Chemistry Reference
In-Depth Information
FIGURE 7.39
Preparation of esters.
This equation shows the overall forward reaction. However, the acid-catalyzed
process is actually an equilibrium. As
Figure 7.40
shows, this equilibrium can be
shifted by having different reagents in excess.
FIGURE 7.40
The reversibility of esterification.
To understand this, you need to study the mechanisms of esterification and
reverse hydrolysis in
Figure 7.41
. This clearly shows there are several equilibrium
steps in the overall process.
FIGURE 7.41
Mechanism of acid-catalyzed esterification.
The hydrolysis of an ester to give a carboxylic acid and an alcohol can also be
done under basic conditions. This alternative reaction is by a standard nucleo-
philic acyl substitution.
7.8.3 Amides
As shown in
Figure 7.38
, amides can be formed by substitution reactions of
the acyl derivatives above them in the reactivity chart. Chapter 2 showed how
amides are classified as 1°, 2°, and 3° amides depending on the substitution at
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