The Intercalation of Some Heterocyclic Amines into α-Titanium Hydrogenphosphate—Structural and Calorimetric Data
✍ Scribed by Liliane M. Nunes; Claudio Airoldi
- Publisher
- Elsevier Science
- Year
- 2000
- Tongue
- English
- Weight
- 172 KB
- Volume
- 154
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
The intercalation of the heterocyclic amines 2,6-lutidine, pyrazine, piperazine, and piperidine into -titanium hydrogenphosphate gave the maximum amounts intercalated in aqueous solutions of 0.45, 0.65, 2.77, and 6.52 mmol g ؊1 , respectively, through a batch method at 298 ؎ 1 K. The original interlamellar distance of 760 pm increased after intercalation of piperazine and piperidine molecules, while for 2,6-lutidine and pyrazine molecules no change was observed. These results suggested that the amines were bonded only on the surface of the host. All thermochemical data were obtained on a di4erential isothermic microcalorimetric instrument by means of a titration procedure. From thermal e4ect data, the variation in enthalpy for each system gave exothermic values of ؊ 6.56 ؎ 0.10, ؊ 1.00 ؎0.10, ؊ 10.10 ؎ 0.34, and ؊ 31.44 ؎ 0.71 kJ mol ؊1 for intercalations of the above sequence of heterocyclic amines. The infrared spectra are in agreement with acid+base reactions, involving the layered acid host O 3 P+OH of the inorganic matrix and the basic center atoms of the guest molecules.