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1Author    C. Wesdemiotis, H. Schwarz, C. C. Van De Sande, F. Van GaeverRequires cookie*
 Title    Transalkylierung und protonenkatalysierte C-C-Spaltung bei n-Butyl-und irc-Pentylbenzol in der Gasphase Transalkylation and Proton Catalyzed C-C-Cleavage of Gaseous n-Butyl and w-Pentyl Benzenes  
 Abstract    The investigation of several 13 carbon and deuterium labelled n-butyl and n-pentyl benzenes demonstrate that chemical ionization (reagent gas: methane) induces specific carbon-carbon bond cleavages of the alkyl group. The extent of competing reaction channels as for instance direct alkene elimination versus dealkylation/reprotonation is analyzed. Partial hydrogen exchange processes between reagent ions and substrate molecules are restricted to the phenyl ring. Intramolecular exchange reactions between the side chain and the aromatic ring which are typical for the open shell molecular ions of alkyl benzenes are not observed for analogous closed shell cations. Die von Munson und Field [1] in die Massen-spektrometrie eingeführte Methode der Chemischen Ionisation (CI) hat sich nach einer längeren Induk-tionsperiode innerhalb weniger Jahre als ein wir-kungsvolles Instrument bei der Lösung vielfältigster Problemstellungen in der Chemie erwiesen [2]. Bei diesem Verfahren werden durch Elektronenstoß-ionisation (EI) aus einem gegebenen Reaktandgas diverse Ionen erzeugt, die dann ihrerseits mit Sub-stratmolekülen M z.B. im Sinne von Säure/Base-Reaktionen reagieren. Verwendet man beispiels-weise Methan als Reaktandgas, so liegen als reaktive Species hauptsächlich [CHs] + , [C2Hö] + und [C3H5] + vor; diese ionisieren die Substratmoleküle M in schnellen Ion/Molekülreaktionen [3], wobei u.a. Ionen vom Typ [MX]+ entstehen (X = H, C2H5, C3H5). Die reaktiven Eigenschaften solcher "closed 
  Reference    Z. Naturforsch. 34b, 495—501 (1979); eingegangen am 8. Dezember 1978 
  Published    1979 
  Keywords    Chemical Ionization, Carbocations, Hydrocarbons 
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 TEI-XML for    default:Reihe_B/34/ZNB-1979-34b-0495.pdf 
 Identifier    ZNB-1979-34b-0495 
 Volume    34 
2Author    WaqarA. Hm, M. Uhammad Nazir3, FaqirM. Ohammad Chaudhary3, Ashfaq AhmRequires cookie*
 Title    Hydrocarbon Distribution in Epicuticular Waxes of Five Euphorbia Species  
 Abstract    The distribution pattern of hydrocarbons in the surface waxes of five species of Euphor­ biaceae, E.caducifolia, E.helioscopia, E.milii, E.royleana and E.tirucalli was studied. In addi­ tion to hom ologous series of n-alkanes, minor quantities of unsaturated and branched hy­ drocarbons were also detected. Some of the branched chain hydrocarbons could be explained as having originated from isoprene units and the substituents corresponding to diterpenes and triterpenes. 
