We've had a viewer request to perform an oxidation of an alcohol using acid and dichronate, known as Jones' reagent.

So here goes.

The reaction works in the 3 to 1 to 8 ratio technically, but we're going to use slightly more dichronate and acid to make sure it goes to completion.

We first weighed out 55 grams of solid potassium dichronate.

We placed 200 mils of water into a large beaker and equipped with a large magnetic stir bar.

Let's get this stirring.

And now we add the potassium dichronate.

It won't all dissolve yet.

We set out the thermometer to track the temperature.

Now for our acid.

This is 80 mils of concentrated sulfuric acid, or an 8-mol equivalent compared to the dichronate we used.

We're assuming 1 mol of acid will donate 1 hydrogen ion.

We start adding the acid to the dichronate solution slowly.

See the color changing red.

A lot of heat is generated.

The temperature of the mixture at the end of addition is 90 degrees C.

Here's our hot Jones' reagent.

Notice that all of the dichronate has now dissolved.

This solution now contains chromic acid.

We cover this up and allow it to cool down to about 50 degrees C before we begin the next step.

Okay, setting up for the reaction.

We're going to use a large 1 liter flask.

It's advisable to get away with a smaller one depending on how you are going to extract the product.

We've got a large magnetic stirrer and a thermometer in here so we can record the liquid temperature.

This is important.

Since we're doing some old school chemistry, we're using our nice old school addition funnel.

And the ground glass doesn't hurt when you're dealing with hot chromic acid.

Here's our alcohol.

50 grams of cyclohexanol.

This is 3 molar equivalents compared to the dichronate.

Cyclohexanol sounds exotic but it's an industrial bulk chemical due to its use in the manufacture of nylon.

So hunt around and you may be able to find it.

We've got a funnel set up to easily add this to the flask.

It's slimy.

Slightly viscous, gloopy liquid as you can see.

Now we've washed the beaker with 100 mils of water.

And we're going to add this to the flask as well.

As you can see the alcohol isn't mixable with water.

But on stirring it forms a milky emulsion.

Okay, we got the alcohol ready and stirring.

Now double check that the tap on the addition funnel is closed.

And we add our chromic acid Jones reagent solution.

It's still slightly warm but this is okay.

And now everything is ready.

We're going to allow the pressure to equalize by leaving one of the necks on the flask open.

So let's start the addition.

To start we'll add about a 10 mil portion of acid and see how this goes.

After a few minutes the reaction mixture starts to turn a dirty brown color.

And we watch the temperature to make sure it didn't increase too quickly.

The reaction is starting to get underway and we can see the temperature slowly rising.

But it's all under control.

We added another portion of acid mixture.

And as it reacted the temperature in the flask rose to just over 50 degrees C.

At this point we set out the slow steady drop of acid into the flask.

The temperature around 60 degrees C.

But without getting higher.

And we left the reaction going like this for a few hours in order for all the acid to add.

If you want to speed things up you can by using cooling via an ice pack or in a water bath.

Just don't let the temperature rise about 65 degrees C.

About halfway there now.

So we've completed addition.

The reaction mixture looks like this.

A very deep dark blue color.

We decided to neutralize excess dichromate in the reaction mixture using some solid oxalic acid.

You could use isopropanol instead.

You could also skip this step but we recommend it to get a good pure product.

We added about 10 grams in total.

Now straight away.

Before the mixture cools.

Set up for simple distillation in the same flask.

What we're going to do is steam distill the product.

If you are using a different alcohol which won't steam distill or form an acetate rose.

You could also extract it from the reaction mixture using an organic solvent.

In our case the product is actually an acetate.

It's not immiscible with the reaction mixture.

But we're going to steam distill as it gives a nice pure product.

Get the reaction mixture boiling vigorously.

And pretty soon an azeotropic mixture of water and the product will start to condense.

You can see the two layers here in the receiving flask.

The top layer is our product.

We let this distill for about an hour and a half.

Once we've collected about 150 ml of distillate.

We poured this into a separate beaker and then continued with the distillation.

After a further 50 ml of soda liquid had collected.

We noticed there was no further top layer coming off in the distillate.

So we stopped heating at this point.

We combined the distillates and then poured them into a separating funnel.

We're going to saturate the aqueous layer with salt in order to try to remove as much product as possible that might be dissolved in it.

We gave this a good shake to dissolve.

And then added some more salt.

And shook again.

Once saturated we left the mixture for 20 minutes so that the layers separated fully.

Then we drained off the bottom aqueous layer.

The product did form a slight bubbly emulsion with the final bit of water.

But some shaking and tapping the funnel fixed this.

We drained off the top layer of product into a flask.

Note that the aqueous layer looks as though it's got a small amount of product in it.

If you wanted to you could extract this using an organic solvent.

It would definitely better yield.

Here's our organic top layer, separated off.

We dried this using a couple of spatulas of anhydrous magnesium sulfate.

And then after 10 minutes of drying, decanted into a storage bottle.

Here's the product.

42 grams of cyclothexanone as a clear colorless liquid which is not as viscous as the starting alcohol as you can see.

This is an 86% yield on the starting alcohol.

Which we think is great given that we used no organic extractions or solvents at all in the process.

Its aroma is not as pungent and rubbery as the alcohol.

And is more menthol like.

Let's do a quick check to make sure we've got a ketone.

Here's a saturated solution of sodium bisulfite.

Let's add a bit of our product.

You can see the surface starting to crystallize.

It's quite solid.

Formation of a crystalline solid bisulfite adduct is a classic sign of an aldehyde or ketone.

So that's it.

If you want to do the reaction on a different secondary alcohol.

Get some information about the product's boiling point.

Solubility in water.

And whether it forms an azeotrope.

And choose your work up accordingly.

Stay tuned because we've got some fun ideas for our cyclothexanone.