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One-step Reaction (one-step + reaction)
Selected AbstractsPolyurethane- and Polystyrene-Supported 2,2,6,6-Tetramethyl- piperidine-1-oxyl (TEMPO); Facile Preparation, Catalytic Oxidation and Application in a Membrane ReactorADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2008Muhammad Afzal Subhani Abstract In this contribution, the facile synthesis of two new polymer-supported 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) catalysts and their application in the catalytic oxidation of alcohols to carbonyl compounds are described. For attachment of the TEMPO group to the polymer an isocyanate functionalized polymer is chosen. This new approach facilitates the synthesis in comparison with previously existing methods which generally require deprotonation of TEMPO prior to reaction with the polymer. Following this approach, polyurethane (PU)- and polystyrene (PS)-based TEMPO catalysts are prepared in a one-step reaction from commercially available compounds. Both polymer-supported catalysts showed promising yields for a variety of substrates using inorganic and/or organic co-oxidants in biphasic and/or monophasic systems. The recyclability of the corresponding catalysts was studied in repetitive batch experiments using filtration or distillation depending on the support type. Furthermore, application of the homogeneous polyurethane-supported TEMPO for the selective oxidation of benzyl alcohol in a continously operated membrane reactor is demonstrated. [source] Synthesis of amidocrownophanes with 27- and 28-membered rings and their molecular recognition toward urea and its derivativesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2005Kazuhisha Hiratani Novel crownophanes with 27- and 28-membered rings having two hydroxyl groups, two amide groups, and aromatic moieties such as naphthalene, pyridine, and phenyl rings were successfully synthesized by a one-step reaction from the corresponding macrocyclic polyethers via "tandem Claisen rearrengement" in moderate yields. They can solubilize urea and its derivatives into chloroform solution, while the corresponding macrocyclic polyethers do not solubilize them. According to NMR studies, crownophanes 1 and 2 interact with urea and its derivatives forming 1:1 complexes. [source] Solid phase peptide synthesis on epoxy-bearing methacrylate monolithsJOURNAL OF PEPTIDE SCIENCE, Issue 12 2004E. Vlakh Abstract Monoliths based on a copolymer of glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDMA) can be used directly as sorbents for affinity chromatography after solid phase peptide synthesis. The quality of the synthesized products, the amount of grown peptides on a support and the reproducibility of the process must be considered. A determination of the quantity of the introducing ,-Ala (and, consequently, the total amount of synthesized peptide) was carried out. Three peptides complementary to recombinant tissue plasminogen activator (t-PA) have been synthesized using Fmoc-chemistry on GMA-EDMA disks. The peptidyl ligands were analysed by amino acid analysis, ES-MS and HPLC methods. The affinity binding parameters were obtained from frontal elution data. The results were compared with those established for GMA-EDMA affinity sorbents formed by the immobilization of the same but separately synthesized and purified ligands. The immobilization on GMA-EDMA disks was realized using a one-step reaction between the amino groups of the synthetic ligand and the original epoxy groups of monolithic material. The affinity constants found for two kinds of sorbent did not vary significantly. Finally, the directly obtained affinity sorbents were tested for t-PA separation from a cellular supernatant. Copyright © 2004 European Peptide Society and John Wiley & Sons, Ltd. [source] GC separation of amino acid enantiomers via derivatization with heptafluorobutyl chloroformate and Chirasil- L -Val columnJOURNAL OF SEPARATION SCIENCE, JSS, Issue 22 2009Helena Zahradní Abstract Heptafluorobutyl chloroformate (HFBCF), a recently introduced derivatization reagent, was examined in enantioseparation of amino acids (AAs) by GC. Twenty proteinogenic AAs, plus ornithine, cystine and 4-fluorophenylalanine (internal standard) were treated with the reagent and separation properties of the derivatives were assessed on a Chirasil-Val capillary column. Nineteen AA enantiomers were efficiently separated in 43,min except proline, arginine and cystine. The HFBCF derivatives of the studied DL -AAs show improved separation over other chloroformate-based derivatives hitherto reported. A combination of the improved and faster separation with a simple derivatization protocol, involving an immediate one-step reaction,extraction in two-phase aqueous-organic medium, and low elution temperatures extend application of HFBCF to chiral AA analysis. [source] Synthesis and characteristics of novel chelate fiber containing amine and amidine groupsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2004Dong Hun Shin Abstract A polyacrylonitrile (PAN) fiber was adopted for the backbone of a chelate polymer and poly(acrylo-amidino ethylene amine) (PAEA) was prepared through a one-step reaction between the PAN fiber and ethylenediamine (EDA). The maximum removal capacity and degree of substitution were 7.8,meq per gram of dried PAEA and 98%, respectively. The PAEA was tested as an adsorbent in single and two-component metal aqueous solutions under changing pH. The Cu2+ ion accomplished maximum adsorption amount at pH 3 and the order of maximum adsorbed amounts on PAEA is Cu2+,>,Ag+,>,Zn2+,>,Ni2+,>,Pb2+ in molar basis. FT-IR spectroscopy was employed to characterize the chemical bonding in metal aqueous solutions and surface morphology was examined using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||