In this video we'll prepare pyridine and oxide.

Unlike benzene or toluene, pyridine itself is extremely unreactive towards .

electrophiles. By making the N-oxide we're hoping that this will be more .

reactive and allow us to explore the chemistry of pyridines a bit easier.

This is our third attempt at this reaction and we've been playing with .

conditions and the setup a bit because we couldn't get much out of the .

literature. We've set up a 250 ml flask with stirrin and this is sat in .

an oil bath. We've got the thermometer in the oil bath. So now for our main .

reactant. This is 20 grams of liquid pyridine. It doesn't seem to matter if .

it's not completely dry, but we're using reagent grade here. Place the pyridine .

into the flask .

and heat the flask.

Now pour the flask on the oil bath until the temperature in the oil bath is .

between 90 and 95 degrees C.

Now for our oxidizing agent. Literature references suggest using .

paracetic acid for this reaction, but given that this is dangerous and .

explosive, we're going to use our baryohydrogen peroxide duct that we .

prepared in a previous video. We've weighed out 24 grams, which is a .

stoichromatic amount to the pyridine.

in order to see how this works the paradigm is heating up and we've added .

the thermometer into the flask as well so we can record the temperature of the .

liquid inside directly as well wait a few minutes and allow the temperature in .

the flask and the water bath to equalize above 90 degrees C this is one of those .

reactions where the temperature has to be over a certain amount to react but .

temperature can result in an out-of-control reaction so you need to .

be careful so now we start to slowly add a small amount of baryoproxide the duct .

to the flask .

as the solid hits the hot liquid it seems to melt and dissolve and starts to .

fit with some decomposition at first the fizzing quickly dies down .

you .

and it seems as though the addition of the solid cools the mixture slightly so .

wait a few minutes for temperature to rise again .

and then at some more of the solid that's some point about a quarter of the .

way through addition we notice that the fizzing continues when the solid is .

added and at some point this seems to trigger off the reaction in the liquid .

the temperature starts to rise at this point you see a little bit of pyridine .

refluxing it's not hot enough to boil but the high vapor pressure is enough to .

cause this watch the temperature closely if it goes over 100 degrees C then we .

found that simply removing the flask from the oil bath and leaving the minute .

caused the temperature to start to drop again .

you notice a yellow color forming in the mixture he pond an ingredient rock .

side and try to keep this reaction going but without allowing the temperature to .

rise uncontrollably if it does rise to high then at around 115 degrees the .

pyridine will boil towards the end of addition the reaction is really in .

underway how much of this is simply the hydrogen peroxide decomposing however .

we're not sure we'll find out now we've finished addition we left the flask .

stirring in the oil bath for an hour during this time the fizzing dies down .

substantially and then we allowed the mixture to cool to room temperature it's .

now at about 40 degrees C and the color has changed to a dark orange so we .

chilled down to zero degrees C in the freezer .

and as you can see we've got a large amount of crystalline solid forming and .

we filtered this off we count fine much on the solubility of our product except .

that it's extremely polar and hence very water soluble we suspect that the .

crystals are still in the water and the crystals are still in the water and the .

crystals here are in fact urea as a side product of the reaction so we measured .

out 20 mils of di-fluoromethane .

and washed the crystals in the flask with this hoping that the product would .

be somewhat soluble in it with urea not being .

so here are the needle-like crystals 10 grams of an unknown substance which .

now it's just over 100 degrees C we strongly suspect that this is urea as a .

byproduct of the reaction .

we placed a small amount in a beaker and then added a drop of a suspension of .

manganese dioxide in water so it's definitely not our starting period the .

rockside compound .

the filtrate contained two layers one apparently aqueous and one dichloromethane .

this also has a strong aroma of unreacted pyridine we figured we'd boil .

and evaporate this down to see what was in it, but first we did a safety check.

We placed a small amount of the liquid on some starch iodide paper.

No dark blue color means no peroxide.

So we're safe to boil this down.

We boiled down the mixture using strong ventilation in order to avoid dichloromethane and pyridine .

fumes.

Eventually the temperature rose to 130 degrees C and only a liquid remained with no further .

boiling.

We poured this into a small beaker.

And soon it started to solidify.

This is a good sign because the literature value for the melting point of pyridine n .

oxide is 65 degrees C.

Thanks for watching.

Here's our crude product.

8.5 grams of a brown colored amorphous waxy solid.

On exposure to air it seems to slowly absorb moisture and becomes a water solution.

It's not pure but from its properties we're confident this contains a lot of pyridine .

n oxide and with a maximum yield of 35%.

We did a few tests to establish its solubility.

It is extremely soluble in water.

And a pyridine n oxide.

It appears to be not at all soluble in toluene.

Very slightly soluble in dichloromethane.

And slightly soluble in ethanol.

It is very slightly soluble in acetone.

But acetone was the only solvent we found which removed some of the yellow color, leaving .

the solid.

So we used cold acetone to macerate the solid and crush up the lumps.

And then we filtered this and quickly dried on the pump.

See you next time.

This gave us a tan colored powder.

We'll experiment and use this directly in a follow up reaction to see if this works .

okay as it is.

So our conclusions from this reaction.

Urea peroxide works as an oxidizing agent but a lot of it decomposes in the process .

and so a large excess is required.

We think probably 2 to 2.5 molar excess.

Due to the polarity of the product, it's hard to separate it from inorganic salts, .

and it's hard to get the orange color out.

It's also hygroscopic so you need to handle it carefully or it will just form a puddle.

Stay tuned and see if we manage to use our pyridine endoxide in a follow up reaction.

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