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.
One-pot acetalizations of cyclohexanone. acetophenone and benzophenone were carried out using methanol over H-montmorillonite clay
(a mesoporous material). silica, alumina, and different zeolites such as HFAU-Y.HBeta, H-ZSM-5, and H-mordenite. In all the cases a single
product-the corresponding dimethylacetal-was obtained in high yields. Hemiacetal formation was not observed with any catalyst. A
comparison of catalytic activity indicated that montmorillonite K-10 is the most active catalyst for the reaction. As evidenced by the reaction
time studies, the catalyst decay is greater over the zeolite catalyst than over the clay.
Ambili, V K; Dr.Sugunan, S(Cochin University of Science and Technology, April , 2011)
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Abstract:
To meet the challenges related to the chemical industry,development of efficient catalysts is necessary.The mesoporous materials like SBA-15 are considered as good catalyst candidates of 21st century.SBA-15 mesoporous materials are catalytically inactive,but allow the dispersion of catalytically active phases into the framework.So these materials can be considered as an interesting alternative for preparing catalytically active metal nanoparticles in-situ into it.In the present work various transition metals are incorporated to improve the catalytic activity of SBA-15 material.The fundamental aspects of the preparation,characterization and the activity studies are briefly viewed in this thesis. Systematic investigation of the physico-chemical properties and catalytic activity studies of the prepared materials were carried out and presented in this Study.
Description:
Department of Applied Chemistry,Cochin University of Science and Technology
Bejoy, Thomas; Prathapan, Sreedharan; Sugunan, Sankaran(Elsevier, May , 2005)
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Abstract:
The synthesis of dimethyl acetals of carbonyl compounds such as cyclohexanone, acetophenone, and benzophenone has successfully been carried out by the reaction between ketones and methanol using different solid acid catalysts. The strong influence of the textural properties of the catalysts such as acid amount and adsorption properties (surface area and pore volume) determine the catalytic activity. The molecular size of the reactants and products determine the acetalization ability of a particular ketone. The hydrophobicity of the various rare earth exchanged Mg–Y zeolites, K-10 montmorillonite clay, and cerium exchanged montmorillonite (which shows maximum activity) is more determinant than the number of active sites present on the catalyst. The optimum number of acidic sites as well as dehydrating ability of Ce3+-montmorillonite and K-10 montmorillonite clays and various rare earth exchanged Mg–Y zeolites seem to work well in shifting the equilibrium to the product side.