You will recall that in the previous video we produced chelotonic acid, the heterocyclic
compound. We're now going to use this to create chelodamic acid, the same compound but with
the oxygen replaced by nitrogen. We're starting with 8 grams of the brown chelotonic acid
powder from the previous reaction. See the link shown here for more details on how we
made this. The procedures we looked at utilize a quiosamonia solution, but instead we're
going to use ammonium bicarbonate.
And fairly commonly available baking additive. This will generate free ammonia in solution
and when heated. We're using 14 grams here.
Here's 50 mils of slightly warm water. And we first use this to dissolve the ammonium
bicarbonate to form a solution. Even at a low temperature you can already see some decomposition
into ammonia.
Now we're going to add the ammonia and carbon dioxide gas. Set up a 250 ml flask equipped
with magnetic stirrin. And add the ammonium bicarbonate solution. Now get the mixture
stirring vigorously. And slowly begin to add the chelotonic acid. On addition, you'll need
to see effervescence as the acid reacts with the bicarbonate. So go slowly here otherwise
you'll end up with a foaming mess.
On complete addition you'll have the mixture like this. A darker brown color. But with
some solids still undissolved. We added about another 10 mils of water to the mixture. And
then gently heated the mixture.
To finish the chopper we're adding about 10 ml of water. And then gently heated the mixture.
At first some foaming occurred but this time I'm going to add a little bit of water to
gas was under control, and later this disappeared.
We heated up to 90 degrees C, at which point all the solid had dissolved, and only a small
amount of ammonia gas was being produced, with most being held in solution.
We kept this stirring at heating at 90 degrees going for the next 4 hours.
A lightly inserted Teflon stopper was sufficient to stop the solution from evaporating, but
allowing carbon dioxide to escape.
Every 30 minutes or so we added a little more ammonium bicarbonate in order to ensure the
ammonia concentration was kept up.
This produced some foam which quickly died down.
Now we're ready to go.
After 4 hours, the mixture looked like this.
No more foaming and a deep dark color.
We transferred the mixture into a 200 ml beaker and then heated it in order to boil off some
of the ammonia and reduce the volume a bit.
We were careful not to exceed 95 degrees C during this process to avoid the risk of decarboxylating
our product.
After about an hour we reduced by a third, so at this point we switched off the heat
and then chilled the mixture down to about 5 degrees C.
Here we are.
There's no precipitate as yet and everything is still in solution.
Next we prepared some concentrated hydrochloric acid.
You can see that the fumes together with the residual ammonia are creating a nice mist in
the air.
We added the hydrochloric acid drop-wise.
Almost immediately a yellow to brown colored precipitate was formed.
It only took around 6 or 7 ml of acid to precipitate everything.
So next we set up for vacuum filtration using a glass sinter.
And that's it.
The filter was quite a pale color compared to the color of the reaction mixture as you
can see here.
We broke up the solid in the filter, washed with a small amount of cold water, and then
dried it thoroughly on the pump.
Here's what we got.
4.5 grams of acid.
We're assuming that this is chelodamic acid because the solubility characteristics seem
to be different to the starting material, and it came off exactly as the procedure said.
If so, then we'll assume this is the monohydrate in which case our yield is 57% from the starting
chelodonic acid.
We don't know any specific tests for this, but we'll research as it seems possible that
it might form.
There are some metal complexes that we could use to positively identify it.
Thanks for watching and stay tuned.