<p>Arylazolactams, their preparation and use Cpds of the formula (I): where Ar is a (substd) phenyl or naphthyl gp and n=2 or 3. Pref. I is prepd by coupling lactam II (where m=3 or 4) with a diazonium salt of the corresp aromatic amine in the presence of a tertiary organic nitrogen base or in an acetate buffered soln at -20 to +25 degrees C. The title cpds may be used as photosensitisers in photopolymerisation of e.g. styrene acrylic acid etc.</p>
