Chemistry Reference
In-Depth Information
Ester
Made from
Structure
3D model
Alcohol
Carboxylic acid
Ethyl ethanoate
CH
3
COOC
2
H
5
Ethanol
C
2
H
5
OH
Ethanoic acid
CH
3
COOH
H
O
HH
H
C
C
O
C
C
H
H
HH
Propyl methanoate
HCOOC
3
H
7
Propan 1-ol
C
3
H
7
OH
Methanoic acid
HCOOH
O
HH
H
H
C
O
C
C
C
H
HH
H
Methyl butanoate
C
3
H
7
COOCH
3
Methanol
CH
3
OH
Butanoic acid
C
3
H
7
COOH
H
HH
O
H
H
C
C
C
C
O
C
H
H
HH
H
Figure 15.10
The molecules of esters look like the 3D models in the photographs.
Figure 15.10 shows the actual arrangement of the
atoms in some of the members of this family.
Many esters occur naturally and are responsible
for the fl avours in fruits and the smells of fl owers.
They are used, therefore, in some food fl avourings
and in perfumes (Figure 15.11).
3
Which of the following organic chemicals are carboxylic
acids or alcohols?
Hexanoic acid, C
6
H
13
COOH
Butanol, C
4
H
9
OH
Octane, C
8
H
18
Nonane, C
9
H
20
Methanoic acid, HCOOH
Pentene, C
5
H
10
Hexanol, C
6
H
13
OH
State why you have chosen your answers.
Other carboxylic acids
Aspirin
Aspirin (Figure 15.12) is one of the most frequently
used painkillers in the world. It is also able to reduce
infl ammation and fever and a low dose taken on a daily
basis over the age of 50 may prevent heart attacks. It is
derived from another acid, salicylic acid, which can be
obtained from willow bark. Salicylic acid has the same
medicinal properties as aspirin and has been known
since 1829. Salicylic acid, however, caused stomach
bleeding. The conversion of salicylic acid to aspirin
reduced these problems, but aspirin still has some
adverse effects on the stomach if taken in excess.
Figure 15.11
Perfumes contain esters.
Fats and oils are naturally occurring esters which are
used as energy storage compounds by plants and
animals. They possess the same linkage as Terylene
but have different units (see p. 241).
Questions
1
Write the structural formula for propanoic acid.
2
Write word and balanced chemical equations for the
esterifi cation of propanoic acid with ethanol.
