One Step Synthesis of 1,4-Dialkyl-1,4-Diphospha 2,3,5,6-Tetra -Hydroxycyclohexanes from Primary Alkylphosphines and Glyoxal

Abstract

High yields of 1,4-dialkyl 1,4-diphospha 2,3,5,6 tetrahydroxycyclohexanes are produced when equal molar portions of glyoxal are added to primary alkylphosphines. The reactions take place at low temperatures and without the aid of an acid catalyst. The cyclic products are readily converted to the corresponding 1,4 diphosphoryl or dithiophosphoryl derivatives with the addition of a slight excess of H₂O₂ or sulphur. Of particular importance are the order and rates of addition of the two reagents. Reversal of the addition of the reagents results in an entirely different product. This synthesis offers an easy route to 1,4-diphosphacyclohexanes. In addition, the oxides of the lower homologs have utility as flame retardants for polymethymethacrylate and other plastics.