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  • 1
    Electronic Resource
    Electronic Resource
    Use of pyridine-2-aldehyde-2′-pyridylhydrazone for trace analysis of copper in foodstuffs (1976)
    Springer
    Microchimica acta 66 (1976), S. 505-513 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Pyridin-2-aldehyd-2′-pyridylhydrazon (PAPHY) reagiert mit Kupfer in wäßriger Lösung unter Bildung eines Mono- und eines Bis-Komplexes. Beide lassen sich mit Alkali deprotonieren und als neutrale Komplexe mitn-Amylalkohol extrahieren. Die intensiv gefärbten Chlor-PAPY-Cu(II)- und Bis-PAPY-Cu(II)-Komplexe zeigen Absorptionsmaxima bei 481 bzw. 455–460 nm in amylalkoholischer Lösung; für beide fehlen die Absorptionsbanden für N-H im IR-Spektrum. Mit überschüssigem PAPHY-Reagens werden Kupferspuren quantitativ als neutraler Bis-PAPY-Cu(II)-Komplex mitn-Amylalkohol extrahiert und dann durch Atomarabsorptionsmessung bestimmt. Kupferkonzentration und Atomarabsorption verhalten sich zueinander linear. Auf dieser Grundlage beruht die vorgelegte Methode zur Bestimmung von Kupferspuren in Nahrungsmitteln.
    Notes: Summary Pyridine-2-aldehyde-2′-pyridylhydrazone (PAPHY) reacts with copper in aqueous solutions to form a mono- and a bis-complex, both of which can be deprotonated with alkali and the neutral complexes can be extracted inton-amyl alcohol. The intensely coloured chloro-PAPY-copper(II) and bis-PAPY-copper(II) complexes show absorption maxima at 481 nm and 455–460 nm respectively inn-amyl alcohol solutions while both show the absence of absorption bands in their infrared spectra. By using excess of the PAPHY reagent, trace quantities of copper are extracted quantitatively as the neutral bis-PAPY-copper(II) complex inton-amyl alcohol and subsequently determined by atomic absorption measurement. A linear relationship exists between the copper concentrations and the atomic absorption readings. This forms the basis for the present method for trace analysis of copper in foodstuffs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01220108
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  • 2
    Electronic Resource
    Electronic Resource
    Mixed-ligand cobalt(III) complexes derived from bis(dehydroacetato)ethylenediimine (1986)
    Springer
    Transition metal chemistry 11 (1986), S. 453-458 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A hydroxocobalt(III) complex (1a), has been obtained by reaction of bis(dehydroacetato)ethylenediimine (H2dhaen) with cobalt(II) hydroxide or acetate in the presence of air. Addition of a second complexing agent leads to the formation of a series of mixed-ligand complexes (2)-(26) having either the trans- or cis-β configuration. In the cis-β complexes, the quadridentate ligand dhaen adopts a nonplanar conformation. Configurations are distinguishable from characteristic differences in the electronic and n.m.r. spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01386873
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  • 3
    Electronic Resource
    Electronic Resource
    Oxygenation of the cobalt(II) complex of an unsymmetrical bis-Schiff base (1990)
    Springer
    Transition metal chemistry 15 (1990), S. 459-464 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The cobalt(II) complex of an unsymmetrical bis-Schiff base. Co(dha, salen), has been prepared. In the presence of pyridine, it forms both monomeric superoxo and dimeric peroxo adducts with dioxygen. At −10°C and lower temperatures, the adduct formed in pyridine solution is mainly superoxo as shown by electronic and e.s.r. spectra as well as volumetric measurement of oxygen uptake. The solid adduct precipitated by addition of toluene is predominantly peroxo as shown by elemental analysis, i.r. spectrum, magnetic and thermogravimetric measurements. Comparison of the oxygen affinities of this complex and of the symmetrical Co(salen) is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01040776
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  • 4
    Electronic Resource
    Electronic Resource
    Unsymmetrical bis-Schiff bases derived from ethylenediamine, dehydroacetic acid and another aldehyde/Ketone and the preparation and characterisation of their copper(II) and nickel(II) complexes (1989)
    Springer
    Transition metal chemistry 14 (1989), S. 480-480 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01092595
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  • 5
    Electronic Resource
    Electronic Resource
    Unsymmetrical bis-Schiff bases derived from ethylenediamine, dehydroacetic acid and another aldehyde/ketone and the preparation and characterisation of their copper(II) and nickel(II) complexes (1988)
    Springer
    Transition metal chemistry 13 (1988), S. 64-68 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Partial displacement of the symmetrical bis-Schiff bases (1)–(4) of ethylenediamine and salicyladehyde, o-hydroxyacetophenone, acetylacetone or benzoylacetone by dehydroacetic acid have led to the formation and isolation of the unsymmetrical bis-Schiff base ligands (6)–(9). Attempted partial displacements of the symmetrical bis-Schiff base (5) of dehydroacetic acid or (1)–(4) by each of the other four carbonyl compounds have been unsuccessful. The Ni(II) and Cu(II) complexes of (6)–(9) have been prepared and characterized.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01041502
