Organic Phosphorus Compounds 52. Preparation and properties of β-hydroxyalkyl-phosphonium salts and tertiary phosphine oxides

The new, tris- (2- hydroxyalkyl) - (hydroxymethyl) - phosphonium salts: [(RCHOHCH₂)₃ PCH₂OH]Cl (I, R = ClCH₂; III, R = CH₃) are formed in high yield by reaction of tetrakis-(hydroxymethyl)-phosphonium chloride (Tetrakis) with epoxides under basic conditions. Under the same conditions, styrene oxide yields only the disubstituted product, [(PhCHOHCH₂)₂ (CH₂OH)₂P]Cl. Optimal pH values for the reactions are 8 to 9; at lower pH the conversion is too slow; at a higher pH, oxidative decomposition of the salts occurs. Conversion of the salts to tertiary phosphine oxides (RCHOHCH₂)₃P ? O (R ? ClCH₂; CH₃) with loss of the hydroxymethyl group is best carried out with chlorine at pH 5 to 7. The yields are usually 60 to 90%.