On the reaction of catenapoly(diphenoxy‐λ⁵‐phosphazene) with sulfur trioxide

The reaction of catenapoly(diphenoxy‐λ 5 ‐phosphazene) ( 1 ) with SO 3 in 1,2‐dichloroethane at 15°C, applying a mole ratio m = [SO 3 ]/[‐–P(OC 6 H 5 ) 2 N—] ≤ 1,0 and subsequent quenching with water, leads to catenapoly(diphenoxy‐λ 5 ‐phosphazene‐ co ‐diphenoxy‐λ 5 ‐phosphazenium hydrogen sulfate) ( 2 ) containing up to 57% protonated nitrogen. At m > 1,0 C ‐sulfonation occurs, resulting in the formation of water‐soluble catenapoly[diphenoxy‐λ 5 ‐phosphazene‐ co ‐diphenoxy‐λ 5 ‐phosphazenium hydrogen sulfate‐ co ‐bis(sulfophenoxy)‐λ 5 ‐phosphazenium hydrogen sulfate] ( 3 ). The latter can be converted into catenapoly[diphenoxy‐λ 5 ‐phosphazene‐ co ‐bis(sulfophenoxy)‐λ 5 ‐phosphazene] ( 4b ) by treatment with alkali and subsequent percolating through a cation exchange resin. Analytical results show that C ‐sulfonation is preceded by the formation of a polymer‐SO 3 donor‐acceptor complex.