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ALDEHYDES, KETONES AND
CARBOXYLIC ACIDS
ALDEHYDES AND KETONES
• Aldehydes and ketones both contain the carbonyl
group (C=O).
• In aldehydes, the carbonyl group is attached to the
end carbon.
Example
O
H
butanal
• In ketones, the carbonyl group is attached to a carbon
that is not on the end.
Example
O
butanone
Physical Properties
• Like the hydroxyl group, the carbonyl group is polar
but does not allow for hydrogen bonding.
• Compare the physical properties of aldehydes and
ketones to corrresponding alkanes and alcohols.
NAMING ALDEHYDES
1. Take the longest chain containing the carbonyl
group, remove the “e” and add “al” as the ending.
2. Any substituents are numbered using the lowest
sum.
Examples:
H
O
O
H
C
C
C H
H
methanal
formaldehyde
H
Cl
O
H
ethanal
acetaldehyde
2-chloro-4-ethyl-1-hexanal
NAMING KETONES
1. Take the longest chain containing the carbonyl
group, remove the “e” and add “one” as the
ending.
2. If necessary indicate the position of the carbonyl
using the lowest numerical coefficient.
3. Any substituents are numbered so the sum is the
lowest.
Examples
O
O
O
C
C
CH3
CH 3
CH 3
propanone
acetone
H 3C
C
O
2,3-butadione
3-Ethyl-2-pentanone
CARBOXYLIC ACIDS
• Contain the carboxyl functional group
O
C OH
• Since the carboxyl group is polar, carboxylic acids
contain dipole-dipole forces and are able to
hydrogen bond.
• How does the carboxyl group affect the physical
properties of these compounds?
• They are weak acids that will ionize slightly in
water.
• The H on the –OH is the acidic hydrogen and leaves
when the acid is ionized.
NAMING CARBOXYLIC ACIDS
1. Identify the longest chain containing the carboxyl
group, remove the “e” and add “oic” acid.
Examples
O
O
C
H
methanoic acid
HO
C
H 3C
OH
ethanoic acid
COMMON ORGANIC ACIDS
O
O
C
H
formic acid
methanoic acid
(ant sting)
HO
O
OH
propionic acid
propanoic acid
O
C
H 3C
OH
acetic acid
ethanoic acid
(vinegar
3-4 % solution)
OH
butyric acid
butanoic acid
(rancid butter)
HO
O
C
OH
O
C
HO
O
OH
oxalic acid
ethandioc acid
(poison in rhubarb
leaves)
OH
O
OH
tartaric acid
2,3-dihydroxybutandioic acid
(baking soda)
O
OH
O
HO
HO
OH
OH
HO
O
lactic acid
2-hydroxypropanoic acid
(causes muscle cramps due to O2 debt)
O
citric acid
(oranges, TCA cycle)
HOMEWORK
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Pg 48 #1-5
Pg 51 #1-3
Pg 52 # 4
Pg 60 # 1, 2