Selective inclusion of p-xylene by bis-hydrazone compounds

Abstract

The separation of xylene isomers from their mixture is a challenging task. The present study describes the highly selective inclusion of p-xylene (p-XY) from a mixture of xylene isomers by three novel organic bis-hydrazone compounds, ethanedial-1,2-bis(4,4′-dichlorobenzophenone hydrazone) (1), ethanedial-1,2-bis(4,4′-dibromobenzophenone hydrazone) (2) and ethanedial-1,2-bis(4,4′-diiodobenzophenone hydrazone) (3). These van der Waals host compounds specifically enclathrate p-XY from a mixture of xylene isomers. Crystallization of the host compounds in all possible mixtures of xylene isomers, X-ray diffraction (both single-crystal and powder) and thermogravimetric analysis (TGA) confirm the selective inclusion property of the bis-hydrazone compounds. Compounds 1, 2 and 3 might be suitable candidates for the separation of p-XY from a mixture of xylene isomers.