Table 2. Ionic liquids as solvents and catalysts.
| Entry | Catalyst mol% | Reusability | Medium | T, °C | Time | Yield, % | Ref. |
|---|---|---|---|---|---|---|---|
| 1 | Yb(OTf)3 (20) | No | Solvent-free | 80 | 4–12 h | 35–92 | 106 |
| 2 | ([TEBSA][H2SO4]) (5) | No | Solvent-free | 120 | 10–45 | 73–91 | 55 |
| 3 | ([Hmin]HSO4) (10) | Not reported | Solvent-free | 115 | 15–30 | 78–93 | 107 |
| 4 | Imidazolium salts (10) | No | Solvent-free | 120 | 1–40 | 81–96 | 45 |
| 5 | (PEG-DAIL) (3) | No | Solvent-free | 80 | 3–15 | 81–98 | 56 |
| 6 | [Tmim] [HSO4 ]4 (1.25) | No | Solvent-free | 90 | 3–15 min | 90–96 | 108 |
| 7 | ([Et3NH][HSO4]) (20) | Yes (3) | Solvent-free | 70 | 2–25 min | 65–85 | 109 |
| 8 | {[TMEDSA][Cl]2} (7.5) | No | Solvent-free | 70 | 15–25 min | 92–95 | 93 |
| 9 | (SO3H) (n-Bu)3P+ FeCl4− (1) | No | Solvent-free | 45 | 5–30 min | 75–94 | 110 |
| 10 | [CholineCl][ZnCl2]3 (20) | Yes (3) | Solvent-free | 60 | 40–80 min | 45–95 | 111 |