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81Author    Franz Kalchsclimid, Erwin MayerRequires cookie*
 Title    Bildung von Alkylcarbenium-Ionen im System Aluminium-(Gallium-)halogenid/Halogenwasserstoff Formation of Alkylcarbenium Ions in the System Aluminium (Gallium) Halide/ Hydrogen Halide  
 Abstract    The tert-butyl cation is formed in the reaction of tert-BuCl with AICI3 or GaCl3 in anhydrous liquid HCl as a solvent, or of £ert-BuBr with AlBr3 in HBr. At — 30 °C solutions of [C(CH3)3 + ] are stable. At room temperature very slow decomposition occurs over months. In the systems BCI3/HCI, InCl3/HCl and BBr3/HBr no formation of [C(CH3)3+] from the corresponding £erZ-butyl halide was observed. The tert-'Amy\ cation can be stabilized only in AlBr3/HBr. The iso-propyl cation is not stable in any of the systems investigated. The ability of the Lewis acids employed to form carbenium ions corresponds with their catalytic activity in Friedel-Crafts alkylations. 
  Reference    Z. Naturforsch. 34b, 548—552 (1979); eingegangen am 5. Januar 1979 
  Published    1979 
  Keywords    Alkylcarbenium Ions, ferZ-Butyl Cation, Aluminium Halides, Hydrogen Halides, NMR 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0548.pdf 
 Identifier    ZNB-1979-34b-0548 
 Volume    34 
82Author    Peter Brüggeller, Erwin MayerRequires cookie*
 Title    Das JerJ-Butyl-Kation in Lösungen von Aluminiumbromid in Mono-, Di-und Tribrommethan The terf-Butyl-Cation in Solutions of Aluminium Bromide in Mono-, Di-and Tribromomethane  
 Abstract    The tert-butyl cation is formed from ieri-BuBr in concentrated solutions of AlBr3 in CHaBr, CH2Br2 and CHBr3 and was characterized by X H NMR spectroscopy. Stabilization of the cation depends strongly on the AlBr3 concentration: in CH^Br saturated with AlBr3, C(CH3)3+ is formed in 80% yield; in dilute solutions of AlBr3 in CH3Br the usual de-composition occurs. In saturated solutions of AlBr3 in CH2Br2 and CHBr3 the C(CH3)3+ yield is 60 and 40%, resp. The concentration of the cation decreases in all three solvents by 20 to 30% within 10 days at room temp. In concentrated solutions of AlBr3 in CH^Br the formation of the methyl-Zer£-butylbromonium ion as a rapidly equilibrating species is suggested. The iH NMR chemical shift of C(CHs)3+ in the presence of AlBr3 (d = 5.19 in CHsBr, <5 = 5.23 in CH2Br2, 6 = 5.35 in CHBr3) indicates strong deshielding in comparison with shifts in SbF5 and SbF5/S02. 
  Reference    Z. Naturforsch. 34b, 891—895 (1979); eingegangen am 5. März 1979 
  Published    1979 
  Keywords    terf-Butyl Cation, Aluminium Bromide, NMR, Bromomethanes, Methyl Bromide 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0891.pdf 
 Identifier    ZNB-1979-34b-0891 
 Volume    34 
83Author    Werner Zeiß, Alfred SchmidpeterRequires cookie*
 Title    .3.4.2-Thiadiazaphospholin-2-thione l,3,4,2-Thiadiazaphospholine-2-thiones  
 Abstract    Perthiophosphonic anhydrides (1) and phos-phorus^) sulfide react with benzo-phenylhydra-zonoyl chloride (2) eliminating HCl and yielding the title compounds 3 and 4, which formally are cycloadducts of the monomeric units RPS2 and P2S5, respectively, and diphenyl nitrilimine. The corresponding cycloreversion is observed in their mass spectra. 
  Reference    Z. Naturforsch. 34b, 1042—1043 (1979); eingegangen am 26. März 1979 
  Published    1979 
  Keywords    Perthiophosphonic Anhydrides, Phosphorus(V) Sulfide, Cyclocondensation Reaction, NMR, Mass Spectra 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-1042_n.pdf 
 Identifier    ZNB-1979-34b-1042_n 
 Volume    34 
84Author    C. Cruz, P. J. Sebastião, J. Figueirinhas, A. C. Ribeiro, H. T. Nguyen, C. Destrade, F. NoackRequires cookie*
 Title    NMR Study of Molecular Dynamics in a D ho Columnar Mesophase  
 Abstract    In this paper we report the first molecular dynamics study combining fast field-cycling and conven-tional NMR techniques in a thermotropic liquid crystal of discotic molecules exhibiting an ordered columnar hexagonal mesophase. Using the association of these techniques we obtained proton T { data over a very large domain of Larmor frequencies (u/2n from 500 Hz to 85 MHz). The proton spin-lattice relaxation results were analysed considering the structure of the mesophase and the types of movements which are expected to influence significantly the relaxation rate, namely local molecu-lar rotational reorientations, inter-columnar self-diffusion and collective movements corresponding to bending and compression of the columns. We verified that these mechanisms dominate the relaxation respectively for high, medium and low Larmor frequencies. 
