Recycling of Phosphorus-Based Organocatalysts by Organic Solvent Nanofiltration

Organic solvent nanofiltration has been studied as an efficient and mild tool for the separation of phosphorus-based organocatalysts and their subsequent recycling. The atom-economic conversion of butylene oxide with carbon dioxide has been chosen as a test reaction, yielding the desired cyclic carbonate in excellent yields under mild conditions. The utilization of modern solvent-resistant membranes to separate and recycle the organocatalyst from reaction media was established. Commercially available membranes with molecular weight cut-offs between 150 and 500 g·mol–1 were employed. DuraMem 300 proved to be the best membrane, showing excellent rejections of up to 99% for the organocatalyst in the recycling experiments. The catalyst and the membrane were reused in four consecutive reactions without the loss of activity and selectivity, respectively.