Abstract
Catalytic behavior of isomorphously substituted B-, Al-, Ga-, and Fe-containing extra-large pore UTL zeolites was investigated in Knoevenagel condensation involving aldehydes, Pechmann condensation of 1-naphthol with ethylacetoacetate, and Prins reaction of β-pinene with formaldehyde and compared with large-pore aluminosilicate zeolite beta and representative Metal-Organic-Frameworks Cu3(BTC)2 and Fe(BTC). The yield of the target product over the investigated catalysts in Knoevenagel condensation increases in the following sequence: (Al)beta < (Al)UTL < (Ga)UTL < (Fe)UTL < Fe(BTC) < (B)UTL < Cu3(BTC)2 being mainly related to the improving selectivity with decreasing strength of active sites of the individual catalysts. The catalytic performance of Fe(BTC), containing the highest concentration of Lewis acid sites of the appropriate strength is superior over large-pore zeolite (Al)beta and B-, Al-, Ga-, Fe-substituted extra-large pore zeolites UTL in Prins reaction of β-pinene with formaldehyde and Pechmann condensation of 1-naphthol with ethylacetoacetate.
Highlights
Condensation reactions, in which a carbonyl group undergoes nucleophilic attack by the enol form or enolate carbanions, are powerful tools to form C-C bonds affording for easy preparation of useful organic compounds (Li, 2005)
alumosilicate zeolite (Al)-substituted zeolites beta and UTL were characterized by the lowest selectivity (20%, Figure 5B) due to a rapid hydrolysis of the target ether III on strong Brønsted acid sites followed by dicarboxylation with the formation of sideproduct IV (Scheme 5)
Catalytic performance of extra-large pore germanosilicate UTL zeolites prepared by incorporation of different heteroelements (e.g., B, Al, Ga, following sequence: (B) < (Fe)) into the framework in Knoevenagel, Pechmann, Prins reactions was investigated and compared with that of large-pore aluminosilicate zeolite beta and Cu, Fecontaining metal-organic-frameworks
Summary
Condensation reactions, in which a carbonyl group undergoes nucleophilic attack by the enol form or enolate carbanions, are powerful tools to form C-C bonds affording for easy preparation of useful organic compounds (Li, 2005). The catalytic performance of Fe(BTC), containing the highest concentration of Lewis acid sites of the appropriate strength is superior over large-pore zeolite (Al)beta and B-, Al-, Ga-, Fe-substituted extra-large pore zeolites UTL in Prins reaction of β-pinene with formaldehyde and Pechmann condensation of 1-naphthol with ethylacetoacetate.
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