Reactive flame retardants for flexible polyurethane foams

A flame-retarded flexible polyurethane foam comprising the reaction product of a polyol, an isocyanate and a flame retardant-effective amount of a mono-hydroxyl-functional dialkyl phosphinate compound of the formula (I-A):

• wherein:
• R1 and R2 are selected from a linear or branched alkyl group containing from 1 to 4 carbon atoms;
• and,
• X is either ------(Z)k—R3 or
• and when X is ------(Z)k—R3, Z is —(Y—O)n—, wherein Y is a linear or branched alkylene group containing from 2 to 8 carbon atoms and n represents an integer from 1 to 20;
• k may be 0 or 1;
• R3 is selected from hydrogen, a mono-hydroxy-terminated linear or branched alkylene group containing from 2 to about 8 carbon atoms;
• and,
• provided that when k is zero, R3 is the mono-hydroxy-terminated linear or branched alkylene group and when k is 1, R3 is hydrogen, and
• when X is
• R4 and R5 are each independently selected from H, a linear or branched alkyl group containing from 1 to 8 carbon atoms, a linear or branched alkenyl group containing from 2 to 8 carbon atoms, a halo-substituted alkyl group containing from 1 to 8 carbon atoms, an alkoxy group containing from 1 to 8 carbon atoms, an aryl group containing from 6 to 12 carbon atoms and an alkylaryl group containing from 7 to 16 carbon atoms, or R4 and R5 are bonded to each other to form a cycloalkyl group containing from 5 to about 8 carbon atoms.