invention are incorporated into urethane foams by standard procedures this is typically done by premixing the flame retardant with the polyol the alternate methods of prereacting the flame retardant with the isocyanate or mixing several components simultaneously however are feasible the present invention will be more fully illustrated in the examples which follow a mixture of crotonaldehyde 400g and methanol 400ml was placed in a 2 liter 3 neck flask equipped with a thermometer reflux condenser addition funnel magnetic stirrer and ice water cooling bath to this mixture trimethyl phosphite 710g was added dropwise over a 3 hour period giving a slight exotherm the maximum pot temperature was 36 u00b0 c after standing 16 hours at room temperature the mixture was heated at reflux 80 u00b0 85 u00b0 c for 81 2 hours volatiles were then removed by vacuum stripping on a rotary evaporator water 210g was mixed with concentrated hcl 5ml and added to the residue from the vacuum stripping this was done in order to hydrolyze the intermediate acetal this reaction mixture was allowed to stand 16 hours at room temperature heated at 50 u00b0 60 u00b0 c for 2 hours and distilled distillation was carried out under gradually reduced pressure the major product fraction contained 573g and boiled at 98 u00b0 117 u00b0 c at 0 07 0 30mm the yield was 57 the infra red spectra showed a strong carbonyl absorption at 1717cm 1 and a strong phosphoryl absorption at 1240 1250cm 1 this preparation as well as ii iii amp iv all use the method described by r g harvey tetrahedron 22 2561 2573.