T 2330 (OTTO) Triphenylphosphine oxide, 98% Cas 791-28-6 - used as a catalyst, Lewis base, ligand for metals and starting material for the preparation of other phosphorus compounds. T 2330 (OTTO) Triphenylphosphine oxide, 98% Cas 791-28-6 - used in epoxidations, Michael reactions and coupling reactions. It reacts with copper(II) halides and form coordination complexes of Copper(II).