Orgo Ch 3.9-3.12

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  1. The higher alkanes resemble __ in their preference for __ and __ about the __ bonds. The lowest- energy conformation for any straight- chain alkane is the one with all the __ in their __.
    • butane
    • anti and gauche conformations 
    • C-C bonds
    • C-C bonds 
    • anti conformations
  2. These __ give the chain a __ shape. At rrom temp, the internal C-C bonds undergo rotation, and many molecuels contain __. 
    ___ make __ int he __ structure.
    • anti-conformations
    • zigzag
    • gauche conformations
    • Gauche conformations
    • kinks
    • zigzag
  3. Many organic compounds are __: __.
    cyclic: they contain rings of atoms
  4. __ are alkanes that contain rings of carbon atoms. Simple __ are named like __, with the prefix __ indiciating hte presence of a ring.
    • Cycloalkanes
    • cycloalkanes
    • acyclic (noncyclic) alkanes
  5. Simple cycloalkanes are ings of __. Each one has exactly __ as many hydrogens as carbons, giving the general formula __. 
    The general formula has __ fewer hydrogens than the __ formula for an acyclic alkane because a ring has no ends, and no hydrogens are needed to cap off the ends of the chain.
    • CH2 groups (methylene)
    • twice
    • CnH2n
    • two
    • 2n+2
  6. Most cycloalkanes resemble the __, open-chain alkanes in their physical properties and in their chemistry. They are __, relatively __ with __ and __ that depend on their MWs. The __ are held in a more compact __ shape, so their physical properties are similar to those of a compact, branched alkane.
    • acyclic (noncyclic)
    • nonpolar
    • inert compounds
    • BP and MP
    • cycloalkanes
    • cyclic
  7. Cycloalkanes are named much like the __. Substituted cycloalkanes use the __ for the base name, with the alkyl groups named as __. If there is just one substituent, __ is needed.
    • acyclic alkanes
    • cycloalkane
    • substituents
    • no numbering
  8. If there are two or more substituents on the ring, what?
    • the ring carbons are numbered to give the lowest possible numbers for the substituted carbons
    • The numbering begins with one of the substited ring carbons and continues in the direction that gives the lwest possible numbers to other substituents
  9. The substituents are named __.
    When the numebring could begin with either of two substituted ring carbons, begin with the one that __.
    • in alphabetical order
    • has more substituents, or else the one that is alphabetically first
  10. When the acyclic portion of the molecule contains more carbon atoms than the cyclic portion (or when it contains an important functional gorup), the cyclic portion is sometimes named as a __.
    cycloalkyl substituent
  11. __ undergo rotations around their c-c single bonds, so they are free to assume any of an infinite number of conformations. 
    Alkenes have __ that prevent rotation, giving rise to __ and __ with different orientations of the groups on the double bond.
    • open-chain (acyclic) alkanes
    • rigid double bonds
    • cis nad trans isomers
  12. True or False:
    Cycloalkanes are similar to alkenes in the aspect of cis and trans
  13. A cycloalkane has __. 
    If two substituents point toward the same face, they are __. IF they point toward opposite faces, they are __. These __ cannot interconvert without breaking and reforming bonds
    • two distinct faces
    • cis
    • trans
    • geometric isomers
  14. __ first attempted to explain the relative stabilities of cyclic molecules in the late 19th century, and was awarded the Nobel Prize.
    adolf Baeyer
  15. Baeyer's reasoning
    that the carbon atoms in acyclic alkanes have bond angles of 109.5
  16. If a cycloalkane requires bond angles other than __, the orbitals of its carbon-carbon bonds can't achieve optimum __, and the cycloalkane must have some __ (sometimes called __) associated with it.
    • 109.5
    • overlap
    • angle strain
    • Baeyer strain
  17. IN addition to this angle strain, the Newman projection in the figure shows that the bonds are __, resembling the __ conformation of butane.
    • eclipsed 
    • totally eclipsed
  18. Together, the __ and the __ add to give what we call the __ of the cyclic compound. The amount of __ depends primarily on the size of the ring.
    • angle strain
    • torsional strain
    • ring strain
    • ring strain
  19. In theory, we should measure the __ in the cyclic compound and subtract the amount of energy in a __.

    The difference should be the amount of __ due to __ in the cyclic compound. These measurements are commonly made using __.
    • total amount of energy
    • similar, strain-free reference compound
    • extra energy
    • ring strain
    • heats of combustion
  20. The __ is the amount of heat released when a compound is burned with an excess of oxygen in a sealed container called a __. If the compound has extra energy as a result of __, that extra energy is __ in the combustion.
    • heat of combustion
    • bomb calorimeter
    • ring strain
    • released
  21. The heat of combustion is usually measured how?
    by the temp rise in the water bath surrounding the bomb
  22. The molar heat of combustion of cyclohexane is __, simply because cyclohexane contains twice as many __ groups per mole.
    • twice that of cyclopropane
    • CH2 grops
  23. To compare the relative stabilities of cycloalkanes, we __.

    The result is the __
    divide the heat of combustion by the numebr of methylene groups

    energy per CH2 group
  24. What are the two factors that contribute to cyclopropane's large ring strain?
    angle strain

    torsional strain
  25. The first factor is the __ required to compress the bond angles from the tetrahedral angle of 109.5 to the __ degree angles of cyclopropane

    The bonding overlap of the carbon-carbon sp3 orbitals is weakened when __.

    The sp3 orbitals cannot point __, and they overlap at an angle to form __.
    • angle strain
    • 60
    • the bond angles differ so much from the tetrahedral angle
    • directly toward each other
    • weaker "bent bonds"
  26. __ is the second factor. The __ membered ring is __, and all the bonds are __. A __ of one of the carbon-carbon bonds shows that the conformation resemble sthe totally __ of __.
    The __ in cyclopropane is not as great as its __, but it helps to account for the large total __.
    • torsional strain
    • three
    • planar
    • eclipsed
    • Newman projection
    • eclipsed conformation
    • butane
    • torsional strain
    • angle strain
    • total ring strain
  27. True or False:
    Cyclopropane is generally less reqctive than other alkanes.
    • False 
    • more
  28. The __ in cyclobutane is almost as great as that in cyclopropane, but is distributed over four carbon atoms. 
    If cyclobutate were perfectly __ and ___, it would have 90 degree bond angles.
    • total ring strain
    • planar
    • squar
  29. A __ requires eclipsing of all hte bonds, as in cyclopropane. To reduce this __, cyclobutatne actually assumes a slightly folded form, with bond angles of __. These smaller bond angles require slightly more __ than ninety degree angles, but the relief of some of the __ appears to compensate for a small increase in __.
    • planar geomerty
    • torsional strain
    • 88 degrees
    • angle strain
    • torsional strain
    • angle strain
  30. If cyclopentane had the shape of a planar, regular pentagon, its bond angles would be 108, close to the tetrahedral angle of 109.5. A planar structure would require all the bonds to be __, hwoever.
  31. Cyclopentane actually assumes a slightly puckered __ conformation that reduces the __ and lowers the __. This __ is not __, but undulates by the thermal up-and-down-motion of the __. The flap of the envelope seems to move around the ring as the molecule undulates.
    • envelope
    • eclipsing
    • torsional strain
    • puckered shape
    • fixed
    • five methylene groups
Card Set:
Orgo Ch 3.9-3.12
2013-09-27 01:55:38
CHM 201

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