Preparation of tetramethylguanidine-functionalized mesoporous silica as a catalyst for the epoxidation of electron deficient alkenes

Abstract

A heterogeneous guanidine catalyst, based on 1,1,3,3-tetramethylguanidine was prepared by functionalisation of a glycidylpropyl group previously attached to hexagonal mesoporous silica. The catalyst was characterized by various techniques including Diffuse Reflectance FTIR, ¹³C NMR, elemental analysis and simultaneous thermogravimetric and differential scanning calorimetry analyses. It was then screened in the epoxidation of electron deficient alkenes. The results obtained show that indeed the intended moiety was attached onto silica surface at a loading of 0.4 mmol per g silica. The parent silica had a surface area of 1511 m² g^-1 which decreased to 1275 m² g^-1 upon functionalisation. The catalyst was active and highly selective in epoxidation of electron deficient alkenes, giving yields up to 60% within 12 hours. The reusability of the catalyst was however limited, calling for further investigation.