Synthesis of a series of polyurethanes containing phosphorus

As a contribution to the study of fire retardance in polyurethanes by phosphorus containing compounds, polyurethanes with phosphorus incorporated in the structure have been prepared and characterized. Mol ratios P atoms/urethane linkages up to 1.108 have been obtained. Preparations were carried out in three steps: (1) formation of a phosphorus containing polyol by reaction of butane diol (BD) with phenylphosphonic dichloride, (2) end capping of the polyol with methane-bis-(4-phenyl isocyanate) (MBPI) to form prepolymer and (3) reaction of prepolymer with MBPI and BD in various proportions.