Synthesis of liquid crystals using Suzuki–Miyaura coupling reactions using mesoporous,ligand-free Pd/Si3N4 catalysts in aqueous media

We report a ligand-free Pd/Si₃N₄ catalysed Suzuki–Miyaura aryl–aryl cross-coupling reaction using mixtures of water-miscible solvents, such as dimethoxyethane, ethanol and isopropanol with water and several bases, such as sodium carbonate and potassium phosphate. The reaction time and catalyst concentration were optimised and the heterogeneous nature of the reaction was investigated. The optimised reaction conditions were used to synthesise a standard liquid crystal using environmentally friendly solvents and a Pd/Si₃N₄ catalyst. This reaction is scalable to produce larger quantities.