Flow Chemistry
Laboratory Capabilities and Reactor Infrastructure
The laboratory is well-equipped to carry out a wide range of liquid–liquid and gas–liquid reactions using various microreactor platforms. Available reactor systems include:
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Photoreactor (Hg lamp) – 10 mL capacity; up to 80 °C and 10 bar
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PFA Tube Reactor – 2 mL to 16 mL; up to 150 °C and 15 bar
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SS316 Tube Reactor – 4 mL to 10 mL; up to 250 °C and 50 bar
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Hastelloy Tube Reactor – 10 mL; up to 250 °C and 50 bar
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Static Mixer Tube Reactor – 20 mL; up to 80 °C and 10 bar
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Column Reactors (6 mm and 10 mm ID) for heterogeneous catalysis; up to 80 °C and 10 bar
Customized reactor systems can be developed to accommodate specific experimental needs and scale-up requirements.
Accessories and Instrumentation
The laboratory also houses a range of essential flow chemistry accessories, including:
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Syringe pumps and dual-channel continuous syringe pumps (up to 20 bar)
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HPLC pumps (up to 100 bar)
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Precision temperature baths
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Back pressure regulators (BPRs)
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High-accuracy temperature sensors
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Flow Chemistry Expertise
The group has successfully developed several chemistries in continuous flow, particularly leveraging photochemical methods. Key transformations include:
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Photochemistry: Cross-electrophile coupling
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Photobromination: Br-OTBN
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Azidation: Cyanuric triazide
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Methoxylation: 2,4-DNAN
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C-Nitration: TATB, TNT, DNT
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O-Nitration: Nitrate esters
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Ammonolysis: Picramide
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Photooxidation: Olefins to aldehydes/ketones
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Suzuki Coupling
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Nitrite Formation: Aliphatic nitrites
Several pharmaceutical and agrochemical intermediates have been synthesized in flow using photochemical techniques developed by the group.
Vapor Phase Chemistry
The laboratory is equipped with high-pressure, high-temperature fixed-bed reactor systems capable of operating under vapor-phase, trickle-bed, and liquid-phase conditions. Key reaction developments include:
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CO₂ to methanol
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Furfural to furan
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N-alkylation
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Isomerization
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Nitration
As with liquid-phase systems, these reactors can also be tailored to meet specific research and process requirements.
Representative Publications:
1. Synthesis of CTA and DNAN using flow chemistry
Mittal, A. K.;† Prakash, G.;† Pathak, P.;† Maiti, D. Asian J. Org. Chem., 2022, 11, e202200444
2. Synthesis of picramide using nitration and ammonolysis in continuous flow
Mittal, A. K.;† Prakash, G.;† Pathak, P.;† Maiti, D. Chem Asian J., 2023, 18, e202201028.
3. Continuous flow synthesis of tert-butyl nitrite and its applications as nitrating agent
Mittal, A. K.;† Prakash, G.;† Pathak, P.;† Dutta, B.; Ahalyan, N.; Maiti, S.; Maiti, D. Org. Process Res. Dev., 2023, 28, 1510.
4. Highly scalable and inherently safer preparation of di, tri and tetra-nitrate esters using continuous flow chemistry
Mittal, A. K.;† Pathak, P.;† Prakash, G.;† Maiti, D. Chem. Eur. J., 2023, 29, e202301662.
5. Highly scalable photoinduced synthesis of silanols via untraversed pathway for chlorine radical (Cl•) generation
Saha, A.; Ali, W.; Werz, D. B.; Maiti, D. Nat. Commun., 2023, 14, 8173.
6. A Scalable Continuous Photo-Flow Protocol for Anaerobic Oxidative Cleavage of Styrenes
Prakash, G.;† Grover, J.;† Pathak, P.;† Mittal, A. K.; Balasubramaniam, P.; Maiti, D. React. Chem. Eng., 2024, 9, 1032.
7. Photoinduced [3+2] Cycloaddition of Carbenes and Nitriles: A Versatile Approach to Oxazole Synthesis
Saha, A.; Sen, C.;† Guin, S.;† Das, C.; Maiti, D.; Sen, S.; Maiti, D. Angew. Chem. Int. Ed., 2023, 62, e20230891.
8. Scalable photoinduced cycloaddition for synthesis of biorelevant oxazoles
Saha, A.; Bianchi, M.; Casali, E.; Maiti, D. Org. Lett., 2025, 27, 6122.