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  • 1
    Electronic Resource
    Electronic Resource
    Hydrogen-bonding interactions in the crystalline-phase structures of cinnamic acid derivatives (1999)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 55 (1999), S. 216-220 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Secondary interactions responsible for the crystalline-phase structures of various cinnamic acids and cinnamic acid esters drawn from the Cambridge Structural Database were studied with the help of the Cerius package implemented on an SGI workstation. Primarily hydrogen-bonding interactions were sought, but deviation from planarity was also measured. For the acids, the main structural feature is the strong hydrogen bonding between the carboxyl groups. The dimers are interconnected by C—H...O intermolecular hydrogen bonds. In most cases the C atom of the C—H unit was a member of the aromatic ring. Intramolecular (olefinic) C—H...O bonds were found to be frequent, fixing synperiplanar and antiperiplanar C=C—C=O conformations with about the same abundance in the acids and exclusively synperiplanar conformations in the esters. The carbonyl group of the ester is always involved in C—H...O hydrogen bonding. Here, the C atom of the C—H unit was either a member of the aromatic ring or the olefinic group, or was attached to the alcoholic O atom of the ester group. The β-phenyl and the carboxyl or the ester groups are almost coplanar. The crystals have a layered structure and in the most frequent parallel arrangement the phenyl groups are offset by varing amounts (but always to a small extent) in neighbouring layers. The common hydrogen bonds are mostly within a layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108768198011823
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  • 2
    Electronic Resource
    Electronic Resource
    Gas chromatographic-mass spectrometric determination of a phenylcinnamic acid isomers: Practical and theoretical aspects
    Amsterdam : Elsevier
    Journal of Chromatography A 668 (1994), S. 353-358 
    Details
    ISSN: 0021-9673
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0021-9673(94)80125-8
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  • 3
    Electronic Resource
    Electronic Resource
    Surface properties of fumed silica (Cab-O-Sil) and Cab-O-Sil-supported Pt and Cu catalysts, studied by ir spectroscopy
    Amsterdam : Elsevier
    Journal of Molecular Structure 293 (1993), S. 273-278 
    Details
    ISSN: 0022-2860
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0022-2860(93)80066-5
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  • 4
    Electronic Resource
    Electronic Resource
    Multiple steady state in the hydrogenative ring opening of propylcyclobutane over Rh/SiO2 (1997)
    Springer
    Catalysis letters 45 (1997), S. 193-195 
    Details
    ISSN: 1572-879X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract During the hydrogenative ring-opening reaction of propylcyclobutane over Rh/SiO2 bifurcation was observed. On varying the hydrogen concentration in the reactor a catalytic surface with two steady states was formed. This bistability was found over the ``working'' catalyst and was attributed to the interplay of adsorbed hydrogen, adsorbed propylcyclobutane, the carbonaceous deposits and the surface or close to surface Rh atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019080015419
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  • 5
    Electronic Resource
    Electronic Resource
    Thermal behaviour of montmorillonite pillared with different metal oxides (1993)
    Springer
    Journal of thermal analysis and calorimetry 39 (1993), S. 197-205 
    Details
    ISSN: 1572-8943
    Keywords: derivatograph ; IR spectroscopy ; montmorillonite ; pillared layer clays ; X-ray diffraction ; X-ray fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Natürliche Montmorillonite wurden durch verschiedene Polyhydroxy-Kationen gestützt. Die resultierenden gestützten Schichttonmaterialien (PILC) wurden mittels Röntgenfluoreszenz, Röntgendiffraktion und IR-Spektroskopie charakterisiert. Mittels einer Kombination von Röntgendiffraktion, Derivatographie und IR-Spektroskopie wurde das thermische Verhalten von Al-PILC im Detail beschrieben und ein Vergleich zu natürlichem Montmorillonit angestellt. Man fand, daß die Thermostabilität von Al-PILC geringer ist, als die von natürlichem Montmorillonit. Unabhängig davon hat eine Hitzebehandlung in der Stabilitätsregion ein signifikantes Sintern von natürlichem Montmorillonit zur Folge, während der Zwischenschichtabstand von Al-PILC stark beeinflußt wird.
