| Summary: | Ionic liquids with [BMIM], [Et<sub>3</sub>NH], and [BPy] cations and Al<sub>n</sub>Cl<sup>−</sup><sub>3n+1</sub>, Zn<sub>n</sub>Cl<sup>−</sup><sub>2n+1</sub>, and Cu<sub>n</sub>Cl<sup>−</sup><sub>n+1</sub> anions were used as the catalysts for the chlorination of toluene with Cl<sub>2</sub>. The Zn<sub>n</sub>Cl<sup>−</sup><sub>2n+1</sub> containing ionic liquids with high Lewis acid strength had high catalytic activity for the selective chlorination of toluene to <i>o</i>-chlorotoluene via the electrophilic substitution reaction. Dichlorotoluenes were favorably formed when the Al<sub>n</sub>Cl<sup>−</sup><sub>3n+1</sub> containing ionic liquids with both Lewis and Brönsted acid sites were used as the catalysts. When the Cu<sub>n</sub>Cl<sup>−</sup><sub>n+1</sub> containing ionic liquids with weak Lewis acid strength were used as the catalysts, more benzyl chloride was formed via the radical chlorination of methyl group. When the [BMIM]Cl-2ZnCl<sub>2</sub> ionic liquid was used as the catalyst, after reacting at 80 °C for 8 h, the conversion of toluene was 99.7% and the selectivities of <i>o</i>-chlorotoluene, <i>p</i>-chlorotoluene, <i>m</i>-chlorotoluene, benzyl chloride, and dichlorotoluenes were 65.4%, 26.0%, 4.0%, 0.4%, and 4.2%, respectively. The [BMIM]Cl-2ZnCl<sub>2</sub> ionic liquid catalyst had good recycling performance.
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