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Various Amines (various + amine)
Selected AbstractsPreparation of 5-nitro-2-amino[b]thiophenes and 1-(2-amino-5-nitrophenyl)ethanones via microwave irradiationJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2009Afsha Rais 1-(2-Chloro-5-nitrophenyl)ethanone) reacts with various amines in the presence of sulfur under microwave radiation to give the corresponding 2-aminobenzo[b]-thiophenes 3a,f in good yields. The yields of 3a,f are vastly superior to those obtained using conventional heating. Additionally, 1-(2-amino-5-nitrophenyl)ethanones 4a,f were also obtained. A mechanism is proposed in which 2-amino thiophenes 3a,f are formed by a SNAr mechanism involving an intramolecular addition of sulfur of the intermediate thioamide to the 2-substituted carbon to give a Meisenheimer complex, which collapses to 2-aminothiophenes 3a,f, and 2-amino ketones (4a,f) are formed by a parallel pathway involving nucleophilic addition amine to the 2-chloro position of 1 to form a Meisensheimer complex, which collapses to the amino ethanones. J. Heterocyclic Chem., (2009). [source] Polymerization of substituted acetylenes by various rhodium catalysts: Comparison of catalyst activity and effect of additivesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2005Atsushi Nakazato Abstract This research deals with comparison of the activity of various Rh catalysts in the polymerization of monosubstituted acetylenes and the effect of various amines used in conjunction with [Rh(nbd)Cl]2 in the polymerization of phenylacetylene. A zwitterionic Rh complex, Rh+(nbd)[(,6 -C6H5)B,(C6H5)3] (3), was able to polymerize phenylacetylene (5a), t -butylacetylene (5b), N -propargylhexanamide (5c) and n -hexyl propiolate (5d), and displayed higher activity than the other catalysts examined, that is [Rh(nbd)Cl]2 (1), [Rh(cod)(O - o -cresol)]2 (2), and Rh-vinyl complex (4). Monomers 5a and 5c polymerized virtually quantitatively or in fair yields with all these catalysts, while monomer 5b was polymerizable only with catalyts 3 and 4. Monomer 5d did not polymerize in high yields with these Rh complexes. The catalytic activity tended to decrease in the order of 3 > 4 > 2 > 1. Although polymerization of 5a did not proceed at all in toluene with [Rh(nbd)Cl]2 alone, it smoothly polymerized in the presence of various amines as cocatalysts. The polymerization rate as well as the molecular weight of polymer depended on the basicity and steric bulkiness of amines. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4530,4536, 2005 [source] Magnetically Separable Gold Catalyst for the Aerobic Oxidation of AminesCHEMCATCHEM, Issue 1 2009Linda Aschwanden Abstract A magnetically separable, recyclable gold catalyst consisting of gold nanoparticles supported on intimately mixed superparamagnetic ceria/iron oxide has been prepared by simple addition of the preformed mixed oxide support and the gold precursor, Au(OAc)3, to the reaction mixture of the aerobic oxidation of amines. The catalyst was characterized by means of X-ray diffraction (XRD), N2 adsorption, superconducting quantum-interference device (SQUID) measurements, time-of-flight secondary ion mass spectrometry (TOF-SIMS), scanning transmission electron microscopy (STEM), and scanning electron microscopy with an energy-dispersive X-ray spectrometer (SEM-EDAX). Catalytic tests with various amines showed high selectivity to the corresponding imines (87,100,%), and good separation efficiency and recyclability of the catalyst. [source] Guest-dependent conformation of 18-crown-6 tetracarboxylic acid: Relation to chiral separation of racemic amino acidsCHIRALITY, Issue 7 2008Hiroomi Nagata Abstract (+)-18-Crown-6 tetracarboxylic acid (18C6H4) has been used as a chiral selector for various amines and amino acids. To further clarify the structural scaffold of 18C6H4 for chiral separation, single crystal X-ray analysis of its glycine+ (1), H3O+ (2), H5O (3), NH (4), and 2CH3NH (5) complexes was performed and the guest-dependent conformation of 18C6H4 was investigated. The crown ether ring of 18C6H4 in 3, 4, and 5 took a symmetrical C2 or C2 -like conformation, whereas that in 1 and 2 took an asymmetric C1 conformation, which is commonly observed in complexes with various optically active amino acids. The overall survey of the present and related complexes suggests that the molecular conformation of 18C6H4 is freely changeable within an allowable range, depending on the molecular shape and interaction mode with the cationic guest. On the basis of the present results, we propose the allowable conformational variation of 18C6H4 and a possible transition pathway from its primary conformation to the conformation suitable for chiral separation of racemic amines and amino acids. Chirality, 2008. © 2008 Wiley-Liss, Inc. [source] | ||||||||||