Ketalization of Ketones to 1,3-Dioxolanes and Concurring Self-Aldolization Catalyzed by an Amorphous, Hydrophilic SiO₂-SO₃H Catalyst under Microwave Irradiation

The amorphous, mesoporous SiO₂-SO₃H catalyst with a surface area of 115 m² g^-1 and 1.32 mmol H⁺ per g was very efficient for the protonation of ketones on a 10% (m/m) basis, and the catalyst-bound intermediates can be trapped by polyalcohols to produce ketals in high yields or suffer aldol condensations within minutes under low-power microwave irradiation. The same catalyst can easily reverse the ketalization reaction.

Keywords:
protonated ketones; self-aldolization; ketalization; ketal hydrolysis; sulfonated silica