Table 7.
MW-assisted esterification of valeric acid using different alcohols (MeOH, EtOH, iPrOH, BuOH) and different acid-to-alcohol molar ratios.
| Entry | System | Alcohol | Acid-to-Alcohol Ratio | Conversion to Alkyl Valerate (mol %) | Specific Activity (U/gbiocatalyst) |
|---|---|---|---|---|---|
| 1 2 3 4 |
Blank | MeOH EtOH iPrOH BuOH |
All | No conversion | - |
| 5 6 7 8 |
Support SiO2 | MeOH EtOH iPrOH BuOH |
All | No conversion | - |
| 9 10 11 |
Free enzyme | EtOH | 1:1 1:2 1:3 |
70 75 71 |
270 ± 13 |
| 12 | Biosilicified enzyme | MeOH | All | No conversion | - |
| 13 14 15 |
Biosilicified enzyme | EtOH | 1:1 1:2 1:3 |
58 82 73 |
376 ± 7 |
| 16 17 18 |
Biosilicified enzyme | IPrOH | 1:1 1:2 1:3 |
39 40 37 |
300 ± 13 |
| 19 20 21 |
Biosilicified enzyme | BuOH | 1:1 1:2 1:3 |
79 81 80 |
337 ± 5 |
Reaction conditions: 12% m/v biosilicified enzyme (equal quantity for free enzyme using buffer solution), 100 W, 40 °C, 1 h MW radiation.