Multi-nuclear solid-state NMR spectroscopy

The nitration of toluene with nitric acid and acetic anhydride with zeolite catalysts was studied by means of multi-nuclear solid-state NMR spectroscopy in order to explain the enhanced / ara-selectivity observed with zeolite beta. The reversible transformation of framework aluminum from a tetrahedral into an octahedral environment was revealed by A1 NMR upon interaction of the zeolite with the different components of the nitrating system. The flexibility of the lattice seems to play an important role in the regio-selectivity of nitration catalyzed by zeolites. 

The hydration properties of 2,3-O-hydroxypropylcellulose and 2,3-0-hydroxyethylcellulose were analyzed by multi-nuclear solid-state NMR spectroscopy. CPMAS and SPMAS in combination with NMR were carried out. Differences in mobile and immobile region within the polymers were determined. 

FIGURE 2.79 Concentration of bridging OH groups a function of the treatment temperature of silicoaluminophosphates H-SAPO-11, H-SAPO-18, H-SAPO-31, and H-SAPO-34 obtained by H MAS NMR spectroscopy. (Adapted from Micropor. Mesopor. Mater., 56, Buchholz, A., Wang, W., Xu, M., Arnold, A., and Hunger, M., Thermal stability and dehydroxylation of Brpnsted acid sites in silicoaluminophosphates H-SAPO-11, H-SAPO-18, H-SAPO-31, and H-SAPO-34 investigated by multi-nuclear solid-state NMR spectroscopy, 267-278, 2002, Copyright 2002, with permission from Elsevier.)... 

Local environments of main constituent elements (Si, Al, O, Mg, and Ca) in slow-cooled (crystalline) and rapid-quenched (amorphous) blast furnace slags have been investigated using multi-nuclear solid-state NMR spectroscopy. Natural abundance solid-state Mg NMR measurements were made of the disodium salt of magnesium ethylenediaminete-traacetate tetrahydrate. Both MAS and static experiments were employed to determine amongst other parameters, the Cq and the riq of the EFG tensor associated with Mg in this compound. ... 

Hunger, M. Brpnsted acid sites in zeolites eharacterized by multi-nuclear solid-state NMR spectroscopy. Catal Rev. Sci. Eng. 1997,39, 345-393. 

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