Table 2. Screening of different solvent mixtures under optimized reaction conditionsa.
| Entry | Solvent | Products yield (a, b, c) |
|---|---|---|
| 1 | Ethanol/H2O | <1%, 97%, 54% |
| 2 | Methanol/H2O | <1%, 68%, 13% |
| 3 | Dioxane/H2O | <1%, 64%, 20% |
| 4 | Xylene | No reaction |
| 5 | Dioxane | No reaction |
| 6 | Acetonitrile | No reaction |
| 7 | H2O | <1%, 15%, <1% |
| 8 | Ethanol | <1%, 40%, 10% |
a
Reaction conditions: catalysts (PdO@MCM-41), substrate (0.1 mmol, 21.4 mg), catalyst amount (20 mg, 1.7 mol% Pd), ethanol/water (1 : 1), temperature (120 °C), reaction time (6 hours). Results were screened with GC-FID using mesitylene as an internal standard.