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  • 1
    Electronic Resource
    Electronic Resource
    Metal Ion Binding by Amino Acids. Potassium Hydrogen L-Glutamate Monohydrate K(L-GluH)·H2O (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 1001-1004 
    Details
    ISSN: 0009-2940
    Keywords: Amino acid complexes ; L-Glutamate complexes ; Hydrogen L-glutamate complexes ; Potassium hydrogen L-glutamate ; Hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The title compound is obtained by neutralization of aqueous solutions of L-glutamic acid with potassium hydroxide, and crystallization from aqueous methanol. The compound shows a pH of 7 in water at ambient temperature and an optical rotation [α]20D of -4.30 (c = 3.0). In the crystal (orthorhombic, space group P212121) the potassium ion is in a distorted trigonal-prismatic environment of six oxygen atoms of four different amino acids and of the water molecule. No nitrogen coordination is observed. Through the bridging function of some of the α-carboxylate oxygen atoms (O1, O2) and through complexation of the metal through the γ-carboxylate groups (O3), a layer-coordination polymer, with strings of potassium ions running parallel, is formed. The layers are cross-linked by hydrogen bonds involving the ammonium and γ-carboxylate functions as well as the water molecule.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901230512
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  • 2
    Electronic Resource
    Electronic Resource
    Synthetic pathways to disilylmethane, H3SiCH2SiH3, and methyldisilane, CH3SiH2SiH3 (1990)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 123 (1990), S. 2087-2091 
    Details
    ISSN: 0009-2940
    Keywords: Disilylmethane ; Methyldisilane ; Silanes ; Silicon carbide, hydrogenated, amorphous (a-SiC:H) ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Disilylmethane is available in a four-step synthesis starting with phenylsilane. This is converted into chlorophenylsilane by HCl/AlCl3. The reaction of PhSiH2Cl and dibromomethane with magnesium in tetrahydrofuran affords bis(phenylsilyl)-methane, which yields bis(bromosilyl)methane by treatment with anhydrous hydrogen bromide. (BrH2Si)2CH2 is converted into disilylmethane by reduction with LiAlH4 in a two-phase system using a phase-transfer catalyst. - Methyldisilane is available by alkylation of a monohalodisilane, XSi2H5 (X = Cl, Br), with methyllithium in a high-boiling ether or by silylation of bromomethylsilane with silylpotassium. Due to secondary silylation reactions the overall yields of methyldisilane are low in all cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19901231102
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  • 3
    Electronic Resource
    Electronic Resource
    A Synthetic Pathway to 1,3-Bis(trisilylmethyl)disiloxane [(H3Si)3CSiH2]2O  -  the Octasila Analogue of Dineopentyl Ether [(H3C)3CCH2]2O (1994)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 127 (1994), S. 1359-1362 
    Details
    ISSN: 0009-2940
    Keywords: Silanes ; Siloxanes ; Si - C bond, selective cleavage ; Arylsilylmethanes ; Si,C,O single-source CVD precursor ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A synthetic route to partly silylated tetra(silyl)methanes (ArH2Si)nC(SiH3)4  -  n′ to their precursors (TfH2Si)nC-(SiH2Ar)4  -  n (Ar = p-tolyl, phenyl; Tf = CF3SO3; n = 3, 2, 1), and to 1,3-bis(trisilylmethyl)disiloxane [(H3Si)3CSiH2]2O (9) is reported. Starting from symmetrical tetrakis(arylsilyl)-methanes (aryl = p-tolyl, phenyl), we have obtained the selectively dearylated (arylsilyl)silylmethanes (ArH2Si)nC(SiH3)4  -  n (Ar = p-tolyl, phenyl; n = 3, 2, 1) by Si - Ar cleavage with equivalent quantities of trifluoromethanesulfonic acid (triflic acid) and hydrogenation of the corresponding silyl triflates (TfH2Si)nC(SiH2Ar)4  -  n (n = 3, 2, 1) with LiAlH4. The synthesis of 9 has been accomplished by treating trisilyl(p-tolylsilyl)methane p-TolH2SiC(SiH3)3 (7) with stoichiometric amounts of triflic acid to give (trisilylmethyl)silyl triflate TfH2SiC(SiH3)3 (8) and hydrolysing the latter with water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19941270806
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  • 4
    Electronic Resource
    Electronic Resource
    Metal Ion Binding by Dipeptides: Structure of the Product Generated in “Aspartame” Hydrolysis, Sodium cyclo(L-α-Aspartyl-L-phenylalanine) Tetrahydrate, Na[c(L-Asp-L-Phe)] 4H2O (1991)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 124 (1991), S. 2743-2746 
    Details
    ISSN: 0009-2940
    Keywords: L-α-Aspartyl-L-phenylalanine, cyclisation of ; Dipeptides, cyclic ; Metal complexation by cyclic dipeptides ; Hydrogen bonding ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ester cleavage of aspartame (L-α-aspartyl-L-phenylalanine methyl ester, 1) by equimolar quantities of NaOH is accompanied by intramolecular cyclisation to sodium 3-benzyl-6-(carboxylatomethyl)-2,5-dioxopiperazine (2). The solid-state structure of the crystalline tetrahydrate has been determined by single-crystal X-ray diffraction analysis. The cations are arranged in strings, and each sodium atom is in a distorted octahedral environment of six oxygen atoms, including a β-carboxylato (O1) and an oxo function (O4) of two different dioxopiperazines and four water molecules. No nitrogen coordination is observed. Through the ligand bridging (O1, O4) of the metals and a set of hydrogen bonds involving the amide and carboxylate groups and all water molecules a three-dimensional network is established.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19911241216
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