D 2325a (OTTO) Diphenyl diselenide, 98% Cas 1666-13-3 - used in the methoxyselenenylation of alkenes, dihydroxylation of double bonds, hydrothiolation of terminal alkynes. D 2325a (OTTO) Diphenyl diselenide, 98% Cas 1666-13-3 - used in the synthesis of the unsymmetrical diorganyl selenides, 1-(phenylselenomethyl)vinyl selenides, allylic phenyl selenides.