Table 1.
Optimization of reaction parameters.
| Entry | Ty (mM) | Ascorbic Acid (mM) | Residence Time (min) | m.c. (%) |
|---|---|---|---|---|
| 1 a | 20 | 40 | 60 | 25 |
| 2 b | 20 | 40 | 60 | 40 |
| 3 c | 20 | 40 | 60 | 47 |
| 4 c | 20 | 100 | 60 | 48 |
| 5 c | 10 | 50 | 60 | 76 |
| 6 c | 10 | 50 | 30 | 78 |
| 7 c | 10 | 50 | 15 | 50 |
The solutions of Ty and ascorbic acid have been prepared in sodium phosphate buffer 0.1 M, pH 7.0. The free tyrosinase was added to the ascorbic acid solution (300 U/mL). The reactions have been performed at 28 °C. Conversions have been determined by 1H NMR after in-line extraction with toluene, phase separation and evaporation of the solvent, considering diagnostic signal at 7.05–6.99 for Ty and signal at 6.71–6.64 for HTy. a Reactor: 10 mL PTFE coil; b reactor: 15 mL tube-in-tube reactor; c reactor: 10 mL PTFE coil; air/liquid segmented flow; m.c. = molar conversion.