Search results for "Oxime"
showing 10 items of 148 documents
Capillary column gas chromatographic identification of sugars in honey as trimethylsilyl derivatives.
1987
A method for identifying carbohydrates (mono-, di- and trisaccharides) in honey is presented. It is based on the separate preparation of both trimethylsilyl ethers and oxime trimethylsilyl ethers of the sugars followed by their gas chromatographic separation on a fused-silica capillary column coated with OV-101 using temperature programming. From the two chromatograms, the number of peaks given by each derivatized sugar, their relative retention times and peak-area ratios are used for identification. The identities of two unidentified trisaccharide peaks are considered. Quantitative applications to honey sugar analysis are discussed.
Synthesis, characterization and magnetic properties of mixed-valence iron complexes with 2-pyridyl oximes
2018
Two new mixed-valence iron complexes with 2-pyridyl oximes, [Fe(mpko)3Fe(H2O)2(NO3)](NO3)·2H2O (1) (mpko− = methyl(2-pyridyl)ketone oximate) and [{Fe(dpko)3}2Fe](ClO4)·4H2O (2) (dpko− = bis(2-pyridyl)ketone oximate), have been prepared by reaction of FeIII with mpkoH in methanol (1) and FeII with dpkoH in methanol/water (2). Dinuclear FeII(low-spin)FeIII(high-spin) and trinuclear FeII(low-spin)FeIII(high-spin)FeII(low-spin) cations are present in the crystal structure of 1 and 2, respectively. Intermolecular hydrogen bonds in 1 lead to weak antiferromagnetic interactions between pairs of neighboring FeIII centers, which allows observation of single-ion zero-field splitting effects.
Über umsetzungen an poly-p-lithiumstyrol. 4. Mitt. Darstellung carbonylgruppenhaltiger derivate des polystyrols
1961
In Fortsetzung fruherer Arbeiten wird die Reaktivitat von Poly-p-lithiumstyrol gegenuber solchen Agenzien gepruft, die zur Bildung von carbonylgruppenhaltigen Verbindungen fuhren. Wahrend bei der Umsetzung mit Orthoameisensaureester nur vernetzte Polymere entstechen, last sich mit Dimethylformamid ein losliches Derivat des Polystyrols herstellen das p-standige Formylgruppen tragt. Die Reaktion mit Nitrilen liefert polymere Ketone; mit Acetophenon entsteht Poly-p-vinylacetophenon, das mit dem aus dem Monomeren durch Polymerisation erhaltenen Produkt verglichen wird. Mit Benzonitril erhalt man Poly-p-vinylbenzophenon. Die polymeren Ketone konnen in die Oxime ubergefuhrt werden, deren Sticksto…
Cu(II), Ni(II) and Zn(II) mononuclear building blocks based on new polynucleating azomethine ligand : Synthesis and characterization
2017
Five new mononuclear complexes formed by the polynucleating ligand 2-[1-(3,5-dimethyl)pyrazolyl]-2-hydroxyimino-N′-[1-(2-pyridyl)ethylidene]acetohydrazide (HL): [Ni(L)(HL)]ClO4·2CH3OH (1), [Ni(L)2]·CH3OH (2), [Zn(L)(HL)]ClO4·2CH3OH (3), [Zn(L)2]·CH3OH (4) and [Cu(L)2]·CH3OH (5) were synthesized and characterized by elemental analysis, mass-spectrometry, IR-spectroscopy and X-ray analysis. The complexes reveal distorted octahedral N4O2 coordination arrangement formed by both protonated and deprotonated (1, 3) or two deprotonated ligand molecules (2, 4, 5). The presence of non-coordinated oxime and pyrazole groups resulted in the formation of extensive systems of hydrogen bonds in the crystal…
Co(II)-mediated synthesis of 2-carbamimidoylbenzoates and isoindole-1,3-diaminates
2015
Abstract Phthalonitrile, acetoxime and cobalt(II) nitrate hexahydrate are combined in acetone with formation of stable and easy to handle Co(II) complex [Co{C6H4C(NH2)NC(ONCMe2)2}2](NO3)2 (1). Interaction of 1 with excess alcohols ROH (also used as solvents) and 2 equiv of (NH4)2S leads, in one-step, to alkyl 2-carbamimidoylbenzoate nitrates [C6H4COOR{2-C(NH2)2}]NO3 [R=CH3, C2H5, C3H7, CH(CH3)2]. Similarly, N1,N3-dialkyl-1H-isoindole-1,3-diaminate nitrates [C6H4C(NR′)NC(NR′)]NO3 [R=C3H7, C4H9, C(CH3)3, CH2CH2OH, CH2CH2SC2H5) can be directly produced from 1 by its reaction with 4 equiv of amines and 2 equiv of (NH4)2S in alcoholic media.
ChemInform Abstract: Palladium-Catalyzed Suzuki Carbonylative Reaction of α-Halomethyl Oxime Ethers: A Regioselective Route to Unsymmetrical 1,3-Oxyi…
2015
ChemInform Abstract: Aza-Henry Reaction of Isatin Ketimines with Methyl 4-Nitrobutyrate en Route to Spiro[piperidine-3,3′-oxindoles].
2016
A new enantioselective route to spiro[piperidine-3,3′-oxindoles] from isatin ketimines is described. The aza-Henry reaction of N-Boc-isatin ketimines with methyl 4-nitrobutyrate in the presence of a Ph2BOX-CuBr2 complex provided the corresponding nitro amino esters with good diastereoselectivity and excellent enantioselectivity (up to >99% ee). The aza-Henry adducts were transformed into spiro[piperidine-3,3′-oxindoles] after reduction of the nitro group to oxime, and cleavage of the N-Boc group and lactamisation.
Aza-Henry Reaction of Isatin Ketimines with Methyl 4-Nitrobutyrate en Route to Spiro[piperidine-3,3′-oxindoles]
2015
A new enantioselective route to spiro[piperidine-3,3′-oxindoles] from isatin ketimines is described. The aza-Henry reaction of N-Boc-isatin ketimines with methyl 4-nitrobutyrate in the presence of a Ph2BOX-CuBr2 complex provided the corresponding nitro amino esters with good diastereoselectivity and excellent enantioselectivity (up to >99% ee). The aza-Henry adducts were transformed into spiro[piperidine-3,3′-oxindoles] after reduction of the nitro group to oxime, and cleavage of the N-Boc group and lactamisation.
Reaction Mechanism of an Intramolecular Oxime Transfer Reaction: A Computational Study
2014
Density functional theory (PBE0/def2-TZVPP) calculations in conjunction with a polarizable continuum model were used to assess the mechanism of the intramolecular oxime transfer reaction that leads to the formation of isoxazolines. Different diastereomers of the intermediates as well as different oximes (formaldehyde and acetone oxime) were considered. The computed reaction profile predicts the water-addition and -expulsion steps as the highest barriers along the pathway, a conclusion that is in line with the experimental evidence obtained previously for these reactions.