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  • 6
    Electronic Resource
    Electronic Resource
    Crystal structures of the nickel(II) and copper(II) complexes ofN,N′-bis(dehydroaceto)ethylenediimine (1985)
    Springer
    Transition metal chemistry 10 (1985), S. 375-379 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The nickel(II) and copper(II) complexes ofN,N′-bis(dehydroaceto) ethylenediimine are monomeric and hydrated. In both compounds, coordination occurs at the C(4) carbonyl of the dehydroacetic acid moiety. The Ni atom has square-planar geometry with a water molecule at a substantial distance away. Both structurally distinct Cu atoms have square-pyramidal geometry, the apical position of one being occupied by an oxygen atom of the C(2) carbonyl group in a neighbouring molecule, and that of the other by a water molecule which participates in hydrogen-bond formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00618846
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  • 7
    Electronic Resource
    Electronic Resource
    Catalytic autooxidation ofp-anisaldehyde and styrene by a cobaltbis-schiff base complex (1991)
    Springer
    Transition metal chemistry 16 (1991), S. 542-545 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The CoII complex derived from the unsymmetricalbis-Schiff base ligand, 3-[1-[[2-[[(2-hydroxyphenyl)methylene]-amino]ethyl]amino]ethylidene]-6-methyl-2H-pyran-2,4(3H) dione H2(dha, salen), is a catalyst for the autoxidation of aromatic aldehydes. Under ambient condition Co(dha, salen) catalyses the oxidation ofp-anisaldehyde top-anisic acid in quantitative yield (250 turnovers). The presence of Co(dha, salen) also accelerates the co-oxidation ofp-anisaldehyde and styrene (88 turnovers). In the co-oxidation process, styrene is selectively converted to styrene oxide as the major product.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01024327
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis and characterisation of copper(II), nickel(II) and palladium(II) complexes of some schiff bases of dehydroacetic acid (1984)
    Springer
    Transition metal chemistry 9 (1984), S. 390-395 
    Details
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Tri-and quadri-dentate Schiff bases have been synthesized from the reaction of dehydroacetic acid with diamines, aminoacids, aminophenols and aminoalcohols. The copper(II) and some nickel(II) and palladium(II) chelates of these ligands as well as copper(II) complexes of bidentate Schiff bases of dehydroacetic acid with anilines have been prepared and characterised by electronic, i.r. and n.m.r. spectral measurements and magnetic moments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00637026
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  • 9
    Electronic Resource
    Electronic Resource
    Intermolecular and intramolecular hydrogen bonding in 5-pyridylmethylenehydantoins: IR and NMR study (1991)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 4 (1991), S. 170-176 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The patterns of the NH stretching vibrations in the solid-state IR spectra of a series of 5-pyridylmethylenehydantoins revealed the presence of various modes of hydrogen bonding: intermolecular NH&4nldr; &4nldr;OC and intermolecular or intramolecular NH&4nldr; ‥‥N(py). These variations are related to the orientation of the pyridyl nitrogen and to stereochemistry. A distinction between intramolecularly and intermolecularly hydrogen-bonded compounds was also provided by comparison of the 1H NMR spectra in (CD3)2SO and in CDCl3.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610040308
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  • 10
    Electronic Resource
    Electronic Resource
    Z-E Isomerism of 5-cyclohexylmethylenehydantoins (1992)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 795-802 
    Details
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 5-Cyclohexylmethylenehydantoin and its 1- and 3-methyl derivatives were studied as the aliphatic analogues of the 5-benzylidenehydantoins to examine the effects of replacing a benzene by a cyclohexane ring on Z-E isomerism. The relative stabilities of the Z- and E-isomers were compared by estimating the free energy differences from thermal equilibration experiments and the heats of formation by AM1 calculation. In the Z-isomers, the possible existence of weakly attractive interaction between the C(4) = 0 and C(6)-H groups, which form parts of a stereochemically favourable, conjugated α,β-unsaturated system, is suggested as a contributory factor to the observed configurational preference. Assignment of configurations was based mainly on NMR and is supported by IR and UV spectra. NMR spectra also revealed the conformation of the cyclohexane ring and the cyclohexyl proton signals were assigned by double resonance and by high-field NMR in two solvents where solubility allows.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/poc.610051204
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