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  • 1990-1994  (2)
  • 1960-1964  (2)
  • 1890-1899
  • 1992  (2)
  • 1964  (2)
  • Hydrolysis
  • 1
    ISSN: 1432-072X
    Keywords: Neisseria meningitidis ; Lipooligosaccharide ; Lipid A ; Polar substituents ; Hydrolysis ; Partial structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract On the basis of chemical and NMR data the partial structure of lipid A from lipooligosaccharide (LOS) of Neisseria meningitidis group B, strain BC5S No 125 was established. Lipid A consisted of disaccharide 2-deoxy-6-O-[2-deoxy-2-(3-hydroxytetradecanoylamino)-β-gluco-pyranosyl]-2-(3-hydroxytetradecanoylamino)-α-glucopyranose carrying the β-(2-aminoethyl)pyrophosphate residue at 0–4′ and the pyrophosphate or phosphate residue at 0–1. On hydrolysis of the acidic form of LOS with 1% acetic acid the substituent at 0–1 was practically completely removed whereas that at 0–4′ was stable. The analogous hydrolysis of the Mg-salt of LOS was accompanied by splitting off the pyrophosphate linkage in the substituent at 0–4′. Hydrolysis of LOS at pH 4.5 in the presence of SDS led mainly to a lipid A preparation retaining both pyrophosphate residues.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0749-1581
    Keywords: Platinum complexes ; 195Pt NMR ; 1H NMR ; Ethylenediamine ; Dimethylethylenediamine ; Tetramethylethylenediamine ; Hydrolysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The hydrolysis reactions of complexes of the type Pt(L)X2 where L is ethylenediamine (en), N,N- dimethylenediamine (N,N-Me2en), N,N-dimethylenediamine (N,N′-Me2en) and N,N,N′, N′-tetramethylethylenediamine (Me4en) were studied. The halo ligands were removed by precipitation with AgNO3 and the pH of the resulting filtrate, which was about 2, was adjusted to 5.8 (pD = 6.2). The study of the products formed was carried out by multinuclear NMR spectroscopy. The 195Pt NMR spectra showed the presence of several hydrolysed products, especially with en. The hydroxo-bridged dimer can be synthesized in a pure state with all the ligands except en. The results on the latter ligand contradict the published results on the synthesis of the en hydroxo-bridged dimer whose biological properties were studied. When Pt(L)I2 is used as starting material a small quantity of chloro species was always observed, indicating that the reactant contained a small quantity of Pt(L)ICI. The crystal structure of the [Pt(N,N-Me2en)(μ-OH)]2(NO3)2 dimer was determined. The compound belongs to the P21/c space group, with a = 8.262(5), b = 10.960(8), c = 11.405(8), β = 121.07(5)°, Z = 2 and ρcalc = 2.720 mg m-3. The results showed that this is the trans isomer with an inversion centre between the two Pt atoms. There is a considerable strain inside the four-membered ring, as shown by the reduced internal angles O—Pt—O′ = 79.1(6)0 and Pt—O—Pt′ = 101.0(6)°.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 47-54 
    ISSN: 0570-0833
    Keywords: Oxides ; Water ; High-pressure chemistry ; Hydrolysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reactions of the oxides SiO2, MoO3, and WO3 with steam at temperatures between 400 and 700 °C and pressures of 5 to 500 atm were studied by means of the transfer method. The results were evaluated by a new method. In the system Sio2/H2O the formation of gaseous Si(OH)4, Si2O(OH)6, and [SiO2(OH)2]x was found to occur in three different water-density ranges. In the systems MoO3/H2O and WO3/H2O the gaseous compounds MoO2(OH)2 and WO2(OH)2, which were already known, exist up to densities of approximately 0.05g/cm3. At higher densities, at which the supercritical phase begins to show the properties of a liquid to an ever increasing extent, isopolymolybdic or isopolytungstic acids appear.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0570-0833
    Keywords: Proton transfer ; Catalysis ; Enzyme catalysis ; Hydrolysis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The proton occupies a special position as a promoter and mediator in chemical reactions occurring in solution. Many reactions in organic chemistry are catalysed by acids or bases; likewise, most enzymes contain active groups which promote acid-base catalysis. To understand the reaction mechanisms involved, it is necessary to identify the elementary steps as well as their course in time. Systematic investigation of these elementary steps as well as their course in time. Systematic investigation of these elementary steps has become possible only with the development of new methods for studying very fast reactions. The present paper reviews the information obtained in this type of investigation. The result is a relatively complete picture of the elementary proton transfer mechanisms and a comprehensive description of the modes and laws of acid-base and enzymatic catalysis.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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