Adsorption of alkylamines by a crystalline silicic acid

Amines are strongly adsorbed by the crystalline silica H4Si20O42·4H2O and are intercalated into the interlayer spaces. The adsorption of butyl-, hexyl-, octyl-, and decylamine from alcoholic solutions (ethanol, butanol…decanol) is competitive as both types of molecules, amines and alcohols, are adsorbed in the interlamellar space. The adsorption isotherms are presented as composite isotherms showing the specific reduced surface excess of amine, n°(n)/m, as a function of the molar fraction of amine in the equilibrium solution. These isotherms increase to a plateau-like section (n°(n)/m≈1·4 mmol/g) when the interlamellar adsorption is restricted to formation of monolayers of flat-lying molecules (in water, ethanol and butanol). In the presence of longer chain alcohols, the isotherms increase stepwise to a second "plateau" (at n1°(n)/m = 2·2-2·7 mmol/g) which corresponds to paraffin-type bilayers of amine and alcohol molecules. The composition of the adsorption phase is estimated from the specific reduced surface excess of amine on the basis of the interlamellar structure derived from basal spacing measurements.

Über die Natur der Siliciumdioxidmodifikation Silica-X / On the Nature of the Silica Modification "silica-X"

Silica-X described in 1964 as a new SiO2 modification is the dehydrated form of the crystalline silicic acid H2Si8O17 · xH2O which is obtained by cation exchange from the potassium silicate K2Si8O17 · xH2O.

Notizen:Kernmagnetische Relaxationszeit-Messungen an OH-Protonen einer kristallinen Kieselsäure/ Nuclear Magnetic Relaxation Measurements on the OH-Protons of a Crystalline Silicic Acid

The transversal relaxation times of the OH-protons of a crystalline silicic acid were measured. Two relaxation processes, clearly separated from each other, are related to the OH-protons in the silicate layers and to the OH-protons of water molecules in the interlayer spaces. From the initial magnetizations information is obtained about the water content in the interlayer space which does well agree with results given in thermal decomposition curves.

Über eine neue kristalline Kieselsäure der Zusammensetzung H2Si14O29 · 5 H2O mit Schichtstruktur und Befähigung zur Bildung von Intercalationsverbindungen / A Crystalline Silicic Acid H2Si14O29 · 5 H2O with Layer Structure and Capability of Formation of Intercalation Compounds

A crystalline silicic acid H2Si14O29 · 5H2O has been prepared by topochemical reaction of sodium silicate Na2Si14O29·12H2O with acids. The compound has a layer structure with silicate sheets of about 11.2 Å thickness. The layer structure is clearly established by two dimensional reactions, mainly the formation of intercalation compounds with X-oxides (dimethylsulfoxide, pyridine-N-oxides etc.), acid amides, urea and its derivatives and bases such as hydrazine and pyridine. Typical exemples are 2 (CH3)2SO · H2Si14O29, 2C5H5NO · H2Si14O29, 2, 7 HCONHCH3 · H2Si14O29; 2, 3 HCON (CH3)2 · H2Si14O29; 1, 6 HCONHC2H5 · H2Si14O29; 1, 6 HCON (C2H5)2 · H2Si14O29.