نتایج جستجو برای: epoxides
تعداد نتایج: 1664 فیلتر نتایج به سال:
New carotenoids, cryptocapsin-5,6-epoxide, 3'-deoxycapsanthin-5,6-epoxide, and cryptocapsin-5,8-epoxides, have been isolated from the ripe fruits of red mamey (Pouteria sapota). Cryptocapsin-5,6-epoxide was prepared by partial synthesis via epoxidation of cryptocapsin, and the (5R,6S)- and (5S,6R)-stereoisomers were identified by HPLC-ECD analysis. Spectroscopic data of the natural (anti) and s...
Thymidine was reacted in methanol with four epoxides of varying mutagenicities: propylene oxide, glycidol, epichlorohydrin and trichloropropylene oxide. A single product was detected with each epoxide, and these products had the same retention times on silica high pressure liquid chromatography (HPLC). UV spectra of the products identified them as 3-alkylthymidines, and this was confirmed by in...
The ring-opening copolymerization of epoxides with isothiocyanates (ITCs) is explored for the first time. In presence phosphazenium benzoxide, investigated in this work including propylene oxide, ethylene and cyclohexene oxide were successfully copolymerized both an aromatic ITC, phenyl isothiocyanate, two aliphatic ITCs, ethyl isothiocyanate hexyl isothiocyanate. Effects phosphazene bases used...
Different regioisomeric and diastereomeric isosorbide mono-epoxides are prepared polymerized to thermally stable relatively rigid biobased linear polyethers.
Enantiomerically pure epoxides and vicinal diols are key chiral synthons. Epoxide hydrolases (EHs) offer access to both chiral epoxides and vicinal diols and the development of a cost-effective technology based on EHs offers a compelling ‘green’ alternative to current asymmetric chemical technologies. This article describes the assumptions, innovations and developments that have allowed Oxyrane...
A highly sensitive fluorimetric procedure based on alkylation of nicotinamide is described for the determination of aliphatic epoxides. Subsequent reaction of the resulting N-alkylnicotinamides with a ketone in basic medium yields strongly fluorescent products after final acidification. Sensitivity of the assay is in the picomole range with good reproducibility. The alkylation reaction proceeds...
A regioselective high yielding monochloro substitution (chlorohydrin formation) via Mitsunobu reaction is reported. In carbohydrates and sterically hindered non-sugars, only the primary hydroxyl group is chlorinated, whereas in the non-sugar 1,2- and 1,3-alcohols, predominantly the secondary chloride substitution occurs. The versatile methodology provides indirect access to epoxides with the re...
Two new one-component aluminium-based catalysts for the reaction between epoxides and carbon dioxide have been prepared. The catalysts are composed of aluminium-salen chloride complexes with trialkylammonium groups directly attached to the aromatic rings of the salen ligand. With terminal epoxides, the catalysts induced the formation of cyclic carbonates under mild reaction conditions (25-35 °C...
This review deals with recent organo-catalyzed/initiated developments of co-polymerization cyclic anhydrides and epoxides to access polyesters.
a Veterinary Toxicology and Entomology Research Laboratory, Agricultural Research, Science and Education Administration, U.S. Department o f Agriculture, College Station, TX 77840, b Western Regional Research Laboratory, Agricultural Research, Science and Education Administration, U.S. Department o f Agriculture, Berkeley, CA 94710, and c Department o f Entomology, University o f California, Ri...
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