  Reference    Z. Naturforsch. 51c, 291 (1996); received October 30 1995/January 2 1996 
  Published    1996 
  Keywords    Euphorbiaceae, Hydrocarbons, Epicuticular Wax 
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 TEI-XML for    default:Reihe_C/51/ZNC-1996-51c-0291.pdf 
 Identifier    ZNC-1996-51c-0291 
 Volume    51 
3Author    MatthewO. Ilori, Dan-Israel AmundRequires cookie*
 Title    Production of a Peptidoglycolipid Bioemulsifier by Pseudomonas aeruginosa Grown on Hydrocarbon  
 Abstract    A strain of Pseudomonas aeruginosa isolated from a polluted soil was found to produce an extracellular bioemulsifier when cultivated on hexadecane as sole carbon source. The emulsifier was precipitated with acetone and redissolved in sterile water. D odecane, crude oil and kerosene were found to be good substrates for emulsification by the bioemulsifier. Growth and bioemulsifier production reached the optimal levels on the fourth and fifth day, respectively. Emulsifying activity was observed over a pH range o f 3.5 to 10.0 with a maxi­ mum at pH 7.0. The activity o f the bioemulsifier was heat stable up to 70 °C while about 50 percent of its activity was retained at 100 °C. The com ponents of the bioem ulsifier were determined, it was found to contain carbohydrate, protein and lipid. The protein complex was precipitated with ammonium sulphate and fractionated on a Sephadex G-100. Gel elec­ trophoresis of the bioemulsifier showed a single band whose molecular weight was estimated as 14,322 Da. The bioemulsifier was classified as a peptidoglycolipid. Certain strains of P. aeruginosa produce peptidoglycolipid in place o f rhamnolipid. 
  Reference    Z. Naturforsch. 56c, 547 (2001); received February 6 /March 8 2001 
  Published    2001 
  Keywords    Pseudom onas, Hydrocarbon, Peptidoglycolipid 
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 TEI-XML for    default:Reihe_C/56/ZNC-2001-56c-0547.pdf 
 Identifier    ZNC-2001-56c-0547 
 Volume    56 
4Author    J. Heimbrecht, K. Levsen, H. SchwarzRequires cookie*
 Title    and their [M-CH3] + Fragments  
 Abstract    In contrast to the corresponding butyl ions the [M-CH3]+ ions from isomeric pentyl-benzenes do not isomerise completely to a mixture of interconverting structures prior to decomposition. 
  Reference    (Z. Naturforsch. 31b, 1299—1300 [1976]; received June 3 1976) 
  Published    1976 
  Keywords    Collisional Activation Spectra, Isomerisation, Mass Spectra, Hydrocarbons 
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 TEI-XML for    default:Reihe_B/31/ZNB-1976-31b-1299_n.pdf 
 Identifier    ZNB-1976-31b-1299_n 
 Volume    31 
5Author    Paul-Gerhard Giilz, Claudia EichRequires cookie*
 Title    Epicuticular Waxes from Leaves and Stems of Jojoba (Simmondsia chinensis [Link] Schneider)  
 Abstract    Epicuticular waxes were extracted with chloroform from air dried Jojoba leaves and stems. These cuticular waxes consisted o f hom ologues o f «-alkanes, branched alkanes, alkenes, wax esters, aldehydes, acetates, esters, free long chain fatty acids and alcohols. Both leaves and stems showed the same qualitative and quantitative com position with sim ilar distribution patterns. Very long chain and in most cases saturated com pounds are dom inating. The com position o f epicuticular waxes from Jojoba leaves and stem s is quite different from that o f Jojoba pericarp and seed coats and demonstrates an organ specific wax com position o f different aerial parts o f this plant. 
  Reference    Z. Naturforsch. 38c, 679 (1983); received June 7 1983 
  Published    1983 
  Keywords    Jojoba, Leaves, Sterns, Epicuticular Waxes, Hydrocarbons 
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 TEI-XML for    default:Reihe_C/38/ZNC-1983-38c-0679.pdf 
 Identifier    ZNC-1983-38c-0679 
 Volume    38 
6Author    Chrysostomos Wesdemiotis, Helmut Schwarz, Friedrich Borchers, Heinz Heimbach, Karsten LevsenRequires cookie*
 Title    Massenspektrometrische Untersuchungen zur Genese von [M—Me] [M-Et] [C7H7]+ und [C7H8]+ aus n-Butyl-und n-Pentylbenzol: Zeitabhängige Nachbargruppeneffekte, Isomerisierungen und kompetitive Wasserstoff-Umlagerungen Mass Spectrometric Investigations on the Formation of [M-Me]+, [M-Et]+, [C7H7] + and [C7H8] + - from w-Butyl and w-Pentyl Benzenes: Time Dependent Neighbouring Group Participation, Isomerization and Competitive Hydrogen Rearrangements  
 Abstract    The details of the elimination of CH3 1 and C2Hs -from the molecular ions of n-butyl and n-pentyl benzenes as well as the formation of C7H7+ and C7Hs + -have been established using a combination of different mass spectrometric techniques. Among these techniques are field ionization kinetics (FIK), collisional activation (CA), unimolecular decomposi-tion of metastable ions (MI), kinetic energy release determinations (Tkin)> appearance potential measurements (AP) as well as high resolution mass spectrometry. The appli-cation of these methods and the investigation of nine 13 carbon and eleven deuterium labelled n-butyl and n-pentyl benzenes clearly demonstrate that 1) the loss of methyl and ethyl from terminal positions of the alkyl chains are accompanied by an interaction with the phenyl ring and 2) the regioselectivity of these processes is time dependent. Contrary to previous conclusions it is shown that hydrogen transfer in the formation of C7H8 + -occurs via five-, six-and seven-membered transition states. The time dependence of the hydrogen exchange reaction preceding the alkene eliminations is discussed in detail. 
