A Scalable Balz-Schiemann Reaction Protocol in a Continuous Flow Reactor

Our protocol is a straightforward strategy for preparing aryl fluoride from aryl amine in a continuous flow manner. The is safe, controllable, and efficient. This measure could provide an insight into the fine chemical and the pharmaceutical industry, which could make a safe and a reliable process.

Please be careful and attentive will performing this technique. First, read all the steps and figure out the details of operating before you try this technique. To perform the Balz-Schiemann reaction in a continuous flow system, prepare two modules of the microflow reactor with an internal reaction volume of nine milliliters, and one dynamic mixing tube reactor with an internal reaction volume of 500 milliliters.

Also, prepare one constant flow pump with a PTFE pump head, and three constant flow pumps with the 316 L stainless steel pump head. Assemble the equipment as described in the manuscript. Check the mechanical integrity of all the connections between pumps, pipelines, and flow reactors before use.

Set the flow rates of the pumps. Then set the jacket outlet, temperature of the premixing and diazonium salt formation zone at minus five degrees Celsius and the jacket outlet temperature of the thermal decomposition zone at 60 degrees Celsius to maintain the temperature regulation. To check equipment safety and leakage, first place the dosing pipeline of pumps A, B, C and D into the feed E bottle.

And discharging pipeline into the waste collecting bottle. Then start the pumps and slowly regulate the back pressure up to three bars. Observe the stability of each pump and check all the joints, pipelines, and reactors for any solvent leakage.

Also, check if the jacket inlet and outlet temperature of each zone and the current inlet pressure of each pump are within the target ranges. Then, stop pumps after 10 minutes of steady state equilibrium. To begin the reaction process, place the dosing pipeline's A, B, C and D into the corresponding feeds, and put the discharging pipeline into the waste collection bottle.

Start pumps A and B simultaneously and record the time. Then start pump C after 30 seconds and pump D after 8 minutes. After 10 minutes of steady state equilibrium, place the discharging pipeline into the product collection vessel.

Observe and record the temperature of each zone and the pressure of each pump. Once feed B pumping is complete, insert the dosing pipeline B into feed E.Then put the discharging pipeline into a waste collection bottle. And dosing pipeline's, A, C and D into the feed E bottle.

Turn off pumps A, B, C, and D after 10 minutes of washing. A continuous flow reactor was successfully applied to the Balz-Schiemann reaction on a model substrate. The reaction temperature of the flow experiments was successfully controlled at 10 degrees Celsius with 70%crude product purity, which was higher than what was obtained in batch processing.

Almost 98%of conversion was reached in 600 seconds of the resident's time. When the flow rate was 50 milliliters per minute in the diazotization zone, and 5.4 seconds in the thermal decomposition zone, at 100 milliliters per minute flow rate. Increasing the flow rate leaves a large amount of starting material in the reaction and reducing the flow rate may completely consume the starting material, but limit production efficiency.

The crude product was further purified and analyzed using mass spectroscopy, proton-NMR and fluorine-NMR. It's important to show the reactors are pumps according to the chemical property and absorbability of substances, especially for those who highly or for those reactions with solid formation. Reactions that have a liquid effect and faster reaction rate can be carried out effectivity using a continuous flow system.

In addition, it can cause reaction that may or may not result in the formation of a solid.

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Journal (Chemistry)

Journal (Chemistry)

A Scalable Balz-Schiemann Reaction Protocol in a Continuous Flow Reactor

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