Near-Perfect Purification of 2,6-Xylenol from Ternary Cresol Mixtures Using Cucurbit[7]uril

The separation of <i>m</i>-cresol (<i>m</i>-cre), <i>p</i>-cresol (<i>p</i>-cre), and 2,6-xylenol (2,6-xyl) poses a significant challenge in industrial processes. This study focuses on selectively separating <i>m</i>-cre and <i>p</i>-cre from a ternary mixture using a cucurbit[7]uril (Q[7]) aqueous solution to achieve the near-perfect purification of 2,6-xyl. Experimental results show that <i>m</i>-cre and <i>p</i>-cre can be selectively encapsulated by the Q[7] host, while 2,6-xyl, due to its larger volume, cannot be encapsulated. The synergistic effect of steric hindrance and complex stability contributes to effective host–guest selective encapsulation separation. The Q[7] aqueous solution can be easily recovered and reused without a significant decrease in separation performance. In the simulated industrial separation experiment, the purity of the purified cresol reached 100%. This research underscores the importance of macrocyclic host molecules in enhancing industrial separations and reducing energy costs through precise guest molecule recognition.