Molecularly Imprinted Polymers for (Thio)urea Organocatalyst Recovery and Recycling

The strong binding affinity of carboxylate-based ion pair monomers toward ureas and thioureas (>10(5) L mol(-1) in DMSO-d(6)) has been utilized to prepare organocatalyst-selective molecularly imprinted polymers for the first time. These polymers exhibited exceptionally strong binding for the organocatalyst targets and were applied in the reversible capture of Schreiner's urea and thiourea from reaction mixtures. Recyding and reuse of these precious homogeneous catalysts is achieved using rapid and straightforward solid-phase extraction protocols. Catalyst recoveries of up to 98% from Diels-Alder and Baylis-Hillman reactions are demonstrated, while the polymers themselves are stable for at least 100 extraction cydes without loss of performance.

Automated summary

In this study, organocatalyst-selective molecularly imprinted polymers were successfully prepared using strong binding affinity. These polymers demonstrated exceptional binding for the organocatalyst targets and were able to reversibly capture the desired compounds from reaction mixtures. Rapid and straightforward solid-phase extraction protocols allowed for efficient catalyst recovery and reuse.