Orgo Ch 3.13

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  1. The abundance of __ in nature is probably due to both their stability and the __ offered by their predictable conformations.
    • cyclohexane rings
    • selectivity
  2. The combustion data show that cyclohexane has __. 
    It must have bond angles near the __ (no __) ad also have no __ ( no __).
    • no ring strain
    • tetrahedral angle (no angle strain)
    • eclipsing of bonds (no torsional strain)
  3. A planar, regular hexagon would have bond angles of 120 rather than 109.5, implying some __. A planar ring would also have __ because the bonds on adjacent CH2 groups would be __. Therefore, the cyclohexane ring cannot be __.
    • angle strain
    • torsional strain
    • eclipsed
    • planar
  4. Cyclohexane achieves __ and __ by assuming the __. The most stable conformation is the __.
    • tetrahedral bond angles
    • staggered conformations
    • puckered conformation
    • chair conformation
  5. In the chair conformation, the angles between the carbon-carbon bonds are all __.
  6. The __ of cyclohexane also has bond angles of 109.5 and avoids __. It resembles the __ except hte footrest is folded upward. It sufferes from __ because there is __ of bonds.
    • boat conformation
    • angle strain
    • chair conformation
    • torsional strain
    • eclipsing
  7. This eclipsing forces two of the hydrogens on the ends of the "boat" to interfere with each other. They are called __ because they point upward from the ends of the boat like two.
    flagpole hydrogens
  8. A cyclohexane molecule in the boat conformation actually exists as a slightly skewed __: The __ move away from each other and the __ of the bonds is reduced.
    • twist boat conformation
    • flagpole hydrogens
    • eclipsing
  9. Even though the __ is lower in energy than the __, it is still about 23 kJ/ mol higher in energy than the __.
    • twist boat
    • symmetrical boat
    • chair conformation
  10. At any instant, most of the molecules in a __ sample are in __. The energy barrier between the boat and chair is sufficiently __, that the conformations interconvert many times each second.
    • chair conformations
    • low
  11. The __ from the chair to the boat takes place by the footrest of the chair flipping upward to form the boat.
  12. the highest-energy point in this process is the conformation where the footrest is __ with the sides of the molecule. This unstable arrangement is called the __.
    • planar with the sides of the molecule
    • half-chair conformation
  13. There are two types of __ in cyclohexane's __.
    • carbon-hydrogen
    • chair conformation
  14. Six of the bonds (one on each carbon atom) are directed __ and __, parallel to the __. These are called __.
    • up and down
    • axis of the ring
    • axial bonds
  15. The other six bonds point out from the ring, along the __ of the ring. These are called __.
    • equator
    • equatorial bonds
  16. Each carbon atom in cyclohexane is __.
    bonded to two carbon atoms, one directed upward and one downward
  17. The odd numberd carbon atoms have __. The even numbered carbon atoms have __.
    • axial bonds up and equatorial bonds down
    • equatorial bonds up and axial bonds down
Card Set:
Orgo Ch 3.13
2013-09-27 02:14:55
CHM 201

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