Amines and Amides
Classification
For both amines and amides, classification based on number of carbon atoms attached to nitrogen. A single carbon atom (ex. CH3CH2NH2) attached to N makes compound primary (1°). Two carbons makes it secondary (2°), and three carbon atoms attached make the amine/amide tertiary (3°). While neutral amines cannot be attached to four carbons, quaternary (4°) ammonium ions having the general formula NR4+1 can be formed.
Basicity
| RNH2 | + | H2O | ¾® | RNH3+1 | + | OH-1 | pKb ~ 4-5 | |
| base | acid | acid | base | |||||
| RNH3+1 | + | H2O | ¾® | RNH2 | + | H3O+1 | pKa ~ 9-10 | |
| acid | base | base | acid |
Amides much less basic than amines due to resonance stabilization.
Reactions
Amines can act as nucleophiles in simple substitution reactions. Amides can be synthesized by normal routes for carboxylic acid derivatives. However, note that carboxylic acids themselves tend to react with amines in an acid/base reaction under normal conditions (high temperatures usually required to synthesize amide via this route).