Compounds of formula I ##STR00001## Y is, for example,
C.sub.3-C.sub.12alkylene, butenylene, butynylene, or
C.sub.4-C.sub.12alkylene interrupted one or more times by non-consecutive
--O-- or --NR.sub.2--; R.sub.1 is a reactive group selected from OH, SH,
NR.sub.3R.sub.4, --(CO)--OH, --(CO)--NH.sub.2, SO.sub.3H,
--C(R.sub.5).dbd.CR.sub.6R.sub.7, oxiranyl, --O--(CO)--NH--R.sub.8--NCO
and --O--(CO)--R.sub.9--(CO)--X; R.sub.2 is hydrogen,
C.sub.1-C.sub.4alkyl or C.sub.2-C.sub.4hydroxyalkyl; R.sub.3 and R.sub.4
are each independently of the other hydrogen, C.sub.1-C.sub.4alkyl or
C.sub.2-C.sub.4hydroxyalkyl; R.sub.5, R.sub.6 and R.sub.7 are each
independently of the others hydrogen or methyl; R.sub.8 is, for example,
linear or branched C.sub.4-C.sub.12alkylene, or phenylene; R.sub.9 is,
for example, linear or branched C.sub.1-C.sub.16alkylene, --CH.dbd.CH--,
--CH.dbd.CH--CH.sub.2--, C.sub.6-cycloalkylene, phenylene or naphthylene;
and X, X.sub.1 and X.sub.2 are each independently of the others OH, Cl,
OCH.sub.3 or OC.sub.2H.sub.5; are suitable as photoinitiators that can be
incorporated in a formulation to be cured.