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  • 13C CP/MAS NMR  (2)
  • Isobutyl carbenium ion  (1)
  • 1
    Electronic Resource
    Electronic Resource
    13C solid state NMR evidence for the existence of isobutyl carbenium ion in the reaction of isobutyl alcohol dehydration in H-ZSM-5 zeolite (1993)
    Springer
    Catalysis letters 19 (1993), S. 153-158 
    Details
    ISSN: 1572-879X
    Keywords: Isobutyl carbenium ion ; carbon scrambling ; H-ZSM-5 zeolite ; 2DJ-resolved13C solid state NMR ; dehydration of isobutyl alcohol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Using two-dimensionalJ-resolved and CP/MAS13C NMR, the pathway for the transfer of the13C label from the CH2 group of isobutyl alcohol into the hydrocarbon skeleton of butene oligomers has been elucidated in the course of isobutyl alcohol dehydration inside H-ZSM-5 zeolite. First, the label is transferred selectively into the CH2 group of the isobutyl silyl ether reaction intermediate (IBSE), and then into the CH and CH3 groups of the isobutyl fragment (-CH2CH(CH3)2) of IBSE and/or butene oligomers. Finally, it is scrambled over the carbon skeleton of the oligomers. The obtained data suggest that isobutyl carbenium ion is formed as a reaction intermediate or transition state during the transformation of isobutyl silyl ether into butene oligomers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00771750
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  • 2
    Electronic Resource
    Electronic Resource
    Carbenium ion properties of octene-1 adsorbed on zeolite H-ZSM-5 (1994)
    Springer
    Catalysis letters 24 (1994), S. 271-284 
    Details
    ISSN: 1572-879X
    Keywords: Octene-1 ; H-ZSM-5 zeolite ; 13C carbon scrambling ; carbenium ion ; 13C CP/MAS NMR ; 2H NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract It is shown that octene-1 adsorbed on zeolite H-ZSM-5 at ambient temperature exhibits carbenium ion properties. Namely: (1) According to2H NMR, the proton of the acidic ≡Al-OH-Si≡ group of the zeolite is transferred into the CH2= group of the octene-1 molecule. (2) According to13C NMR the13C label inserted into the terminal CH2= group of the octene-1 molecule is scrambled over its hydrocarbon skeleton. Thermodynamic and kinetic parameters for carbon scrambling are measured within the temperature range 290–343 K. The zeolite framework is shown to favour the formation of the linear rather than branched carbeniumion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00811800
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  • 3
    Electronic Resource
    Electronic Resource
    13C CP/MAS NMR study of isobutyl alcohol dehydration on H-ZSM-5 zeolite. Evidence for the formation of stable isobutyl silyl ether intermediate (1992)
    Springer
    Catalysis letters 13 (1992), S. 395-405 
    Details
    ISSN: 1572-879X
    Keywords: Isobutyl alcohol ; dehydration ; H-ZSM-5 zeolite ; isobutyl silyl ether ; di-isobutyl ether ; carbenium ion ; 13C CP/MAS NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Dehydration of isobutyl alcohol selectively labelled with a13C nucleus in the CH2 group (i-BuOH[1−13C]) has been studied on H-ZSM-5 zeolite within the temperature range 296–448 K using13C CP/MAS NMR. The formation of the isobutyl silyl ether intermediate (IBSE) has been detected. It is stable below 398 K. Within the temperature range 398–423 K IBSE decomposes gradually to produce first a butene dimer, probably 2,5-dimethyl-l-hexene and then other butene dimers and oligomers. AtT 〉 423 K scrambling of the selectively labelled carbon of the initial dimeric product over various positions in the carbon skeleton of the final dimers (oligomers) is observed. This is explained in terms of the formation of carbenium ion as the reaction intermediate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00765043
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