  Reference    Z. Naturforsch. 53a, 823—827 (1998); received July 16 1998 
  Published    1998 
  Keywords    NMR, Proton Relaxation, Molecular Dynamics, Columnar Hexagonal Mesophases (D ho ), Discotic Molecules 
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 TEI-XML for    default:Reihe_A/53/ZNA-1998-53a-0823.pdf 
 Identifier    ZNA-1998-53a-0823 
 Volume    53 
85Author    R. BauschRequires cookie*
 Title    Untersuchung der cis-trans-Isomerisierung in Bis(5.5-dimethyl-2-hexenyl)-zink mittels kernmagnetischer Sättigung A Nuclear Magnetic Saturation Study of the cis-trans Isomerization in Bis(5,5-dimethyl-2-hexenyl)-zinc  
 Abstract    Kinetic parameters of the cis-trans isomerization in bis(5,5-dimethyl-2-hexenyl)-zinc have been determined by means of nuclear magnetic saturation transfer. Novel methods for the acquisition and analysis of saturation data are reported. The results are consistent with a dynamic allylic system passing through the secondary metal alkenyl form as an intermediate in the equilibrium of cis-trans isomers. 
  Reference    (Z. Naturforsch. 31b, 765—768 [1976]; eingegangen am 21. Januar 1976) 
  Published    1976 
  Keywords    Saturation Transfer, Kinetics, NMR, Zinc-organic Compounds, Dynamic a-Allyls 
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 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-0765.pdf 
 Identifier    ZNB-1976-31b-0765 
 Volume    31 
86Author    Jochen Eilermann, HelmutA. LindnerRequires cookie*
 Title    Komplexchemie polyfunktioneller Liganden, 52 [1] Hydrido-und Deuterido-mangan(I)-carbonyl  
 Abstract    Komplexe des 1.1.1-Tris (diphenylphosphinomeihy 1) e thans Complex Chemistry of Polyfiinctional Ligands, 52 [1] Hydrido-and Deuterido-manganese(I)-carbonyl Complexes of 1,1,1 -Tris(diphenylphosphinomethyl)ethane 
  Reference    Z. Naturforsch. 34b, 799—804 (1979); eingegangen am 26. März 1979 
  Published    1979 
  Keywords    Deuterido-manganese(I)-carbonyl Complexes, 1, 1, 1 -Tris(diphenylphosphinomethyl)ethane, Vibrational Spectra, 31 P NMR, NMR 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0799.pdf 
 Identifier    ZNB-1979-34b-0799 
 Volume    34 
87Author    Friedrich-Wilhelm Grevels, Konrad Schneider, Carl Krüger, Richard GoddardRequires cookie*
 Title    Tricarbonyl(^ 4 -1.5-cümethylen-2.6-cümethylcyclooctan)eisen: photochemische Synthese und Struktur Tricarbonyl(^ 4 -l,5-dimethylene-2,6-dimethylcyclooctane)iron: Photochemical Synthesis and Structure  
 Abstract    Extended photolysis of pentacarbonyliron in neat 2,3-dimethylbutadiene results in dimerization of the diene and formation of tricarbonyl(?y 4 -l,5-dimethylene-2,6-dimethyl-cyclooctane)iron (1). The structure of complex 1 is characterized by a trigonal-bipyramidal geometry whereby the exocyclic double bonds of the diene ligand and one of the carbonyl groups lie exactly in the equatorial coordination plane. 
  Reference    Z. Naturforsch. 35b, 360—365 (1980); eingegangen am 5. November 1979 
  Published    1980 
  Keywords    Carbonyliron Olefin Complexes, Dimerization of Dimethylbutadiene, Photochemistry, NMR, X-ray 
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 TEI-XML for    default:Reihe_B/35/ZNB-1980-35b-0360.pdf 
 Identifier    ZNB-1980-35b-0360 
 Volume    35 
88Author    Sa-Ouk Kang, Helmut Sapper, Wolfgang LohmannRequires cookie*
 Title    The Oxidative Degradation of L-Ascorbic Acid via an a-Ketoaldehyde  
 Abstract    Dehydro-L-ascorbic acid, the oxidation product of L-ascorbic acid, is unstable in aqueous solution and decomposed by a hydrolytic disruption of its ring structure to 2,3-diketo-L-gulonic acid. It is shown by means of UV, 'H-, and 13C-NMR spectroscopy that after decarboxylation 3,4,5-trihydroxy-2-keto-L-valeraldehyde, an a-ketoaldehyde, is formed. This substance is oxidized further to L-erythroascorbic acid, coupled with a reduction of 2,3-diketo-L-gulonic acid to L-ascorbic acid. 
  Reference    Z. Naturforsch. 37c, 1064—1069 (1982); received August 24 1982 
  Published    1982 
  Keywords    L-Ascorbic Acid, Dehydro-L-Ascorbic Acid, a-Ketoaldehyde, L-Erythroascorbic Acid, NMR 
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 TEI-XML for    default:Reihe_C/37/ZNC-1982-37c-1064.pdf 
 Identifier    ZNC-1982-37c-1064 
 Volume    37 
89Author    T. Sc HRequires cookie*
 Title    Departm ent o f Chemistry, The U niversity, Leicester LEI 7RH, England and  
  Reference    (Z. Naturforsch. 30b, 969 [1975]; received June 19 1975) 
  Published    1975 
  Keywords    Acetylisocyanate, Chlorosulfonylisocyanate, NMR, Mass Spectra, 3-Chlorosulfonyl-6-methyl-2 H-l, 3, 5-oxadiazine-2, 4-(3 H)-dione 
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 TEI-XML for    default:Reihe_B/30/ZNB-1975-30b-0969_n.pdf 
 Identifier    ZNB-1975-30b-0969_n 
 Volume    30