Intercalation of alkanols and alkylamines in insoluble acid salts of tetravalent metals having a layered structure of γ-type

Abstract

Several n-alkanols, n-alkylmonoamines and n-alkyldiamines have been intercalated in the layered structure of γ-Ti(HPO 4) 2 and γ-Zr(HPO 4) 2. Alkanol intercalates are unstable to washing with solvents and to air drying and the analysis of the change of the interlayer distance with the size of the guest molecules suggests that the alkanols are arranged within the interlayer space in a more complex disposition than a bilayer of well oriented molecules. Alkylamine and diamine intercalates are stable to washing with polar solvents and begin to decompose at temperatures higher than 200°C. The composition of these intercalates reveals that only 50 or 66% of the ▪ groups, present in the exchangers, interact with the amino groups of the guest molecules, owing to the closeness of the active sites present on the faces of the layers. It seems that alkylamines and diamines are intercalated as a bilayer or monolayer, respectively, of extended molecules inclined at 55° with respect to the sheets, but the presence of “kink” or “gauche” blocks in the structure of the films constituted of long chain alkylamines cannot be excluded. It is pointed out that the use of α and γ layered exchangers permits the formation of bilayers of alkanols or alkylamines having different packing densities; the intercalates of these exchangers seem thus good models to study the phase transitions occurring in the structures of the bilayers.