Recyclable solid catalysts for epoxidation of alkenes: Amino- and oniumsilica-immobilized [HPO4{W2O2(μ-O2)2(O2)2}]2− anion

摘要: Abstract We designed solid catalysts for liquid-phase epoxidation based on functionalized silica Si(CH 2 ) 3 Q + [Q: NH , NEt NC 5 H PPh ] and [HPO 4 {W O ( μ -O (O }] 2− . The approach that we adopted allowed us to avoid the use of chlorocarbon solvent enabled catalyst recycling. By using supports with different linking chains between anion surface lipophilicities, followed their influence activity in cyclooctene (R)-limonene by t -BuOH. All solids were active (conversion up 100%; epoxide selectivity TOF 2–4 h −1  anion ). degree coverage organic functions was crucial recycling performance. Catalysts low densities hydrophilic surfaces easily deactivated. End-capping improved stability but decreased activity. dense onium groups site a hydrophobic chloropropyl environment demonstrated high excellent stability. Less promising results obtained (R)-limonene.