Comparison of the reaction conditions and results for the synthesis of xanthene.
| Entry | Catalyst | Solvent | Time (min) | Temp. (°C) | Yield (%) | Ref. |
|---|---|---|---|---|---|---|
| 1 | [SO3H–Pyrazine–SO3H]Cl2 | Solvent free | 10 | 100 | 93 | 56 |
| 2 | Fe3O4 nanoparticles | Solvent free | 20 | 100 | 90 | 64 |
| 3 | TCCAa | Solvent free | 40 | 110 | 78 | 65 |
| 4 | [Et3N–SO3H]Cl | Solvent free | 60 | 80 | 97 | 22 |
| 5 | LUS-Pr-SO3Hb | Solvent free | 15 | 140 | 90 | 66 |
| 6 | [Cmmim][BF4] | Solvent free | 120 | 80 | 94 | 67 |
| 7 | ICl3/SiO2 | Solvent free | 60 | 75 | 90 | 68 |
| 8 | NP | EtOH | 6.5 h | Reflux | 90 | 69 |
| 9 | Cu(ii)/NP | EtOH | 120 | Reflux | 98 | 70 |
| 10 | — | EtOH | 24 h | Reflux | — | 71 |
| 11 | Fe3O4@NFC@NNSM-Mn(iii) | EtOH | 10 | 45 | 96 | This work |
a
Trichloroisocyanuric acid.
b
Propyl sulfonic acid functionalized LUS-1 (Laval University silica) (LUS-Pr-SO3H).