In this section we will look at the kinds of reactions that amides undergo. As is the case with other compounds that are formed by intermolecular dehydration, these compounds can be decomposed by hydrolysis. That is, the reaction can be reversed.
This equation (also shown in Example 10-a) shows a hydrolysis reaction in which a molecule of water splits the amide and forms the amine and the acid from which the amide was originally made.
The -H and the -OH from the water end up in the amine and the carboxylic acid respectively. Such hydrolysis reactions can be catalyzed by the addition of an acid or the addition of a base. We will look at some of the consequences of the reaction taking place in an acidic or basic solution in a moment.
But first let's look at the reaction shown here, and consider the consequences of creating a weak acid (propanoic acid) and a weak base (methylamine) in the same solution.
They will react with one another to form their conjugate ionic acids and bases. I should say partly react or react reversibly because they are a weak acid and a weak base. Not only will propanoic acid and methylamine be formed, but also some propanoate ion and methylammonium ion. When we write down the equation for a hydrolysis reaction, we generally ignore these complicating factors.
Hydrolysis in Acidic Solution
However, when we know that the reaction is taking place in an acidic solution, it makes sense to pay attention to such details. In acid solution (shown here and in Example 10-b) the products are the acid form of the carboxylic acid and the conjugate acid of the amine.
Hydrolysis in Basic Solution
In basic solution (shown here and in example 10c) the products of the reaction are the conjugate base of the carboxylic acid and the basic form of the amine.
You will observe the hydrolysis of an amide when you do Part II of the Experiment for this lesson.
E-mail instructor: Kerry Cotter
Clackamas Community College