  Reference    Z. Naturforsch. 33b, 1150—1164 (1978); eingegangen am 1. März 1978 
  Published    1978 
  Keywords    Hydrocarbons, Hydrogen Rearrangement, Metastable Ions, Collisional Activation, Field Ionization Kinetics 
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 TEI-XML for    default:Reihe_B/33/ZNB-1978-33b-1150.pdf 
 Identifier    ZNB-1978-33b-1150 
 Volume    33 
7Author    Jiirgen Jacob, Gernot GrimmerRequires cookie*
 Title    Gefiederlipide der Ringeltaube Columbapalumbus Plumage Lipids from the Ring Dove ( Columba palum bus)  
 Abstract    Ring Only 6.7% of the whole plumage lipids of the ring dove originates from diester waxes of the uropygial gland secretion. The rest is distributed to hydrocarbons (3.3%), sterolesters and waxes (10.7%), free alcohols and sterols (5%), free fatty acids (55.6%), and unidentified material (18.7%). Among the hydrocarbons saturated odd-numbered, unbranched individuals predominate, but moreover 7-methylalkanes have been detected. The chain length of free and esterified alcohols cor­ responds to those of fatty acids where even-numbered compounds predominate. Main alcoholic component, however, is cholestanol. The origin of these lipids is discussed. 
  Reference    (Z. Naturforsch. 30c, 363 [1975]; eingegangen am 27. Dezember 1974) 
  Published    1975 
  Keywords    Dove Plumage, Feather Lipids, Hydrocarbons, Waxes, Alcohols, Free Fatty Acids 
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 TEI-XML for    default:Reihe_C/30/ZNC-1975-30c-0363.pdf 
 Identifier    ZNC-1975-30c-0363 
 Volume    30 
8Author    M. Uham, M. Ad, Nazir, W. Aqar, Ahm Ad, NaeemA. Khtar, Rabi, Shafiq Ahm, K. HanRequires cookie*
 Title    Epicuticular Leaf Wax of Euphorbia helioscopia L. (Euphorbiaceae)  
 Abstract    The epicuticular wax of Euphorbia helioscopia was fractionated into fatty acids, hydrocar­ bons, wax esters, aldehydes, methyl esters, triterpenol acetates, alcohols, sterols, and polar components. The com position o f the fractions was determined by GC, GC-MS, HPLC. Main com ponents within these lipid classes are hentriacontane, wax esters C ^ and C4g, octacosanal, hexacosanol and octacosanol, hexadecanoic acid, and ß-sitosterol. Lupeol and its acetate were also confirmed. 
  Reference    Z. Naturforsch. 48c, 5 (1993); received September 23 1992 
  Published    1993 
  Keywords    helioscopia, Epicuticular Wax Composition, Fatty Acids, Hydrocarbons, Wax Esters 
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 TEI-XML for    default:Reihe_C/48/ZNC-1993-48c-0005.pdf 
 Identifier    ZNC-1993-48c-0005 
 Volume    48