinuclear zinc complex was characterized by X-ray crystal structural analysis and can be considered as a model of the active catalyst. On the basis of the various efforts made to understand the mechanisms of the catalytic reaction, including MALDI-TOF mass analysis of the copolymers' end-groups, the effect of alcohol additives on the catalysis and CO2 pressure on the conversion of CHO, as well as the kinetic data gained from in situ IR spectroscopy, a plausible catalytic cycle for the present reaction system is outlined. The copolymerization is initiated by the insertion of CO2 into the ZnOEt bond to afford a carbonate,ester-bridged complex. The dinuclear zinc structure of the catalyst remains intact throughout the copolymerization. The bridged zinc centers may have a synergistic effect on the copolymerization reaction; one zinc center could activate the epoxide through its coordination and the second zinc atom may be responsible for carbonate propagation by nucleophilic attack by the carbonate ester on the back side of the cis -epoxide ring to afford the carbonate. The mechanistic implication of this is particularly important for future research into the design of efficient and practical catalysts for the copolymerization of epoxides with CO2. [source]