Catalytic chlorination of 2-chlorotoluene with gaseous chlorine to 2,6-dichlorotoluene over AlCl3, FeCl3, ZnCl2, and [BMIM]Cl–nAlCl3 (–2FeCl3 and –2ZnCl2) catalysts

Abstract

Catalytic chlorination of 2-chlorotoluene (OCT) with Cl2 to dichlorotoluene (DCT) over metal chlorides and Lewis acid ionic liquids was investigated. The catalytic activities of the metal chlorides for the selective chlorination of OCT to high value 2,6-DCT were in the order of AlCl3 > FeCl3 > ZnCl2. When the weight ratios of AlCl3 to OCT were 0.5:100–2:100 at 10–30 °C for 12 h, the selectivity of 2,6-DCT was kept at ca. 33 %. The catalytic activities of the ionic liquids for the selective chlorination of OCT to 2,6-DCT were in the order of [BMIM]Cl–AlCl3 < [BMIM]Cl–2ZnCl2 < [BMIM]Cl–2FeCl3 < [BMIM]Cl–2.5AlCl3 < [BMIM]Cl–2AlCl3. When the weight ratio of [BMIM]Cl–2AlCl3 to OCT was 2:100 at 10–30 °C for 12 h, the selectivity of 2,6-DCT was kept at ca. 34 %. As compared with the metal chlorides, the ionic liquids exhibited high catalytic activities for the chlorination of OCT to DCT, correspondingly.