Regioselective mononitration of aromatic compounds using Brønsted acidic ionic liquids as recoverable catalysts

Some novel acyclic Brønsted acidic task-specific ionic liquids (TSILs) that bear an alkane sulfonic acid group in an acyclic trialkanylammonium cation were synthesized and their uses as halogen-free catalysts for regioselective mononitration of aromatic compounds were investigated. The reactions were carried out at 60–80 °C with reasonable to good yields and improved para-selectivities for halogenobenzenes compared to those in the absence of the catalysts. In addition, the TSILs could be recovered and reused without noticeably decreasing the catalytic activity.

Graphical abstractThe regioselective mononitration of aromatic compounds was carried out at 60–80 °C, catalyzed by recyclable acyclic Brønsted acidic task-specific ionic liquids that bear an alkane sulfonic acid group in an acyclic trialkanylammonium cation with reasonable to good yields. Para-selectivities for halogenobenzenes were improved compared to those in the absence of the catalysts.Figure optionsDownload full-size imageDownload as PowerPoint slide