essentially linear polyethylenepolyamines are prepared by reacting monoethanolamine with ethylenediamine in the presence of an intercalatively catalytically active tetravalent zirconium polymeric reaction product of an organo phosphonic acid or an ester thereof with a compound of tetravalent zirconium reactive therewith , such as zirconium trimethylene diphosphonate prepared by reacting trimethylenediphosphonic acid wth zirconyl chloride .