invention are commercially available from a variety of sources including siltech corporation toronto ontario canada r 1 is r 5 u2014 och 2 ch 2 o a u2014 ch 2 ch ch 3 o b u2014 och 2 ch 2 o c u2014 a b and c are independently integers ranging from 0 to 20 compounds of this class are commercially available from a variety of manufacturers including siltech corporation of toronto ontario canada they conform to the following structure ch 3 u2014 ch 2 r u2014 och 2 ch 2 o a u2014 ch 2 ch ch 3 o b u2014 och 2 ch 2 o c u2014 x u2014 p o u2014 oh z a b and c are independently integers ranging from 0 to 20 products made with polyphosphoric acid are on average 90 monoester 10 diester this means on average the u201c x u201d value is 0 9 and the average z value is 2 1 to equal three substituents products made with p 2 o 5 are on average 50 monoester 50 diester this means on average the u201c x u201d value is 1 5 and the average z value is 1 5 to equal three substituents compounds of this class.