1. Identify the intermolecular forces which can operate between molecules of the following
pure compounds:
(a)
(b)
O
H
N
(c)
(d)
N
O
Draw and name as many isomers of formula C5H12 as you can.
2. Give names for the following structures:
(a)
(d)
(b)
(c)
(e)
3. Draw the structures that correspond to the following names:
a. 2,2,3,3-tetramethylpentane
b. 2,2,4-trimethylpentane
c. 2,5-dimethylhexane
d. 4-cyclobutyldecane
e. methylcyclobutane
f. cyclohexylcyclohexane
4. Draw the alkanes that would result from hydrogenation of the following compounds:
(a)
(b)
(c)
5. Draw cyclohexane in the chair and boat conformations. Include all hydrogens and label
them axial or equatorial. Be careful how you draw these bonds. Look at the pictures on
p. 109 and 110.
6. Draw cis- and trans-1,3-dichlorocyclohexane in the most stable chair conformations.
Draw them in the least stable chair conformations. In each case, label the chlorines as
axial and equatorial.
7. Draw the Newman and sawhorse projections for the lowest energy rotational isomers of
propane. Then draw them for the highest energy rotational isomer.
8. Draw both isomers of 1,2-dimethylcyclopropane (the cis and the trans isomers). Show
by means of Newman projections which is more stable.
Note that in the cis isomer, the methyls are eclipsed. Thus, this is the less stable isomer.
9. What is a “diaxial” interaction?
Check the glossary for Chapter 3
10. Cis-1,2-cyclopentanediol melts at about 32°C, while the trans-isomer melts at about
55°C. Why might this be so?
11. What simple physical test could you use to distinguish between ascorbic acid from
natural sources, which exists as a single enantiomer, and ascorbic acid produced in the
lab, which usually exists as the racemic mixture? Describe how you would carry out the
test.
12. Ascorbic acid has two stereogenic centres. Draw the structure and find the stereogenic
centres.
13. How many enantiomers can you draw for ascorbic acid? Draw them.
14. Sn1 substitution usually results in loss of optical activity. For the following reaction,
NaOH
H
Cl
H
OH
Starting with optically pure alkyl halide results in a product with [] = +1.5o. Why does the
product have any optical activity at all? If the specific rotation for this alcohol is +42.3o, what is
the optical purity of the product?
15. When silver nitrate is mixed with 2-bromobutane, a precipitate rapidly forms. Analysis
shows that this precipitate is silver bromide (AgBr). Show how this might have formed.
16. Tremorine causes a condition very similar to Parkinson’s disease (hence the name). How
would you prepare it from ethyne and any other materials that you need?
N
N
tremorine
17. I have accidentally mixed together some methanol and some octanol, and have asked for
your help. How could you separate these alcohols without using distillation?
18. Show how you could prepare
(a) 2-propanol from propane
(b) 1-propanol from propane