Use of Mesoporous MCM-41 Aluminosilicates as Catalysts in the Preparation of Fine Chemicals: A New Route for the Preparation of Jasminaldehyde with High Selectivity

Abstract

α-n-Amylcinnamaldehyde (Jasminaldehyde) has been prepared with high selectivity and using low ratios of benzaldehyde/heptanal by means of mesoporous molecular sieve catalysts and a process which involves the acetalization of heptanal with methanol, followed, in the same pot, by a slow hydrolysis of dimethylacetal and the aldolic condensation of the two aldehydes as the final step. A large pore zeolite (Beta) as well as mesoporous silica-aluminas with regular pore sizes such as MCM-41 and SAM have been used as catalysts. The results indicate that mesoporous silica-aluminas with a very narrow range of pore diameter such as MCM-41 are the most adequate catalysts to produce in one pot the three consecutive reactions, avoiding in a very large extent the self-condensation of heptanal and undesired consecutive reactions. This new route allows us to achieve Jasminaldehyde with high selectivity and with a relative high global reaction rates. The influence of the concentration of acid sites on MCM-41, reaction temperature, and molar ratio of the reactants have been also studied.