Give preparation of phthalimide from phthalic acid.
Correct Answer:
Phthalic acid can be converted to phthalimide through a reaction known as the Gabriel synthesis. Here are the steps to prepare phthalimide (Phthalamide) from phthalic acid:
- Dissolve phthalic acid in concentrated sulfuric acid to form the corresponding phthalic acid mono-sulfate.
- Heat the phthalic acid mono-sulfate with ammonium hydroxide to produce ammonium phthalate.
- React the ammonium phthalate with sodium hypochlorite to form chloramine phthalate.
- Treat chloramine phthalate with ammonia to produce phthalimide.
The overall reaction can be represented as follows:
Phthalic acid + NH3 + NaOCl → Phthalimide + NaCl + H2O Note that the Gabriel synthesis is a well-known and widely used method for the preparation of primary amines from carboxylic acids.