Table 1. Effect of Different Catalysts on HMF Conversion and DFF Yield in AcOHa.
| entry | catalyst, loading (mol %) | T (°C) | time (h) | conv. HMF (%) | yield DFF (%) | select.b (%) |
|---|---|---|---|---|---|---|
| 1 | Fe(NO3)3·9H2O, 5 | RT | 8 | 100 | 93 | 93 |
| 2 | Fe(NO3)3·9H2O, 5 | 50 | 5 | 100 | 95 | 95 |
| 3 | Fe(NO3)3·9H2O, 2 | 50 | 5 | 84 | 78 | 93 |
| 4 | 50 | 5 | 2 | 1 | 50 | |
| 5 | Fe(acac)3, 5 | 50 | 24 | 2 | 1 | 50 |
| 6 | FeCl3·6H2O, 5 | 50 | 24 | 2 | 1 | 50 |
| 7 | Cu(NO3)2·3H2O, 5 | 50 | 5 | 81 | 80 | 99 |
| 8 | Cu(NO3)2·3H2O, 7.5 | 50 | 5 | 100 | 99 | 99 |
| 9 | Al(NO3)3·9H2O, 5 | 50 | 5 | 95 | 93 | 98 |
| 10 | Zn(NO3)2·6H2O, 5 | 50 | 5 | 78 | 72 | 92 |
| 11 | Zn(NO3)2·6H2O, 7.5 | 50 | 5 | 100 | 97 | 97 |
| 12 | KNO3, 10 | 50 | 5 | 49 | 57 | 96 |
| 13 | KNO3, 15 | 50 | 5 | 64 | 61 | 95 |
| 14 | NaNO3, 10 | 50 | 5 | 51 | 49 | 96 |
| 15 | NaNO3, 15 | 50 | 5 | 64 | 62 | 97 |
| 16 | HNO3, 5 | 50 | 5 | 72 | 71 | 99 |
| 17 | HNO3, 15 | 50 | 5 | 100 | 98 | 98 |
a
Reaction conditions: HMF (1 mmol, 126 mg), TEMPO (0.05 mmol, 7.8 mg), 50 °C, AcOH (2 mL), and oxygen balloon; the conversion and yield were determined by HPLC. Conv. = conversion. Select. = selectivity.
b
S (DFF) = yield (DFF)/conversion (HMF).