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Week # 6: Aldehydes and Ketones
Lectures - 15, 16, 17
Concepts:
Carbonyl group - pi bond
Boiling points, polarity, solubility
Chiral Molecules (definition), mirror images, Fischer projection,D amd L
glyceraldehyde, biological and drug examples.
Enantiomer, diasteroisomer
Hemiacetal and acetal as functional groups, ring hemiacetals
Reaction Summary: Write the word equations.
(first four are review)
Oxidation of primary alcohol:
Oxidation of secondary alcohol:
Oxidation of tertiary alcohol:
Oxidation of aldehyde:
Reduction or hydrogenation of aldehyde or ketone:
Synthesis of Hemiacetal:
Synthesis of Acetal:
Ques.1. Summarize the definitions of the three classes of alcohols including
an example of each, using 4 carbons.
Definition
Example
Primary:
Secondary:
Tertiary:
Ques. 2. a. Rank the compounds by boiling point (lowest to highest) and by
polarity. First write out the structures.
propanone, propanol, propane, methyl ethyl ether, and propanal
b. Are aldehyde and ketones able to hydrogen bond? What explains their
relative high polarity compared to alkanes or ethers?
Ques. 3. Which compound is more soluble in water? Explain your reason.
a. butanone or butane
b. 3-hexanone or propanone
c. 1-butanol or butanal
Ques. 4.a. Which of the following compounds contains at least one chiral
carbons. Circle that carbon.
OH
OH
H3C
C
C
H2
H2
C
H3C
H3C
CH3
C
H2
CH3
H
C
C
H2
CH
H2
C
O
H3C
CH3 H
C
C
H
CH3
O
b. Write the structures of D and L glyceraldehyde.
Ques. 5. Explain why both mirror images of a compound are not effective as
drugs? Use the L-dopa and D-dopa as examples. Draw out the structures
centered on the chiral carbons to show the mirror images.
HO
O
OH
C
HO
C
H2
NH 2
H
Review - Subtraction Reactions - Dehydration and Oxidation
Reaction Name
Word Equation
Example
8. Oxidation - pri. alcohol Pri. Alcohol + (O)
1-propanol + (O) 
 aldehyde + water
propanal
9. Oxidation - sec. alcohol Sec. Alcohol + (O)
 ketone + water
Aldehyde + (O)  Acid
10. Oxidation - aldehyde
2-propanol + (O) 
2-propanone
Propanal + (O) 
propanoic acid
Ques. 6. Write the structures and names of the reactants and products.
a) CH3CH2OH + (O)
----->
b) CH3CH2CH2OH + (O) ----->
OH
c)
+ (O) ----->
H3C
CH
C
H2
H2
C
d)
H3C
CH 3
H
C
+ (O) ----->
C
O
H2
Ques. 7: Write the names of the structures below.
Ques. 8: Write the names of the reactant structures:
CH3
+ (O)
CH
OH
H3C
C
H2
a.
b.
CH3
O
CH
H3C
C
H
+ (O)
CH3
CH
H3C
CH
CH3
+ (O)
OH
c.
Addition Reactions
6. Reduction (H2)
Aldehyde or ketone + hydrogen
 alcohol
Propanal + hydrogen
Propanone + hydrogen
Ques. 9. Write the structures and names of the reactants and products.
O
a.
CH 3
C
H2
H2
C
b.
H
C
C
H2
H3C
H2
C
c.
+ H2
C
H3C
H 3C
CH3 H
C
C
H
O
O
+ H2
+ H2
Ques. 10: Write the name of the reactants and the structures of the products.
a.
CH3
H3C
C
CH3
+ H2
O
b.
CH3
H3C
CH
H2C
O
CH
+ H2
CH3
H2C
H2C
CH
C
O
+ H2
C
H2
c.
d.
O
+ H2
Hemiacetal and acetal Functional Groups
In the simplest form, the hemiacetal is really the combination of two
functional groups.
A hemiacetal is an alcohol and ether ATTACHED TO THE
SAME CARBON.
An acetal is two ether groups ATTACHED TO THE SAME CARBON.
Hemiacetal Formation:
The aldehyde and alcohol approach each other as follows because of the
attraction of opposite charges on the polar groups. The reaction is written as an
equilibrium because the hemiacetal is unstable and reverts back to the original
aldehyde and alcohol.
1. The alcohol oxygen becomes bonded to the carbonyl carbon to form the
ether.
2. The carbon double bond oxygen electrons are used to bond the alcohol
hydrogen to the carbonyl oxygen
3. The alcohol oxygen-hydrogen bond is broken
The whole process can be remembered by saying: The aldehyde or ketone
oxygen becomes an alcohol. The alcohol oxygen becomes an ether.
Ques. 11: Identify the structures below as hemiacetals or acetals:
14. Hemiactal Synthesis
Alcohol + aldehyde or
ketone
 hemiacetal
Ethanal + methanol
15. Acetal Synthesis
(ether synthesis)
Alcohol + hemiactal
 acetal + water
Hemiacetal (above) +
methanol
Ques. 12:
a. If butanone reacts with one molecule of methanol, what is the structure
formed?
b. If butanone reacts with two molecules of methanol, what is the structure
formed?
Ques. 13. Write the structures and names of the reactants and products.
H2
C
a.
H3C
O
C
H
H3C
O
OH
C
H
H2
C
+
C
H 3C
HO
CH3
HO
d.
H3C
OH
+ 2 H3C
O
c.
H 3C
acetal
H2
C
b.
hemmiacetal
+
H2
C
C
O
CH3
CH3
+
CH3
hemmiacetal
H2
C
HO
CH3
acetal