Mechanistic studies of the side-chain alkylation of toluene with methanol on basic zeolites Y by multi-nuclear NMR spectroscopy1Dedicated to Professor Herman van Bekkum on the occasion of his 65th birthday.1

Characterization of basic guest compounds on solid catalysts by13C CP/MAS NMR spectroscopy of surface methoxy groups

“…We applied this method to investigate cesium-exchanged zeolites X and Y impregnated with cesium hydroxide. 7,20,21 In those studies, 7,20,21 the 13 C NMR chemical shifts of surface methoxy groups bound to framework oxygen atoms of the zeolitic host were found to be 54-56 ppm, in good agreement with the values reported by Bosacek.…”

“…The chemical shift anisotropy of  D 32 š 6 ppm obtained by this quantitative evalution is significantly higher than that of methoxy groups bound to guest compounds on impregnated silica gel. This fact and the slight resonance shift of the 13 C CP/MAS NMR signals due to methoxy groups bound to cesium oxidic compounds on silica gel (48.7 ppm), zeolite USY (49.4 ppm) and zeolite CsNaY-70 (50.0 ppm 20 ) are a hint at the influence of the support on the 13 C chemical shift tensor of surface methoxy groups.…”

“…7,20,21 In the present work, different guest compounds on silica gel, dealuminated zeolite USY and cesium-exchanged zeolite Y were studied by NMR spectroscopy. The principal aim was to study the influence of the supports and host materials on the 13 C chemical shift tensor of methoxy groups bound to these guest compounds.…”

Terminal and bridging methoxyls on zeolites detected by13C magic angle spinning NMR spectroscopy

“…In the case of the superloaded sample, oxygen atoms of cesium oxide or hydroxide which are present as guest substances in the zeolitic structure participate in this reaction as very basic sites. 27,28 On the other hand, both broad signals dominating in both spectra [ Fig. 5(A) and (B)] probably belong to chemisorbed methylium ions on the mentioned guest solid phase, thus forming terminating-type alkoxyls.…”

A green synthesis of α,β-unsaturated carbonyl compounds from glyceraldehyde acetonide

“…This decrease is due to the distortion of the crystal lattice caused by the introduction of the large cesium cation in the zeolite lattice. [26][27][28] Figure 2 shows the infrared spectra of NaX zeolite and of its cesium exchanged (CsX) and cesium impreganted (CsX/CS) forms; no significant changes were observed in the range 1300-450 cm -1 indicating that the ion exchange step and the impregnation of cesium species did not affect crystallinity. Similar results were observed for CsY and CsY/CS zeolites.…”