Interaction of alkylamines with different types of layered compounds
Abstract
Long chain alkylamines CnH2n+1NH2 can be successfully used as guest molecules to test an intracrystalline reactivity of layered materials. A large variety of host compounds consisting of neutral layers intercalate alkylamines. Generally the alkylamines between the layers aggregate to paraffin-type structures. If the successive layers are negatively charged and separated by an interlayer region containing exchangeable cations, alkylammonium ions can be bound by cation exchange. The alkylammonium ions between the solid surfaces aggregate in a diversity of structures. Besides paraffin-type structures of the chains in all-trans conformation (exemplified by KniAsO4, aggregates of chain containing gauche-conformations are commonly formed. Typical are gauche-block structures as in alkylammonium silver decamolybdate. The exchangeable cations in the interlayer region of many non-silicatic compounds are not quantitatively exchanged. The exchanged proceeds to such an extent that distinct types of alkyl chain arrays can be formed. In many cases, the required packing density of the chains is obtained by an additional uptake of alkylamine during exchange of the alkylammonium ions. Under very distinct conditions crystals of several alkylammonium derivatives disintegrate into individual layers or thin packets of a few of such layers, so that colloidal dispersions form.
References (37)
- G. Alberti et al.
J. Mol. Catal.
(1984) - G. Lagaly
Colloid Interface Sci.
(1979) - A. Grandin et al.
J. Solid State Chem.
(1985) - G. Lagaly et al.
- G. Alberti et al.
J. Colloid Interf. Sci.
(1985) - M.S. Whittingham et al.
Intercalation chemistry
- A. Weiss et al.
Z. Anorg. Allgem. Chem.
(1953) - J.P. Goupta et al.
J. Chem. Soc. Dalton Trans.
(1979) - R.M. Tindwa et al.
J. Chem. Soc. Faraday Trans. I
(1985) - E. Michel et al.
Z. Naturforsch.
(1965)
Z. Naturforsch.
Am. Mineral.
Z. Naturforsch.
Phil. Trans. Roy. Soc. (London) A
Z. Naturforsch.
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