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1.
Acetalization of ketones on K-10 clay and rare earth exchanged HFAU-Y zeolites: A mild and facile procedure for the synthesis of dimethylacetals 总被引:3,自引:0,他引:3
Dimethylacetals of ketones; cyclohexanone, acetophenone, and benzophenone have been prepared by reacting ketones with methanol
under mild reaction conditions. Large pore zeolites (H-Y and its rare earth metal, Ce3+, La3+, and RE3+ modified forms), and mesoporous clay (K-10 montmorillonite and its cerium exchanged counterpart) with regular pore structure,
silica and silica-alumina have been used as catalysts. Clay catalysts are found to be much more active than zeolites, thanks
to slightly bigger pore size. The nature of the pores of the solid acid catalysts determine acetalization efficiency of a
particular catalyst. As evidenced by the reaction time studies, the catalyst decay is greater over the zeolites than over
the clays. Carrying out the reaction with ketones of different molecular sizes it is shown that K-10 clays and rare earth
exchanged H-Y zeolites are promising environmentally friendly catalysts for their use in the production fine chemicals. 相似文献
2.
Rare earth exchanged Na–Y zeolites, H-mordenite, K-10 montmorillonite clay and amorphous silica-alumina were effectively employed
for the continuous synthesis of nitriles. Dehydration of benzaldoxime and 4-methoxybenzaldoxime were carried out on these
catalysts at 473 K. Benzonitrile (dehydration product) was obtained in near quantitative yield with benzaldoxime whereas;
4-methoxybenzaldoxime produces both Beckmann rearrangement (4-methoxyphenylformamide) as well as dehydration products (4-methoxy
benzonitrile) in quantitative yields. The production of benzonitrile was near quantitative under heterogeneous reaction conditions.
The optimal protocol allows nitriles to be synthesized in good yields through the dehydration of aldoximes. Time on stream
(TOS) studies show decline in the activity of the catalysts due to neutralization of acid sites by the basic reactant and
product molecules and water formed during the dehydration of aldoximes. 相似文献