Preparation of functionalized porous silica by ultrasonic technique for the methylation reaction of phenol with dimethyl carbonate

Porous silica modified with -(CH2)(3)NH2 (primary amine), -(CH2)(3)NHCH2CH2NH2 (secondary/primary amine) and -(CH2)(3)N-cycl-(CH2)(4) (tertiary amine) were synthesized by ultrasonic technique under mild conditions. The samples were characterized by BET, elemental analysis and TG, showing that the organosilane moieties were grafted onto the surface of porous silica by covalent bond. The structure of the organosilane moieties and ultrasonic treatment time were all significant for the quantities of grafted amino groups. The samples exhibited promising catalytic properties towards the methylation reaction of phenol with dimethyl carbonate (DMC). The methylation reaction with the modified samples featured high selectivity at high conversion. The samples were subjected to utilization for a few recycles without obvious loss of activity to indicate that ultrasonic technique was effective for the preparation of organically modified porous silica catalysts.