D 4212 (OTTO) Diphenyliodonium hexafluorophosphate, ≥98% Cas 58109-40-3 - used as cationic photoinitiator and photoacid generator. It acts as a catalyst for the photochemical polymerization of various monomers. D 4212 (OTTO) Diphenyliodonium hexafluorophosphate, ≥98% Cas 58109-40-3 - used as arylating reagent as well as an oxidant in organic synthesis.