A Mild and Selective Method for the Catalytic Hydrodeoxygenation of Cyanurate Activated Phenols in Multi-Phasic Continuous Flow.

A low energy, high selectivity approach to the catalytic hydrodeoxygenation of phenols is reported using batch or continuous flow methods to react 3 equivalents of phenol with cyanuric chloride then hydrogenolyzing the triarylcyanurate intermediate to give 3 equivalents of de-oxo aromatic. The use of cyanuric chloride compares favorably with existing activation methods, showing improved scalability, atom efficiency and economics. The scope of both the activation and hydrogenolysis stages are explored using lignin-related phenols. Initial development has identified that continuous stir tank reactors (CSTRs) enable a multi-phasic process for converting guaiacol to anisole, and at steady-state overcome the catalyst deactivation issues observed in batch, seemingly caused by the cyanurate by-product. Green chemistry aspects, and the potential for industrial adoption are discussed.