Highly selective synthesis for 4,4′-bisphenol F from phenol and formaldehyde catalyzed with [C4mim][HSO4] ionic liquid

Based on the hydrogen bonding formed between the phenolic hydroxyl group and the C2-position hydrogen of imidazolium cation in the hydrophilic imidazole-based ionic liquid, [C4mim][HSO4] ionic liquid as solvent and catalyst was used for the highly selective synthesis of 4,4′-bisphenol F from phenol and formaldehyde under the reaction condition of low phenol/formaldehyde ratio and low reaction temperature, which is significant in reducing energy consumption for the production of 4,4′-bisphenol F in industry application.