Enhanced acidity and activity of aluminum/gallium-based ionic liquids resulting from dynamic anionic speciation

Kai Li, Hemant Choudhary, Manish Kumar Mishra, Robin D. Rogers

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

To explore if the catalytic activity of single-metal species in halometallate catalysts can be enhanced with mixed-metal species, aluminum and gallium were simultaneously introduced to prepare a mixed-metal ionic liquid (IL) through a one-pot reaction of [HN222]Cl, AlCl3, and GaCl3 in various amounts. The Lewis acidity in Friedel-Crafts acylation and alkylation reactions of these IL compositions were evaluated and all mixed-metal [HN222][xAlCl3 + (2-x)GaCl3]Cl ILs exhibited higher catalytic activity than AlCl3, GaCl3, [HN222][Al2Cl7], or [HN222][Ga2Cl7]. The broadening in 27Al nuclear magnetic resonance (NMR) of these ILs indicates the presence of dynamic anionic species, whereas matrix-assisted laser-desorption ionization time-of-flight (MALDI-TOF) and acetonitrile-probed Fourier transform infrared (FT-IR) analyses correlates the structure-activity relationship, for instance, identifying the presence of mixed-metal-containing [Cl2GaOClAlClOGaCl2]- species in the better-performing ILs.

Original languageEnglish
Pages (from-to)9789-9793
Number of pages5
JournalACS Catalysis
Volume9
Issue number11
DOIs
StatePublished - Nov 1 2019

Keywords

  • Friedel-Crafts acylation/alkylation
  • Lewis acid catalyst
  • chloroaluminate
  • chlorogallate
  • double salt ionic liquids

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