    Notes: Abstract Natural montmorillonite was pillared by various polyhydroxy cations. The resulting pillared layer clays (PILCs) were characterized by X-ray fluorescence, X-ray diffraction (XRD) and infrared (IR) spectroscopies. The thermal behaviour of Al-PILC was investigated in detail by a combonation of XRD, derivatography IR spectroscopy and a comparison to natural montmorillonite is given. It was found that thermal stability of Al-PILC is lower than that of natural montmorillonite. However, heat treatment in the stability region results in significant sintering of natural montmorillonite, while the interlayer spacing of Al-PILC is hardly affected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01981732
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  • 6
    Electronic Resource
    Electronic Resource
    Amino Acid-Pillared Layered Double Hydroxide and Montmorillonite Thermal Characteristics (1999)
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 317-322 
    Details
    ISSN: 1572-8943
    Keywords: anionic and cationic intercalation of L-tyrosine ; DTG ; FT-IR ; Na-montmorillonite ; thermal behaviour ; Zn-Al hydrotalcite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Zn-Al hydrotalcite (HT) and Na-montmorillonite (Na-mont) were pillared by the deprotonated and the protonated forms of L-tyrosine, respectively. Pillaring was successful as the increased basal spacings due to intercalation attest. L-Tyr-HT proved to be thermally less stabile than HT, while that of L-Tyr-mont did not change compared to Na-mont. DTG curves showed more mass loss steps for the hosts than for the intercalated compounds. The extra steps belonged to the decomposition of the amino acid derivatives. FT-IR spectra of the samples pretreated in vacuum in the 293-773 K temperature range also showed that intercalation was successful and L-Tyr-HT is more temperature sensitive than L-Tyr-mont.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010190315865
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  • 7
    Electronic Resource
    Electronic Resource
    Polymorphic Transitions in Crystalline E- and Z-α-Phenylcinnamic acids followed by DSC (1998)
    Springer
    Journal of thermal analysis and calorimetry 53 (1998), S. 317-322 
    Details
    ISSN: 1572-8943
    Keywords: α-phenylcinnamic acid ; DSC ; polymorphic transitions ; stereoisomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Polymorphic transitions of α-phenylcinnamic acid stereoisomers crystallized from various solvents (CHCl3, ethanol, diethyl ether), precipitated with different acids (acetic acid or HCl) or sublimed have been studied by differential scanning calorimetry (DSC). Measurements were also supplemented by powder X-ray diffractometry (XRD). Polymorphic transitions were not found for any of the E isomer samples irrespective of the method of treatment. However, in heating-cooling cycles reversible transitions could be detected for the Z isomer. On heating an exothermic peak was registered on samples sublimed, crystallized from ethanol or diethyl ether before melting, while samples precipitated by HCl or crystallized from chloroform exhibited more complex transitions. Here, endothermic effects were also observed. Enthalpy values for transformations (either for melting or polymorphic and other transitions) are also given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010169116321
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  • 8
    Electronic Resource
    Electronic Resource
    Behaviour of Hydrotalcite and Its Fe (CN)64- Pillared Derivative on Heat Treatment (1999)
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 311-316 
    Details
    ISSN: 1572-8943
    Keywords: dehydration/rehydration and stability characterization ; Fe(CN)6 4- anion pillared layered double hydroxide ; Mg-Al layered double hydroxide ; thermal behaviour
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Mg-Al L(ayered) D(ouble) H(ydroxide) was prepared and its thermal behaviour was characterized by thermoanalytical methods (TG, DTG, DTA), 27Al M(agic) A(ngle) S(pinning) NMR spectroscopy, X-ray diffractometry (XRD) and S(canning) E(lectron) M(icroscopy). Heat treatment destroyed the layered structure, which could only be partially reconstituted by rehydration. On calcination mixed oxide with the predominance of basic sites were formed. Pillaring the LDH with Fe(CN)6 4- anions was also performed. The material was characterized by XRD and BET measurements. Heat stability of the pillared substance was investigated, too. Pillaring proved to be successful, however, decreased heat resistance was found in the intercalated material relative to the guest LDH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010138314956
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization of cationic pillared layer clays (1998)
    Springer
    Reaction kinetics and catalysis letters 64 (1998), S. 317-323 
    Details
    ISSN: 1588-2837
    Keywords: Pillared layer clays ; thermal characteristics ; surface acidity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Na-montmorillonite and its Al-, Ti-, Fe-, Cr-, Zr- and Sn-pillared derivatives (pillared layer clays) were prepared and characterized by instrumental methods and a chemical reaction. Structural characterization involved X-ray fluorescence (XRF) analysis, X-ray diffractometry (XRD),29Si and27Al MAS NMR spectroscopies, thermogravimetric (TG) and BET measurements. By the distinctly characteristic shapes of the d001 vs. temperature curves two groups could be distinguished, (i) Al-PILC, Ti-PILC, Cr-PILC, Zr-PILC and (ii) Fe-PILC, Sn-PILC, Na-montmorillonite. On montmorillonite isomerization of cyclopropane only occurred while oligomerization followed isomerization over Al-PILC. This latter reaction was attributed to Lewis and (the considerably smaller number of) Brönsted acid sites whose number, strength and accessibility increased due to pillaring.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02475351
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  • 10
    Electronic Resource
    Electronic Resource
    Modified montmorillonites as potential NO decomposition catalysts: Characterization by temperature-programmed reduction (1996)
    Springer
    Reaction kinetics and catalysis letters 58 (1996), S. 249-253 
    Details
    ISSN: 1588-2837
    Keywords: Montmorillonite ; ion exchange ; pillaring ; temperature-programmed reduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Na-montmorillonite has been modified by ion exchange of simple Fe3+ or Keggintype cations obtainedvia the partial hydrolysis of AlCl3 or the co-hydrolysis of AlCl3+FeCl2 mixture, in order to prepare catalysts for NO decomposition. Temperature-programmed reduction, the most important characterizing method in this work, revealed that isomorphous substitution of iron for aluminium was not feasible, instead, co-hydrolysis and co-pillaring occurred, resulting in Fe,Al mixed pillared clays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02067030
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