Table 2. Optimization of the Bioglycerol-Based Carbon Sulfonic Acid Catalyst.
entry | catalyst (5 mol %) | solvent | time (minutes) | yield (%)a |
---|---|---|---|---|
1 | carbon–SO3H | H2O | 30 | 65 |
2 | carbon–SO3H | CH3OH | 30 | 50 |
3 | carbon–SO3H | C2H5OH | 10 | 95 |
4 | carbon–SO3H | 5 | 95 | |
5 | carbon–SO3H | C2H5OH | 5 | 90 |
6 | carbon–SO3H | C2H5OH: H2O | 15 | 93 |
7b | carbon–SO3H | 10 | 70 |
Isolated yield after the purification.
Catalyst (10 mol %).