CHEM 122: Introduction to Organic Chemistry
Chapter 9: Aldehydes and Ketones.
1. Following are structural formulas for two steroid hormones.
Cortisone
Aldosterone
a) Name the functional groups in each.
b) Mark all stereocenters in each hormone and state how many stereoisomers are
possible for each.
2. Draw structural formulas for the four aldehydes with the molecular formula
C5H10O. Which of these aldehydes are chiral?
3. Draw structural formulas for these aldehydes.
a)
b)
c)
d)
e)
f)
Formaldehyde
Propanal
3,7-Dimethyloctanal
Decanal
4-hydroxybenzaldehyde
2,3-Dihydroxypropanal
4. Draw structural formulas for these ketones.
a)
b)
c)
d)
e)
f)
Ethyl isopropyl ketone
2-Chlorocyclohexanone
2,4-Dimethyl-3-pentanone
Diisopropyl ketone
Acetone
2,5-Dimethylcyclohexanone
5. Write the IUPAC names for these compounds.
CHO
CHO
O
CHOH
O
a)
OH
b)
CHOH
c)
CH 2 OH
d)
NH 2
6. Explain why each name is incorrect. Write the correct IUPAC name for the
intended compound.
a)
b)
c)
d)
2-Pentanal
Cyclopentanal
3-Ethyl-2-butanone
5-Aminobenzaldehyde
7. Acetone is completely soluble in water, but 4-heptanone is completely insoluble
in water. Explain.
8. Account for the fact that acetone has a higher boiling point (56oC) than ethyl
methyl ether (11oC) even though their molecular weights are almost the same.
9. Propanal (bp 49oC) and 1-propanol (bp 97o) have about the same molecular
weight, yet their boiling points differ by almost 50oC. Explain this fact.
10. Draw a structural formula for the principal organic product formed when each
compound is treated with Tollens’ reagent. If there is no reaction, say so.
a)
b)
c)
d)
Butanal
Benzaldehyde
Cyclohexanone
Cyclohexanol
11. Suppose that you take a bottle of benzaldehyde (a liquid, bp 179oC) from a shelf
and find a white solid in the bottom of the bottle. The solid turns litmus red; that
is, it is acidic. Yet aldehydes are neutral compounds. How can you explain these
observations?
12. Write a structural formula for the principal organic product formed by treating
each compound with NaBH4 followed by H2O.
O
O
a) CH3CCH2CH3
b) CH3(CH2)4CH
O
O
CH
CH 3
c)
OH
d)
13. Draw a structural formula for the product formed by treatment of butanal with
each set of reagents.
a)
b)
c)
d)
H2/metal catalyst
NaBH4, then H2O
Ag(NH3)2+ (Tollens’ reagent)
K2Cr2O7/H2SO4
14. Draw a structural formula for the product formed by treatment of acetophenone,
C6H5COCH3, with each set of reagents.
a)
b)
c)
d)
H2/metal catalyst
NaBH4, then H2O
Ag(NH3)2+ (Tollens’ reagent)
K2Cr2O7/H2SO4
15. Draw all enol forms of each aldehyde and ketone.
O
a) CH3CH2CH
O
CH 3
c)
O
b) CH3CCH2CH3
16. Which compounds are hemiacetals, which acetals, and which are neither?
OCH 3
CHOCH 3
a)
b)
O
d)
CH3CH2CHOCH3
O
CH2CH3
O
c)
OCH 2 CH 3
CH3OCH2OCH3
OH
O
e)
f)
17. Draw the hemiacetal and then acetal formed in each reaction. In each case,
assume an excess of the alcohol.
a) Propanal + methanol 
b) Cyclopentanone + methanol 
18. Draw the structures of the aldehydes or ketones and alcohols formed when these
acetals are treated with aqueous acid and hydrolyzed.
OCH 3
OCH 3
O
a)
b)
OCH 3
O
OCH 3
O
OCH 3
c)
OCH 3
d)
19. List the reagents and experimental conditions to convert cyclohexanone to each of
the following compounds.
20. Draw a structural formula for an aldehyde or a ketone that can be reduced to
produce each alcohol. If none exists, say so.
CH 3
CH2 OH
H3C
OH
a)
b)
c)
COH
CH 3
d)
HO
OH
21. Show how to bring about these conversions. In addition to the given starting
material, use any other organic or inorganic reagents as necessary.
22. Describe a simple chemical test by which you could distinguish between the
members of each pair of compounds.
a) Cyclohexanone and aniline
b) Cyclohexene and cyclohexanol
c) Benzaldehyde and cinnamaldehyde
23. 5-Hydroxyhexanal forms a six-membered cyclic hemiacetal, which predominates
at equilibrium in aqueous solution.
a) Draw a structural formula for this cyclic hemiacetal.
b) How many stereoisomers are possible for 5-hydroxyhexanal?
c) How many stereoisomers are possible for this cyclic hemiacetal?
24. The following molecule is an enediol; each carbon of the double bond carries an
–OH group. Draw structural formulas for the -hydroxyketone and the
-hydroxyaldehyde with which this enediol is in equilibrium.
-hydroxyaldehyde
HC
OH
C
OH
CH 3
An enediol
-hydroxyketone
25. Alcohols can be prepared by the acid-catalyzed hydration of alkenes and by the
reduction of aldehydes and ketones. Show how you might prepare each of the
following alcohols by 1) acid-catalyzed hydration of an alkene and 2) reduction of
an aldehyde or a ketone.
a)
b)
c)
d)
Ethanol
Cyclohexanol
2-Propanol
1-Phenylethanol
26. Glucose, C6H12O6, contains an aldehyde group but exists predominantly in the
form of the cyclic hemiacetal shown here. We will discuss this cyclic form of
glucose in Chapter 12.
CH 2OH
O OH
H
H
OH H
HO
H
H
OH
-D-Glucose
A cyclic hemiacetal is formed when the –OH group of one carbon bonds to the
carbonyl group of another carbon. Which carbon in glucose provides the –OH
group and which provides the CHO group?