Synthesis of a reusable oxotungsten-containing SBA-15 mesoporous catalyst for the organic solvent-free conversion of cyclohexene to adipic acid

An oxotungsten–silica mesoporous structure (WSBA-15) has a hierarchical crystalline architecture in which the W dopants possess tetrahedral coordination geometries for the mixed-valence states W6+, W5+, and W4+. The WSBA-15 catalyst can be recycled—without any loss of activity—for the direct oxidation (30% H2O2) of cyclohexene to colorless, crystalline adipic acid (55% yield) under organic solvent-free conditions.