Preparation of secondary phosphinoxides

摘要

Secondary phosphine oxides R'R"P(=O)H (I) are prepd. by heating aminophosphines R'R"P.NR3R4 (II) with at least the stoichiometric amt. of water at -20 degrees to +100 degrees in the presence of a non-oxidising acid and with exclusion of air. R'-R4 are alkyl, cycloalkyl, aralkyl or aryl and (R3+R4) can form a C2-6-alkylene chain which may be interrupted by O or S atoms. Suitable acids are HCl, HBr, H2SO4 or H3PO4. Starting material II is prepd. by Grignarding dihalogen amino phosphines or by reaction of 1 mol. halogen phosphine with 2 mols. primary or secondary amine only one of which enters into II and the reaction mixture may be used without isolation of II. Di-Me-phosphineoxide is specifically claimed; it is a bacteriostatic agent. a corrosion inhibitor suitable for adding to lubricating oils and a flame resistor for plastics. I in general promote reactions that are catalysed by radical formers.