Question

What reaction results in the formation of an amide?

Answer 1

`RC(=O)X + 2H_2NR rarr R(C=O)N(H)R + HX*H_2NR`

Explanation:

As shown, this is the amine equivalent to the esterification reaction. An acid halide is treated with 2 equiv of amine, 1 equiv forms the `(O=)C-N` bond, the other equiv sops up the liberated `HX` as the ammonium salt. (If the amine were expensive, I could use just the 1 equiv. and use `Et_3N` as the base.)

Alternatively (and less likely) you may mean the formation of amido, `""^(-)NH_2` anions:

`2NH_3 rightleftharpoons NH_4^(+) + NH_2^-`.

This equilibrium operates in liquid ammonia, and is precisely equivalent to the acid/base equilibrium that water undergoes:

`2H_2O(l) rightleftharpoons H_3O^+ + HO^-`