Synthesis of methyl orange using ionic liquids

Two ionic liquids were synthesized, each system consisting of the 1-hexyl-3-methylimidazolium ion ([hmim](+)) as the cation and either hexafluorophosphate ([PF6](-)), or perchlorate ([ClO4](-)) as the anions. This study involves the synthesis of methyl orange (4-[[(4-dimethylamino)phenyl]-azo] benzene sulfonic acid sodium salt) using the ionic liquids as replacement solvents for the reaction. The advantage of using ionic liquids as substitutes for organic solvents includes: recyclable/reclaimable solvents, stabilization of intermediates and higher product yields. The 1-hexyl-3-methylimidazolium derivatives can be used for syntheses conducted at low temperatures and are less toxic than typical organic solvents. (C) 2003 Elsevier Ltd. All rights reserved.