Highly efficient separation of pyrrolidine and tetrahydrofuran by using solid crystal powder of Cucurbit[6]uril

Abstract

Pyrrolidine is a significant chemical industry product and obtaining high-purity pyrrolidine holds considerable importance in both industrial and laboratory environments. Pyrrolidine is conventionally synthesized through the catalytic reaction of tetrahydrofuran (THF) and ammonia under gas phase conditions and the product obtained contains both pyrrolidine and THF. The close boiling points of pyrrolidine and THF make their separation extremely difficult. Current methods for separating mixtures of pyrrolidine and THF are complicated, energy-intensive and low separation efficiency. In this study, we provide a simple and efficacious methodology for the separation of pyrrolidine and THF mixtures, utilizing solid crystal powder of cucurbit[6]uril (Q[6]). The Q[6] separates pyrrolidine from a pyrrolidine/THF mixture with 99.0 % purity in the solid–vapor phase and 97.0 % purity in the solid − liquid interface. Satisfactory separation outcomes were still achieved by simulating the separation of real industrial samples. In addition, the Q[6] exhibits notable recyclability owing to its reversible transition between the guest-loaded Q[6] and guest-free Q[6] structures. After purification, the Q[6] can be reused again without affecting its performance.