Lanthanide Coordination Polymers as Heterogeneous Lewis AcidCatalysts for Glycerol Acetalization

Coordination polymers containing lanthanide ions (LnCPs) have received relatively lessattention compared to d-block metal coordination polymers, despite their potential for remarkableluminescence, catalytic activity, and magnetic properties [۱,۲]. LnCPs have shown promise asLewis acid catalysts for various chemical transformations. Lewis acids are electron acceptors thatcan facilitate chemical reactions by accepting electron pairs from other molecules [۳]. The use oflanthanide ions as Lewis acid catalysts is of particular interest, and researchers have been exploringtheir potential in this area [۴]. [Er۲(bpndc)۳(DMF)۲] (۱) and [Yb۲(bpndc)۳(DMF)۲] (۲) weresynthesized by combining Benzophenone-۴,۴'- dicarboxylate (bpndc۲-) linker, Erbium nitratehexahydrate, Ytterbium nitrate hexahydrate, respectively, using a facile solvothermal reaction andcharacterized using single crystal X-ray diffraction, Fourier transforms infrared spectroscopy,Thermogravimetric analysis, Powder X-ray diffraction, and Scanning electron microscopy. Bothcompounds exhibit good thermal and solvent stability. These coordination polymers were used asheterogeneous Lewis acid catalysts for glycerol acetalization. The investigation has focusedlargely on the effect of reaction time and temperature, and catalyst to glycerol molar ratio. Optimalconditions for these two polymers included a duration of ۴ hours, a temperature of ۵۰º C, a molarratio of ۱ to ۱۰ catalyst to glycerol, and a conversion percentage was ۷۷% for [Er۲(bpndc)۳(DMF)۲]polymer and ۷۲% for [Yb۲(bpndc)۳(DMF)۲] polymer. The catalysts leaching, stability, andrecyclability were investigated. This study shows the potential role of the [Er۲(bpndc)۳(DMF)۲]and [Yb۲(bpndc)۳(DMF)۲] as heterogeneous Lewis acid catalysts for glycerol acetalization

Keywords:

Coordination polymers , Lanthanides , Lewis acid catalysts , Acetalization