Andreas Kirschning, professor and director of the Institute of Organic Chemistry at the Leibniz University since 2000.

Jens Wigner, third-year PhD student working on natural product synthesis and inductive heating as new enabling technology. Lucas Kuppach, PhD student, my interest develop of multi-step reactions.

Jan Hartwig, currently writing my master thesis in the group of professor Kirschning. Let's talk about flow chemistry. It's a new field of organic chemistry and organic synthesis that has great future prospects

because flow chemistry allows to carry out synthesis with hazardous or explosive materials, for example, like azides that are much more difficult to handle when you carry out that chemistry and the batch conditions.

So today I would like to introduce you to our latest chemistry, our latest synthesis in the field of azides. We will start today with our latest developments on how to make vinyl azides, but the highlight definitely is the second part of our work where we use vinyl azides having prepared under flow conditions

to create heterocycles of possible pharmaceutical or agrochemical interest. And this will be done with technology that is based on inductive heating.

Inductive heating is a very new way of combining enabling technology flow chemistry with a new heating device and I'm very sure that we will see today in this little film how inductive heating can change the way chemists perform synthesis in the laboratory.

Here we have the reaction setup for the synthesis of vinyl azides in a flow system. For example, here's one of our developed polymer bond reagent, the first polymer for the addition of iodoazide.

These polymers are filled into the reactors, the reactors made of glass and the starting materials are pumped through them via this syringe pump. The advantage of polymer bond reagents is that after the reaction in the reactor, no filtration or further workup is needed

and the first reactor can be directly connected to a second one where the elimination takes place. The desired vinyl azide can be directly collected into a round bottom at the end of the system.

For further reaction with the desired vinyl azide, I need to remove some of the items here and show you a second system.

This is the second reaction setup. It's slightly different from the first one. It consists of this HPLC pump, a loop to inject small amounts of starting material, a glass reactor filled with copper and a round button to collect the product. In this third reaction, a copper mediated click chemistry, we need elevated temperatures.

We do not use conventional heating methods to perform the reaction, but instead we are using inductive heating. We have this black box, the inductor, where the reactor can be easily removed and installed again and the AC generator which powers the inductor.

The advantages and some theoretical background is explained by my coworker Jens. Okay, thank you Jan. Now that you have all the information about the chemistry we perform here and you've also seen the technical setup we use here for our flow chemistry,

I would like to tell you something about the inductive heating. So how does it work? What's the physical principle? And why should you use it in combination with flow? So most of you may have already heard something about inductive heating. Either you have it in your kitchen at the heating plate or you have heard about it from industry.

There they use it for melting or sintering of alloys and metals. So but what's the physical principle behind it? What we have here is an AC generator which is connected to an inductor. An inductor is a conductive material, for example, copper coil.

So if you have the AC generator working, you get an induced magnetic field in the inductor. This magnetic field is oscillating and if we then induce a heatable material which is another conductive material into that oscillating magnetic field,

we get an induced current in that material. This current is called eddy current and now we have mainly two effects which generate heat in that conductive material. We have the resistance heating due to the induced current which is the same you have in your light bulbs.

And there's this effect called hysteresis and what we have here is the friction by the magnetic domains in that material which go back and forth due to the oscillating magnetic field.

So now you know how it works. So what is inductive heating? How does it work? But why should you use it? So when you would like to heat up a flask, you have your oil bath, for example, so that will be conventional heating. You have your fluid temperature of your oil, which is here, which is high. Then between the oil and your flask, there's a thermal boundary layer.

In that thermal boundary layer, the temperature decreases. Then in case you go through the wall, the temperature decreases further and inside there's a second thermal boundary layer where the temperature decreases further.

So now the temperature of your fluid which you would like to heat up is much lower than the temperature you set for your oil bath. So what you do now with inductive heating is you have your inductor, as I've shown you. So you have your inductor here outside and encased is your reactor here.

The reactor is filled with the conductive material and as soon as you switch on the inductor, this material is heated up. So we have a fixed bed reactor with our fluid going through. And due to this fixed bed reactor, we have a temperature profile which is horizontal.

That means the temperature inside and outside of the reactor is the same. So that's quite beneficial. I've shown you now the principle of inductive heating and I've shown you the benefits of inductive heating. And now I would like to show you how a reaction with inductive heating is performed practically.

For that, we go back to the fume hood with our technical setup and I will show you the click reaction, the copper catalyzed click reaction and how you set it up. So we have the AC generator you have seen before.

What you do first, you switch it on. Then you switch on the water because it's a water cooled generator. And the two values you can change here in that generator is on the one hand, the frequency and on the other hand, the power input into the material.

So what we have here is we set the frequency to 15 kilohertz, which is the ideal frequency for copper turnings of this size. And then we set the power input to a certain value which correlates to a certain temperature.

But before I start our generator, I would like to show you the temperature in our reactor we have now. As you can see here with our pyrometer, the temperature on the surface of the reactor is round about 22 degrees.

Now I plug in and start our generator. And after only a few seconds, you already see an increasing temperature.

So we're already at 28 degrees after only five seconds. And that's another benefit of inductive heating. So the heating is much more rapid than with conventional batch technology. For example, oil baths and other heating technologies. After you switched on the heating, what you have to do next is prime the whole system with the solvent you want to use.

For that, of course, you switch on the HPLC pump you have seen before. And now we have to wait till the temperature has reached the value we would like to have. But what I can show you is that the radiation we have here is not dangerous at all.

And only this part of the reactor is heated. So what we have here, we can take out the reactor and there's no heat, no dangerous radiation. So when the system now is primed, I can inject or load this sample loop with our reagent mixture.

So I inject it. And as soon as the temperature has reached the value we would like to have, you inject the reagent mixture. And that only takes a few minutes here in this case.

And now we have reached the temperature we would like to have. It's around 70 degrees. That's the temperature we're working at. So you inject the sample and the reaction is running.

Today we presented a new enabling technology being introduced into organic synthetic labs. You've seen that inductive heating can efficiently be combined with flow chemistry, realizing a technology platform that allows safe and very rapid heating in continuous flow conditions.

One has to see and visualize inductive heating in the context of other heating opportunities, such as microwave, which definitely is also efficient, but from our point of view,

lacks safety issues to some extent. In that context we utterly believe that inductive heating has future prospects for organic synthesis in the laboratory scale as shown today.