Amar Flow Laboratory, in collaboration with a multinational agrochemical company successfully developed a proof-ofconcept trial for the nitration of a substituted aromatic compound continuously. This innovative continuous flow process presents several advantages over traditional batch processing methods, promising significant improvements in efficiency, product quality, and safety.
To compare both the reactors, a nitration reaction was chosen as the model reaction. The reaction involved 50 mL 3/8” PinchFLO™ and CorFLO® reactors, and a comparative study was conducted on different flow reactors with respect to a 50 mL plain tube of the same dimensions.
The conversion of the starting material and selectivity towards the dinitrated product were monitored. The starting materials were pumped using appropriate syringe pumps to the reactor. The system concluded with a cooler and a back pressure regulator (BPR). The organic layer was analyzed using Gas Chromatography.
70% Nitric acid (sourced from Sigma-Aldrich), Substituted aromatic compound (>99% Purity, confirmed by GC, sourced from the Client), Dichloromethane (>99.8%, sourced from Sigma-Aldrich).
(At a constant back pressure of 2 bar, Mol ratio of substituted aromatic compound : HNO₃ = 1 : 2.5)
| Total Flow Rate (mL/min) | Residence Time (min) | Temperature (°C) | % Conversion* | % Selectivity# | % Yield# |
|---|---|---|---|---|---|
| Plain Tube Reactor (50 mL) | |||||
| 100 | 0.5 | 50 | 63.64 | 31.84 | 20.26 |
| 50 | 1 | 50 | 69.25 | 44.57 | 30.86 |
| 33.33 | 1.5 | 50 | 74.32 | 45.78 | 34.02 |
| 100 | 0.5 | 70 | 45.46 | 35.83 | 16.29 |
| 50 | 1 | 70 | 48.84 | 38.94 | 19.02 |
| 33.33 | 1.5 | 70 | 49.92 | 41.53 | 20.73 |
| PinchFLO™ Reactor (50 mL) | |||||
| 100 | 0.5 | 50 | 87.64 | 54.07 | 47.38 |
| 50 | 1 | 50 | 94.87 | 71.98 | 68.28 |
| 33.33 | 1.5 | 50 | 95.55 | 87.31 | 83.42 |
| 100 | 0.5 | 70 | 81.41 | 47.82 | 38.93 |
| 50 | 1 | 70 | 83.27 | 72.89 | 60.70 |
| 33.33 | 1.5 | 70 | 89.82 | 75.62 | 67.92 |
| CorFLO® Reactor (50 mL) | |||||
| 100 | 0.5 | 50 | 92.67 | 65.33 | 60.54 |
| 50 | 1 | 50 | 94.54 | 90.35 | 85.42 |
| 33.33 | 1.5 | 50 | 99.83 | 92.30 | 92.14 |
| 100 | 0.5 | 70 | 84.67 | 68.93 | 58.36 |
| 50 | 1 | 70 | 90.87 | 89.75 | 81.56 |
| 33.33 | 1.5 | 70 | 91.34 | 90.54 | 82.70 |
This study highlights the advantages of using advanced flow reactors like the PinchFLO™ and CorFLO® for continuous chemical processes. Both reactors significantly outperformed the plain tube reactor in terms of conversion, selectivity, and yield.
The CorFLO® reactor, in particular, emerged as the optimal choice for the nitration of substituted aromatic compounds, offering unparalleled performance due to its innovative design and enhanced mixing and heat transfer capabilities.
These findings underscore the potential of flow chemistry to replace traditional batch processes, ensuring better efficiency, safety, and scalability for industrial applications. Further studies on process optimization and scale-up using the CorFLO® reactor are recommended for industrial implementation.
