“…Selection of a suitable oxidizing agent can be troublesome, as readily oxidizable alkyl groups on the phosphorus atom and on the side chains of aromatic substituents may be involved in the reaction. The references to oxidation of phosphines with alkyl or aryl peroxides (29,40,51,55), hydrogen peroxide (44, 59, 71, 95,97,101), nitrogen tetroxide (1), nitric acid (91, 100), and amine oxides (57) denote work done in this area since 1950. It should be mentioned also that phosphines are frequently converted to the oxides upon standing in air or in the presence of oxygen (5,69).…”