CARBON NUMBER-DEPENDENT INTERCALATION AND INTERLAYER AMIDATION PROPERTIES OF ALPHA,OMEGA-ALKANEDIAMINES FOR ALPHA-TITANIUM (2-CARBOXYETHYL)PHOSPHONATE PHOSPHATE

The uptake of alpha,omega-alkanediamines H2N(CH2)(n)NH2 (n = 2-10) by alpha-titanium (2-carboxyethyl)phosphonate phosphate, Ti(O3PCH2CH2CO2H )(1.91)(HPO4)(0.09), has been studied at 25 degrees C. Each diamine fo rms one or two intercalated phases in which the amine molecules are ar ranged as a monolayer with their axes tilted by 54 or 67 degrees relat ive to the inorganic layer. Diamines with n greater than or equal to 7 show a tendency to produce the high and low chain-tilt forms dependin g on the even and odd number of carbon atoms, respectively, but both f orms coexist for n = 6. For shorter chain diamines, on the other hand, only the low-tilt form occurs for n = 3, 4 and 5 and the high-tilt fo rm for n = 2. On heating at 150 degrees C or above the diammonium-exch anged solids were thermally condensed into the amide form with or with out any significant release of the amine guest. The amidation temperat ure shows a tendency to vary up or down depending on whether the carbo n number is even or odd.