Phthalimide may also be made by using 500 g. of phthalic anhydride
and 500 g. of ammonium carbonate which has been previously ground
in a mortar. The subsequent procedure is the same as when aqueous
ammonia is used. Frequent shaking is necessary, and the sublimed
material must be occasionally pushed back into the reaction flask.
About two hours are required for completion.


2. Notes

Several smaller runs of 25 g. of phthalic anhydride gave
the same percentage yield.

Phthalimide may be recrystallized from water, but only about 4 g.
of phthalimide will dissolve in a liter of boiling water.
It may also be crystallized from alcohol, in which solvent it dissolves
to the extent of five parts in a hundred at boiling temperature.

On a large scale, it would be advisable to collect the small amount
of ammonia given off during the reaction.

If desired, the product obtained by pouring the reaction mass
into the crock may be treated with hot water to soften the cake,
broken up with a glass rod, transferred to a flask and boiled with water
for a few minutes. This treatment, however, is quite unnecessary;
for all practical purposes, the crude cake, as it is obtained,
may be ground up and used directly.