A process for the preparation of benzophenonimine (BPI) of the general formula I where R1 and R2 are C1- to C4-alkoxy, C1- to C2-alkylamine and C2- to C4-dialkylamine and m and n are integers from 0 to 5 and R1 and R2, independently of one another, may be identical or different, by reacting benzophenone (BP) of the general formula II where R1, R2, m and n have the abovementioned meanings, in ammonia and in the presence of titanium dioxide, the titanium dioxide being present substantially in the anatase modification.