Today we're going to have a go at oxidizing the cyclone hexanone we made in a previous

video to adipic acid a six carbon double carboxylic acid we're going to use potassium permanganate as

the oxidizing agent first we wanted to check out just how exothermic this reaction could be given

that permanganate can be a very powerful oxidizing agent here's some potassium permanganate and a few

drops of meat cyclone hexanone the good news is that it's not hyperbolic

there is no spontaneous ignition let's give it a helping hand

we're going to have to tame this oxidation process and do it with some care so

here's our set up we're using the 500 ml flasks and we've got stirred bar and

thermometer in there

We can carefully monitor the temperature.

We're going to use 150 ml of water as a solvent to perform the reaction in.

Since our product is slightly soluble in water we have a difficult choice.

Too much water and our yields will be low.Too little and we could have a runaway reaction.

Let's get the water into the reaction flask.

We're using slightly warm water at 40 degrees because we want any reaction to kick off quickly

so we know where we stand with it.

Now for our oxidizing agent.

Here's 32 grams of potassium permanganate crystals.

This is a 2 molar ratio with the cyclohexanone we'll be using.

Here's our reaction flask stirring away.

Now we'll add the permanganate crystals to the water.

Not all of them will dissolve at this temperature, but that's okay.

Once they're all added, we measure out 0.5 grams of solid sodium hydroxide.

And we're going to make a solution using 5 ml of water.

The permangoni isn't going to react with the actual ketone group of our cyclohexanone.

Instead it's going to react with the double bond present in the phenol form of the ketone.

By adding a little alkali and raising the pH of the reaction mixture, we increase the

amount of phenol form and so hopefully catalyze the reaction a bit.

So we've added our sodium hydroxide solution and now we're ready.

Here's our cyclohexanone.

We've weighed out 10 grams into a small beaker.

Check out our previous video for more details of how we made this starting from cyclohexanol.

We're going to start off slow, so we're going to use a dropper to add the cyclohexanone

to the reaction mixture.

We're starting with about 3 quarters of a ml.

With stirring on vigorously we're just going to watch the temperature and see if we can

see a reaction.

It's starting to look like a real reaction.

It takes a few minutes, but we start to see a slow but steady increase.

There's slight brown tint appearing in the reaction mixture as well.

The reaction is slow, but it's pretty relentless.

After about 6 or 7 minutes the temperature had steadily climbed and was about 60 degrees

C.

So at this point we decided to apply some cooling to the flask.

We started with an ice pack.

We're going to add our sodium hydroxide solution.

But this didn't seem to have much of an effect.

So we used a bowl of ice water.

And at this point the reaction seemed to be finished.

And the temperature slowly came back down again.

So we added about another ml of the cyclohexanone to the reaction mixture.

This time we kept the flask in the cooling water.

Cool.

Cool.

Cool.

and after a few minutes the temperature started to rise again the second and

subsequent additions weren't as vigorous as the first and we managed to add all

of the cyclohexanone to the reaction mixture in four batches over about 40

minutes here's the reaction mixture at the end we allowed to stir for another

hour as it cooled down slowly to room temperature we added a drop of the

reaction mixture to a beaker containing water

no purple permanganate color so it looks like this shows over

here's the cooled reaction mixture lots of brown suspended manganese dioxide in

it.

so we set up for filtration to get rid of this

we've got a clear filtrate but it's a slightly red color we're pretty sure

this is due to a dirty filter as a consequence of our previous henry

reaction video the red color is very difficult to get rid of

to clean the flask and anything else that has come into contact with the

brown reaction mixture we prepared a strong solution of sodium bisulfite in

water the flask is a bit of a mess as you can see

but the bisulfite solution reduces the brown manganese dioxide and makes cleaning it much easier

and makes cleaning it much easier

left in the filter is a brown precipitate of manganese dioxide save this because you

can't turn it into active manganese dioxide which is a useful oxidizing agent

here's our filtrate yours should hopefully be nice and colorless if you

used a clear filter along with decomposition products and products of

side reactions this hopefully contains our added pick acid in the form of the sodium bicarbonate.

and potassium salt we're now going to add concentrated hydrochloric acid to this

in order to generate the acid there's a little effervescence which we assume is

because one of the oxidation byproducts would have been carbon dioxide which

would have been reacted with the alkali present to form a carbonate salt on

adding the acid the red color turns yellow

indicating that it is an impurity from the filter from our previous reaction

we've added about 10 mils of acid so let's test the pH strongly acidic so we'll assume at this

point that all our added pick acid is present in the solution is the free acid since the acid

is soluble in warm water but not very soluble in cold water we're going to

chill the mixture down now and see if our product crystallizes out after an

hour of chilling here we are there's a white crystalline precipitate in the

bottom of the beaker

so we set up for filtration again

we wash the product with a little ice water and then dried it thoroughly on

the pump

and here's our dry product 3.5 grams of Addie pick acid this is only a 24%

yield on the starting cyclone hexa known so it's possible that we haven't quite

got the reaction conditions right for the stoykyamotoxin

correct in addition some of the product will have stayed dissolved in the liquid

due to its solubility but it's nice and crystalline and seems

quite pure if you're going to try this reaction then be careful because even

though the reaction is slow it's difficult to control even with cooling

go very slowly and take extra care if you scale up

stay tuned to see what we've got planned for our adipic acid