Soccer-ball-shaped carbon molecules separate organic compounds
doi:10.1038/nindia.2014.144 Published online 30 October 2014
Researchers have developed a technique that employs fullerene, a molecule shaped like a soccer ball and consisting of 60 carbon atoms, and organic solvents to selectively capture and hence separate different organic compounds based on their shapes1. This technique is potentially useful for separating industrially important organic compounds from crude oil.
Isomers are compounds with the same chemical formula but different structures. As isomers generally exhibit similar physical properties, it can be extremely difficult to separate them. Existing techniques that use zeolites and metal–organic frameworks are expensive and inefficient. The researchers devised effective techniques for separating organic isomers by employing two methods: liquid–liquid interfacial precipitation and ultrasonic liquid–liquid interfacial precipitation.
They tested the efficiencies of these two methods in separating isomers of xylene and trymethylbenzene using organic solvents and fullerene molecules. They performed the experiments at different temperatures to evaluate the separation efficiencies of fullerenes for different isomers.
The researchers found that both methods very efficiently separated meta-xylene, an isomer of xylene from other xylene isomers. The efficiency and separation time depended on the temperature. Liquid–liquid interfacial precipitation exhibited higher separation efficiencies than its ultrasonic counterpart.
The xylene molecules were trapped inside the cavities of fullerene molecules. At 70°C, the fullerene molecules released the xylene molecules, resulting in a weight loss of 10.2%. This sufficiently low-temperature release of captured organic isomers ensured that the fullerene remained pure, allowing it to be used in the next separation cycle.
The methods also efficiently separated isomers of trimethylbenzene. The researchers say that fullerene molecules were able to isolate the organic isomers with almost 100% purity, making the methods suitable for industrial applications at near-ambient conditions.
1. Rana, M. et al. C60-mediated molecular shape sorting: separation and purification of geometrical isomers. Angew. Chem.Int. Ed. (2014) doi: 10.1002/anie.201408981