Gabriel synthesis

[6][7] The alkylation of ammonia is often an unselective and inefficient route to amines.

In the Gabriel method, phthalimide anion is employed as a surrogate of H2N−.

In this method, the sodium or potassium salt of phthalimide is N-alkylated with a primary alkyl halide to give the corresponding N-alkylphthalimide.

This method produces a precipitate of phthalhydrazide (C6H4(CO)2N2H2) along with the primary amine: Gabriel synthesis generally fails with secondary alkyl halides.

For these reasons, other methods for liberating the amine from the phthalimide have been developed.