SYNTHESIS, PROTONATION CONSTANTS OF A SERIES OF TRIAZAMACROCYCLE METHYLENEPHOSPHONIC ACIDS

Four six-basic phosphonic acids, 1,4,7-triazacyclononane-N,N',N ''-tri s(methylene-phosphonic acid) (NOTP), 1,4,7-triazacyclodecane-N,N',N '' -tris(methylenephosphonic acid) (DETP), 1,4,7-triazacycloundecane-N,N' ,N ''-tris(methylenephosphonic acid) (UDTP), and 1,4,7-triazacyclotrid ecane-N,N',N ''-tris(methylenephosphonic acid) (TDTP), were synthesize d by the modified Mannich reaction under the gentle conditions. The pr otonation properties of the four polyamino polymethylenephosphonic aci ds are investigated by means of potentiometric titration in aqueous me dium at 25 +/- 0.1 degrees C and an ionic strength I = 0.1 mol.L-1 KNO 3. The successive protonation constants of ligands are obtained separa tely. The results show that the size of the ligands' cavity play an im portant role in their protonations. (C) 1998 John Wiley & Sons, Inc.