Highly Selective Separation of Minimum‐Boiling Azeotrope Toluene/Pyridine by Nonporous Adaptive Crystals of Cucurbit[6]uril

Abstract

The production of high purity toluene and pyridine is of significance in both industrial production and synthetic chemistry. The present protocols available to separate toluene/pyridine mixtures are several energy‐intensive distillation methods, which are not environmentally friendly and cost‐effective. Herein, we provide an energy‐efficient and simple adsorptive separation protocol using nonporous adaptive crystals of cucurbit[6]uril (Q[6]). Q[6] crystals separate pyridine from toluene/pyridine mixtures with nearly 100 % purity. Furthermore, removal of the guest from guest‐loaded Q[6] leads to the guest‐free cucurbit[6]uril, which can be recycled without losing performance.

Selective complexation and efficient separation of cis/trans-1,2-dichloroethene isomers by a pillar[5]arene

“…[11][12][13][14] Recently, a novel class of macrocycle-based crystalline materials, termed as nonporous adaptive crystals (NACs) of pillar[n]arenes, has shown interesting adsorption/separation properties. [15][16][17][18][19][20][21] Subsequently, some new NACs based on other important macrocycles 22 such as biphen[n]arene, 23 leaning towerarene, 24,25 tiararene, 26 geminiarene, 27 hybrid [3]arene, 28 naphthotubes 29 and cucurbit [6] uril 30 have been developed. In comparison with traditional porous materials, which usually possess large surface area, NACs are nonporous and structurally adaptive in the initial crystalline state.…”

Advances in applied supramolecular technologies

“…28(a-c). 174 Toluene and pyridine are both important solvents, and are also used in polymer production and for catalysis. The industrial preparation of toluene is often contaminated with pyridine impurities which, similarly to the previous examples, are problematic to remove through distillation.…”

Potential Applications of Cucurbit[n]urils and Their Derivatives in the Capture of Hazardous Chemicals

“…More importantly, entrapment experiments demonstrate that Cy 2 Q[6] powder possesses an outstanding capability to capture gaseous aniline. Huang and co‐workers also successfully utilized a nonporous supramolecular organic framework (SOF) of Q[6] (Q[6]‐based SOF) to adsorb pyridine (Py) from a mixture of toluene/Py [23] . Although the crystalline Q[6]‐based solid material recrystallized from a 4 m solution of HCl is nonporous, it can still form a host–guest inclusion complex with Py in the solid state, whereas toluene cannot be encapsulated into the cavity (Figure 4).…”