Synergism between the Guest Compound and the Host Framework in Zeolite CsNaY after Impregnation with Cesium Hydroxide

Abstract

Even though compound 6 is extremely sensitive towards air it is thermally very stable and melts without decomposition at 237 "C. An irreversible rearrangement or decomposition reaction only occurs at above 267 "C and is indicated by a change in color from red to yellow. We will next investigate whether compound 6 can participate in typical reactions for 1,3-dienes, especially cycloadditions of the Diels-Alder type. Experimental SectionLithium (60 mg, 8.7 mmol) was added to a solution of 3 (700 mg, 0.81 mmol) in dimethoxyethane (30 mL) and the initially blue-green, later red, mixture was stirred for 2 h a t room temperature. After separation of insoluble materials, the remaining solution was cooled to -3O'C and treated with mesityl bromide (80 mg, 0.40 mmol). After the solution had been allowed to warm to room temperature, it was stirred for 16 h. The precipitated solid was filtered off and recrystallized from toluene to furnish 6 (280 mg, 53 % yield) as reddish brown crystals; m.p. 237-238°C; 'HNMR (Bruker AM300, [D,]benzene, 25'C): 6 = 0.16 (d, 3H, J = 6 . 6 H z ) , 0.24 (d, 3H, J = 6 . 5 H z ) , 0.34 (d, 3H, J = 6 . 5 H z ) , 0.45 (d, 3H, J=6.6Hz), 0.52 (d, 3H, J = 6 . 5 H z ) , 0.85 (d, 3H, J = 6 . 5 H z ) , 1.02 (d, 3H, J = 7 H z ) , 1.08 (d, 3H, J = 6 . 8 H z ) , 1.09 (d, 3H, J = 6 . 8 H z ) , 1.14 (d, 3H, J = 6 . 8 H z ) , 1.15 (d, 3H, J = 6 . 8 H z ) , 1.34 (d, 3H, J = 6 . 5 H z ) , 1.35 (d. 3H, J = 6 . 5 H z ) , 1.37 (d, 3H, J = 6 . 5 H z ) , 1.64 (d, 3H, J = 6 . 5 H z ) , 1.69 (d, 3H, J = 6.5 Hz), 1.78 (d, 3H, J = 6.6 Hz), 1.88 (d, 3H, J = 6.5 Hz), 2.55 (sept., 1 H, J=65Hz),2.64(sept., lH,J=6.5Hz),2.65(sept.,lH,J=6SHz),3.44(sept., 2H. J=6.5Hz),3,56(sept.,lH,J=6.8Hz),3.86(sept.,lH,J=6.5Hz),4.42 (sept., 1 H, J = 6."Si NMR (Bruker AMX300, [D,]benzene, 25°C): 6 = 52.3 (s), 89.5 (s); MS (CI, NH,): m/z (%): 1349 (4, MNH,'), 1332 (9, MH+); UV/Vis (THF): i.,,, (lge) = 392 (4.48). 518 (4.41) nm.

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.…”

“…and 16 C Ł H 3 I/u.c., respectively. The MAS central lines of both spectra consist of signals due to methoxy groups bound to guest compounds (50-52 ppm 7,20,21 ), methoxy groups bound to zeolitic framework oxygen atoms (55.3 ppm 7,16 -18,20,21 ) and dimethyl ether (61.0 ppm 16,20 ). On the sample loaded with 2 C Ł H 3 I/u.c., about 50% of the methoxy groups are bound to guest compounds (signals at 50-52 ppm).…”

“…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.…”

Mobility of Cations and Guest Compounds in Cesium-Exchanged and Impregnated Zeolites Y and X Investigated by High-Temperature MAS NMR Spectroscopy

“…18 The differences in the absolute chemical shift values are due to the different cation-exchange degrees of the zeolites CsNaY used. 17,18 In our previous investigations of dehydrated zeolites CsNaY impregnated with CsOH, 4,19 an additional broad hump with a center of gravity at about -30 ppm was found. This broad signal is due to cesium atoms contributing to alkali-metal-oxide guest compounds.…”

Cesium leaching from γ-irradiated CsA and CsX zeolites

“…3 and 4 include 133 Cs MAS NMR spectra for gammairradiated samples, CsX and CsA, heated at 673 and 973 or 1073 K. The assignment of peaks was made as in Norby et al [15] and Hunger et al [16]. As described by Norby et al, the peak intensities may represent the population of cesium in the various sites of the zeolite.…”