Alkane Problems
Extra Problems
26. Draw the following compounds.
a) 1-isopropylcyclohexane
b) tert-butyl chloride
c) sec-butyl bromide
d) ethyl chloride
e) tert-butylcyclopentane
f) 2-phenyl-5-isopropyldecane
g) 2-chloro-4-ethyl-3-methylheptane
h) cis-1-bromo-2-sec-butylcyclopentane
i) 6-ethyl-2,4,5-trimethyloctane
j) 4-ethyl-2,3,3,5-tetramethylhexane
k) 4-(1,1-dimethylethyl)nonane
l) bicyclo[3.2.1]octane
m) bicyclo[2.2.2]octane
n) 2,2,3,3-tetramethylheptane
o) 1,1-diethylcyclopentane
27. Name the following compounds:
28. On an exam, student named some compounds incorrectly. These names are incorrect, but they represent real structures. Draw the structures of the compounds, and name them correctly.
a) 2-propylpentane
b) 3-methylbutane
c) 3-isopropylpentane
d) 1,2-diethylbutane
e) cyclohexylethane
29. In the following groupings, identify all of the compounds that would have the name listed.
30. a) Draw a Newman projection of propane in a staggered conformation.
b) Draw the rotational energy diagram for propane. On your diagram, clearly indicate the position of staggered conformations and eclipsed conformations. Your diagram should include rotation through any two staggered and any two eclipsed conformations.
31. Draw the following compounds in their most stable chair conformation. Be sure that your drawing clearly shows which groups are axial (if any) and which are equatorial (if any).
32.
a) Draw trans-1-methyl-4-isopropylcyclohexane in planar form (no chair). Be sure to use wedge and dash lines to indicate stereochemistry.
b) Now, draw trans-1-methyl-4-isopropylcyclohexane in its lowest energy chair conformation.
c) Now, draw cis-1-methyl-4-isopropylcyclohexane in its lowest energy chair conformation.
d) Based on your answers to (b) and (c), is trans-1-methyl-4-isopropylcyclohexane higher in energy, lower in energy, or about the same energy as the cis isomer, or is there no way to tell? Explain your answer.
33. In the lowest energy conformation of the compound below (chair form), how many alkyl substituents are axial?
34.
a) Draw trans-1-bromo-3-ethylcyclohexane in planar form (no chair). Be sure to indicate the stereochemistry with wedge and dash lines.
b) Now, draw trans-1-bromo-3-ethylcyclohexane in its lowest energy conformation.
c) Now, draw cis-1-bromo-3-ethylcyclohexane in its lowest energy conformation.
d) Draw what cis-1-bromo-3-ethylcyclohexane would look like if it underwent a chair flip.
e) Based on your answers for the lowest energy confirmations in (b) and (c), is trans-1-bromo-3-ethylcyclohexane higher in energy than, lower in energy than, or about the same energy as the cis isomer, or is there no way to tell? Briefly, explain your answer.
35. a) Draw 1,2,3,4,5,6-hexachlorocyclohexane in its chair conformation with all chloro groups in the axial positions. b) Then, draw the chair flipped version with all chloro groups in the equatorial positions.
36. Name the following cyclohexanes.
37. Consider 2-methylpropane. Sighting along the C2-C3 bond, draw and label the Newman projections of both the most stable and least stable conformations.
38. What is the relative position of the substituents A and B to each other in the following conformation? (anti, eclipsed, or gauche)
39. Using Newman projections, draw all the staggered conformations of 1-chloropropane looking down carbon1-carbon2 bond. Label all anti and gauche forms.
40. Draw the Newman projections for the following compounds in their lowest energy conformations.
a) pentane looking down C1-C2 bond
b) butane looking down C3-C4 bond
c) 2,3-dimethylbutane looking down C2-C3 bond
d) 2,3-dimethylhexane looking down C2-C3
41.
a) Draw a Newman projection of the gauche conformation of 2-methyl pentane, looking down the C2-C3 bond.
b) Now, draw the Newman projection of the most stable conformation of 2-methyl pentane. This may or may not look like your answer for part (a).