INTERCALATION AND INTERLAYER AMIDATION PROPERTIES OF N-ALKYLMONAMINESFOR GAMMA-ZIRCONIUM (2-CARBOXYETHYL)PHOSPHONATE PHOSPHATE

The uptake of n-alkylmonoamines CnH2n+1NH2 (n = 2-10) by gamma-zirconi um (2-carboxyethyl)phosphonate phosphate, ZrPO4(H2PO4)(0.36)(HO3PCH2CH 2CO2H-2)0.64 . 2.3H(2)O derived from gamma-zirconium phosphate has bee n studied at 25 degrees C. The alkylamines with n greater than or equa l to 4 form an intercalated phase in which the amine molecules are arr anged as a bilayer with their axes perpendicular to the inorganic laye rs, whereas the shorter-chain amines cannot be stably held in the inte rlayer space. The amine uptake increases with increasing carbon number until it reaches a constant value of 0.32 mol per formula weight for the amines with greater than or equal to 6. The amine uptake and IR da ta indicate that the ammoniated guest molecules replace primarily the protons of the interlayer carboxyl groups. On heating at 220 degrees C , the ionically bonded CO2-NH3+ group in the ammonium-exchanged solids is thermally condensed into the amide CONH form without any significa nt release of the amine guest.