Highly selective aldol condensation using amine-functionalized SiO2-Al2O3 mixed-oxide under solvent-free condition

Article abstract of DOI:10.1002/cjoc.201090346

A series of amine catalysts supported on mesoporous molecular sieves SiO₂/Al₂O₃ with trimethoxysilylpropylamine [(CH₃O)₃Si(CH₂)₃NH₂] loading varying from 3 mmol to 6 mmol were synthesized by impregnation method. The aldol condensation of various aromatic aldehydes and 1-heptanal was used to test the acid-base cooperativity of amine-functionalized SiO₂/Al₂O₃. The effects of solvent, reaction temperature, benzaldehyde to 1-heptanal molar ratio, different supports (SiO₂, Al₂O₃ and SiO₂-Al₂O₃), catalyst amount and recyclability of the catalyst were investigated. Sample containing 5 mmol amine loaded showed highest benzaldehyde conversion (100%) and selectivity (97%) for jasminaldehyde.