N-Chlorophthalimide in anhydrous acetic acid serves as a useful oxidizing reagent for use in various direct titrimetric analyses. N-Chlorophthalimide can be synthesized by reacting phthalimide, t-butyl hypochlorite, water and t-butyl alcohol. It participates in the synthesis of 2-amino-3-benzoyl-α-(methylthio)phenylacetamide.