Abstract
Two solid Lewis acids, namely Sn-Beta and Sn-MCM-41, have been applied to the Carbonyl- Ene reaction of β-pinene and α-methylstyrene with paraformaldehyde. For the more bulky molecule β-pinene the mesoporous material Sn-MCM-41 has been found to be the better catalyst whereas for the smaller α-methylstyrene Sn-Beta has shown a higher activity. Best selectivities have been observed in nitrile solvents, such as acetonitrile and butyronitrile, whereas reactions in toluene or dioxane have been less selective. The catalysts are water resistant what has been evidenced by addition of up to 200 wt% (with respect to the catalyst) of water without loss of activity or selectivity. Sn-MCM-41 has been employed in several cycles with intermediate regeneration, always recovering the high activity.
Highlights
Nopyl acetate (4) is an artificial fragrance compound with a fresh-fruity-woody odour.[1]. In industry it is prepared by a Carbonyl-Ene reaction of β-pinene (1) and paraformaldehyde (2) with subsequent acetylation of the intermediary nopol (3) with acetic anhydride (Scheme 1)
In other words we have achieved in one cycle using the Sn-MCM-41 catalyst practically the same number of moles per mg of catalyst as obtained with the chemical vapour deposition (CVD) material prepared with
Activity measured by the turnover number (TON), i.e. mol of substrate converted per mol of tin, indicated a much higher activity of the Sn-MCM-41 produced by direct synthesis
Summary
Nopyl acetate (4) is an artificial fragrance compound with a fresh-fruity-woody odour.[1]. We want to report on the application of Sn-Beta and Sn-MCM41 to the intermolecular carbonyl-Ene reaction between β-pinene or α-methylstyrene with paraformaldehyde. It was possible to incorporate more Sn into the MCM-41 material and the reaction time could be shortened further, but a decrease in product selectivity occurred.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call