you probably seen videos before on youtube which involve the extraction of

caffeine from coffee. Caffeine is a xanthate stimulant. Today we're going to extract a

different xanthate stimulant, theobromine, and we're going to be starting with cocoa powder

which contains the small amount of this compound. Here's our starting material. 40 grams of cocoa

powder. This is Dutch processed cocoa which means that it has been treated with alkali.

We're not sure if this makes a difference, but we'll soon find out.

We're going to use a large beaker throughout the extraction process because it's going to

make things a bit more convenient. First let's get our cocoa powder in.

Here we go. The first part of the process is going to precipitate out some acidic

components in the cocoa which would otherwise be impurities in our final product.

To remove these we're first going to add the solvent.

Here's 75%.

We're not sure, but it's likely that phenol could be substituted if you wanted to.

Okay, let's get this into the beaker.

Now we'll stir around to form a homogenous paste.

Looking good. Both delicious and toxic at the same time. Just how we like it.

Next we've weighed out 5 grams of dry magnesium hydroxide powder.

This is going to form a salt with the unwanted components which will then be insoluble in organic

solvents.

Here's 40 mils of water.

We place this into a small beaker.

And then add the magnesium hydroxide.

On stirring this forms a nice white suspension.

We then add this to our cocoa and methanol mixture.

And stir well for a few minutes to form a homogenous paste.

Here we go. Now we've got to evaporate off all of the methanol and water to form a dry solid again.

It's important not to heat too high though, otherwise we'll start to burn.

burn the mixture.

So we put the beaker on a hot plate set to just above 100 degrees.

Pretty soon the methanol starts to boil off.

After about 1 hour we're left with a thick paste like this.

So we prepare a glass dish and pour the semi-solid cocoa mixture into this.

Then we bake in an oven at 100 degrees C for a few hours, occasionally breaking up any

lumps of solid, until we're left with a dry powder again.

For the next step we're going to use the same beaker as before, which we didn't wash.

Now we need to extract the remaining non-polar organic components out of the cocoa powder,

so to do this we're going to use 150 ml of dichlor.

We've put a large stir bar in the beaker, and now let's add the solvent.

We've got the solvent stirring vigorously, and we're now going to add the dry cocoa powder

mixture.

The original procedure now calls for this mixture to be reflux for an extended period,

so we're going to use the soft sachelet extractor.

Instead we're going to cover this up and leave it stirring vigorously for 2 hours to see if

this extracts enough to isolate some product.

Here we are 2 hours later.

The powder has mixed into the solvent creating quite a thick paste.

Now we set up for vacuum filtration in order to separate the solids from the solvent, which

now hopefully contains our product.

The DCM coming through appears slightly oily and seems to leave a residue on the glassware.

This must be due to oils and fats dissolved out of the cocoa.

We use the further 25 ml of dichloromethane to wash out the beaker and then wash the solids

remaining in the filter funnel.

Here's our filtrate.

A slightly orange color.

Some of the DCM has evaporated off during the vacuum filtration process, but this is

OK.

Now we're going to use some anhydrous magnesium sulfate to dry the DCM solution.

It takes a few grams to do this properly.

The mixture then settles and there's a nice transparent orange colored liquid.

Now we're going to evaporate off most of the DCM.

So to do this we've prepared a 250 ml flask.

And we decant in the solvent solution.

If you like, you can set up for distillation and recycle the DCM.

We're just going to boil it off.

But if you do this be sure to use good ventilation as the DCM solvent vapor is toxic.

With gentle heating the DCM soon starts to boil off.

And here we are.

We want to get down to about 10 ml of liquid remaining, so keep going with the evaporation

of the solvent.

Here we go.

Just a small amount of a cloudy looking mixture present in the bottom of the flask.

Next we've measured out 35 ml of diethyl ether.

This is as called for by the procedure.

But we're not sure if it can be substituted.

We add this to the chilled residual dichloromethane mixture.

And almost immediately there's a milky color formed in the mixture.

And a very fine white precipitate settles to the bottom.

We chilled this mixture for an hour in order to precipitate out all of the solid product.

Then we set up for filtration.

We're using dull grade for pouring.

We're using a

porosity glass center because the precipitate is quite fine and we want to make sure we

capture it properly.

We left the solid dry thoroughly on the pump.

And now we're going to put the solid back in the flask.

Here's what we ended up with.

170 milligrams of crude theobromine powder.

It's a very fine off white solid.

We could resist and did a taste test using a toothpick.

It has a strange bitter taste and slightly numbing sensation on the tongue which is very

reminiscent of powdered demerol.

This is a lower yield than we expected, but probably due to the inefficiency of our extraction

process.

If you want a better and more quantitative yield then you'll need to reflux the cocoa

and dichloromethane for a period of time.

Theobromine is apparently similar to caffeine but without as strong a cardiovascular component

to the stimulant properties.

Thanks for watching and stay tuned for more videos.

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