One novel and ten known substituted 3′-and 4′-phthalanilic acids have been prepared. These have been cyclised to two novel and nine known substituted N-phenylphthalimides by heating with glacial acetic acid. Both phthalanilic acids and imides have been characterised in detail and spectroscopic data are given. The kinetics of cyclisation for phthalanilic acids has been examined in detail, and it has emerged that a complex ...