Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Organic help

  1. Jan 31, 2005 #1
    can any body help me to answer this question?
    Comoplete hydrogenation of 1,3,5,7-cyclooctatetraene is exothermic by -101 kcal/mole. Hydrogenation of cyclooctene proceeds with delta H equal to -23kcal/mol. On the basis of these data, would you call cyclooctatetraene armotic? Justify your anser. Would you expect more than one distinct isomer of 1,2-dimethylcyclooctatetrane to exist? If so, explain our reasoning.
     
  2. jcsd
  3. Feb 1, 2005 #2

    chem_tr

    User Avatar
    Science Advisor
    Gold Member

    Hello, four C=C bonds give 101 kcal/mol when saturated, so one bond would give one fourth of it, equal to 25.25 kcal/mol. The small difference indicates that a tendency to aromatic may be present, but not enough.

    About your second question, I'd say that since cyclooctatetraene is a cyclic compound, it is not likely that trans-dimethyl product would be so stable, so only cis-isomer is expected to occur with a considerable magnitude. This is my reasoning, I did not look up anywhere, so I cannot guarantee my last answer.
     
  4. Feb 1, 2005 #3

    GCT

    User Avatar
    Science Advisor
    Homework Helper

    "Cyclooctatetraene fails both requirements, although it has a ring of sp2 hybridized atoms. This molecule is not planar ( a geometry that would have 135º bond angles ). Angle strain is relieved by adopting a tub-shaped conformation; consequently, the p-orbitals can only overlap as isolated pairs, not over the entire ring. Furthermore, cyclooctatetraene has 8 π-electrons, a number not consistent with the Hückel Rule"

    http://www.cem.msu.edu/~reusch/VirtualText/react3.htm
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Organic help
  1. Organic help (Replies: 5)

  2. Organic Chemistry help (Replies: 1)

Loading...