Question

How does an acid-base reaction influence the solubility of each component in solution to allow for separation?

Answer 1

The idea behind an acid-base extraction is to utilize the acid-base properties of organic compounds and selectively isolate them from one another when they're present in a mixture. In organic chemistry, acids are known as carboxylic acids and contain the -COOH functional group. Bases contain at least one nitrogen atom and are commonly called amines. When the acid-base mixture is treated with aqueous sodium hydroxide (a base), it will react only with the carboxylic acid in the mixture, forming a water-soluble salt which can be separated later. Neutral organic compounds don't have properties of either acids or bases.

If the mixture is treated with aqueous hydrochloric acid, it will react with the amine in the mixture, again forming a water-soluble salt that can be separated later. So really, we are just leveraging each component's ability to react with either sodium hydroxide or hydrochloric acid to allow us to isolate them from one another.