Untitled - Kelly Walsh High School

Organic, Biochemistry, and Polymers 321
It is possible to reverse the formation of an ester by a catalyzed hydrolysis reaction.
In this reaction, the water reenters the molecule where it was removed. If
an acid is the catalyst, the original acid and alcohol will reform. If a base is the
catalyst, the alcohol will reform; however, the acid will react further to produce
its conjugate base. The base-catalyzed hydrolysis of an ester is saponification.
If a molecule has multiple functional groups, multiple reactions may occur. For
example, the reaction of molecules with two carboxylic acid groups might react
with molecules containing two alcohol groups in the following manner.
H O (CH 2 ) 6 O H O C
H N
H
After multiple condensation reactions, the molecules join to give:
(CH 2 ) 6 N
H
O
O (CH 2 ) 6 O C
H O C
N
H
H
H
O
O
(CH 2 ) 6 N
(CH 2 ) 4
(CH 2 ) 4
H
O
C
O
C
(CH 2 ) 4
O
C
O
H
O
H
(CH 2 ) 4
H O (CH 2) 6 O H O C
O
C
H N
O
C
H
O
O (CH 2) 6 O C
N
H
(CH 2) 6 N
H
(CH 2) 6 N
H
H O C
H
O
C
O
(CH 2) 4
The resultant molecule is a polymer held together by many ester groups. Such
a polymer is a polyester. The linkage through multiple condensation reactions
results in a condensation polymer.
If we replace the di-alcohol in the preceding reaction with a di-amine we get:
After multiple condensation reactions, the molecules join to give:
H
O
(CH 2 ) 4
(CH 2 ) 4
(CH 2 ) 4
Multiple amide groups link the resultant polymer. For this reason, this condensation
polymer is a polyamide; however, DuPont did not like this name, so we
now know this polymer to be an example of a nylon. If the units joined by the
O
C
O
C
O
C
O
C
O
H
O
H