Solvent free aldol condensation of propanal to 2-methylpentenal using solid base catalysts

• Published in: Journal of molecular catalysis. A, Chemical Vol. 278; no. 1; pp. 135 - 144
• Main Authors: Sharma, Sumeet K., Parikh, Parimal A., Jasra, Raksh V.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 14.12.2007; Elsevier
• Subjects: 2-Methylpentenal; Aldol condensation; Catalysis; Cation exchanged zeolites; Chemistry; Exact sciences and technology; General and physical chemistry; Hydrotalcite; Ion-exchange; Kinetics; Propanal; Surface physical chemistry; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Zeolites: preparations and properties; Hydrotalcite; 2-Methylpentenal; Kinetics; Cation exchanged zeolites; Propanal; Aldol condensation; Zeolite; Aldehyde; Base; Solid; Molecular sieve; Heterogeneous catalysis; Solvent free reaction; Alkali metal Ions; Ion exchange; Catalyst; Modified material
• ISSN: 1381-1169; 1873-314X
• DOI: 10.1016/j.molcata.2007.09.002

Catalytic activities of alkali ion-exchanged zeolites, alumina, alkali treated alumina and hydrotalcite having varied Mg/Al molar ratio were evaluated for aldol condensation of propanal in liquid phase under solvent free condition. The maximum conversion (97%) of propanal with 99% selectivity of 2-methylpentenal was observed at 100 °C and 10 h using activated hydrotalcite of Mg/Al molar ratio of 3.5 as a catalyst. ▪ Catalytic activities of alkali ion-exchanged zeolites, alumina, alkali treated alumina and hydrotalcite having varied Mg/Al molar ratio were evaluated for aldol condensation of propanal in liquid phase under solvent free conditions. The maximum conversion (97%) of propanal with 99% selectivity of 2-methylpentenal was obtained at 100 °C and 10 h using activated hydrotalcite of Mg/Al molar ratio of 3.5 as a catalyst. The basicity of the activated hydrotalcite of Mg/Al ratio 1.5, 2.5 and 3.5 was evaluated by isomerization of β-isophorone to α-isophorone as a model test reaction reported for basicity measurement. The effect of amount of catalyst and temperature on the conversion of propanal, selectivity of 2-methylpentenal and initial rate of reaction were studied in detail. The activation energy for propanal condensation under solvent free condition was found to be 58 kJ using activated hydrotalcite of Mg/Al molar ratio 3.5 as a catalyst. The catalyst was recycled six times without any significant loss in conversion and selectivity.