no this isn't another present from our cousin in France she's got something

planned but won't tell us what though this is a lot more OTC ibuprofen

tablets today we're going to extract and purify ibuprofen from these and also

look at the molecule in some more detail because it's quite interesting we'll

also show you how tablet extractions can go wrong let's have a quick look at the

molecule a few interesting features it's a

propionic acid derivative but you can also see a phenyl acetic acid backbone

in there as well there's a paw rod substituted tertiary butyl group on the

ring and there's also two optical isomer possible but we'll come on to that later

okay let's weigh the tablets we've got 40 tablets here each containing 400

milligrams of ibuprofen so that's 16 grams in total

but the total tablet weight is 25 grams so that's 9 grams or 36% by way of

fillers and binders and other things technically these are known as crap and

we will need to remove them okay first step is our standard

operating procedure

getting there will bash it a bit more so it's a bit finer okay here we go we're

going to try out two different extraction processes firstly we're going

to see if we can get the ibuprofen to react with sodium hydroxide forming what

should hopefully be water-soluble sodium salt then secondly we're going to try an

organic solvent extraction process

so we'd split the crushed tablets into two batches

each containing 12.5 grams of powder let's deal with the first

you remember from the structure ibuprofen is a carboxylic acid and in this

acid form it's virtually insoluble in water

but we'll see if it can dissolve in sodium hydroxide solution to form a

soluble salt

here's three grams of sodium hydroxide which should be about twice as much as

we did here which is Нет garlic来一下

We need in theory to react.

And here's 50 mils of cold water.

First we'll make up the sodium hydroxide solution.

Okay here we go.

So let's add the crushed tablets.

And stir it up.

Here's our first sign of trouble.

The solids aren't easily dissolving.

In fact, it actually looks as though the mixture is starting to thicken.

Tablets often contain cellulose derivatives.

Such as hydroxyl.

Methyl cellulose.

In contact with water these compounds can form thick gels.

Similar to the ones you get if you mix corn flour and water together.

We left this mixture to stand for a little while and it became thicker over time.

Here we are 15 minutes later.

It looks like a paste.

This is not filterable or extractable using another solvent.

It's a very intractable mess.

We added some hydrochloric acid to the mixture to see if this would reverse the process.

But it didn't.

In fact we now successfully synthesized ibuprofen cottage cheese.

Yum yum.

So this method is a dead end.

A nice idea in theory but you'll find this with a lot of tablets.

Water should be your last resort in terms of extracting.

Unless they're really pure and without much crack in them.

Okay so let's try something different with the other 12.5 gram batch of our crushed tablets.

Ibuprofen is highly soluble in chloroform, DCM, acetone, and a few other organic solvents.

Ethanol not so much though.

So let's try acetone.

Here's 40 mils of dry acetone.

And hopefully this will be able to dissolve.

Dissolve out the ibuprofen without swelling up the cellulose tablet binders into a gel.

We'll give this a good stir for a few minutes.

Looks like we've got a lot of the solid dissolving very rapidly.

So we set up to filter.

We wash the beaker and solids carefully with about another 20 mils of acetone.

Here's our acetone filtrate containing our ibuprofen.

And here's what was left over in the filter.

A white strangely textured solid.

The acetone was very efficient at extracting the ibuprofen so there's nothing left in here.

Okay we're now just going to take the acetone filtrate and pour it into the filter.

And use a hot plate to evaporate down the solvent.

While we're doing that, let's take another look at the ibuprofen molecule because there's

an interesting feature that we haven't explained in any previous video.

This is the concept of what's known as optical isomers.

Some molecules can exist in two forms which are mirror images of each other.

Like you have two hands.

Left and right.

And this happens in a molecule where you have two hands.

Or you have a carbon atom connected to four different groups.

So look at the examples on the screen.

Only in one of these do we have a carbon which has four different things attached to it.

So let's look again at ibuprofen.

Can you spot a carbon atom which has four different groups attached?

Well there is one.

And it's here.

And let's draw out the two mirror images so you can see that it's just like your two hands.

There's a left-handed version and a right-handed version.

Now most of the time you don't notice this.

In fact the physical properties such as melting point and solubility of these two compounds

are identical.

And when they interact and react with any simple molecules which don't have mirror images,

the behavior can be different.

But there is an exception.

When these compounds react with other molecules which have mirror images,

the behavior can be different.

Just like if you try to shake hands with someone using both your right hands together,

it feels weird.

The terminology used sounds a bit strange.

A carbon with four different groups attached is called a chiral center.

And the two versions of the molecule are known as optical ions.

Or also as enantiomers.

Inside the human body,

the amino acids that make up your proteins mostly exist as just one of these mirror image forms.

And this is why when it comes to drugs,

there is often a big difference in activity between the left and right-handed forms.

Sometimes you can even get drugs or molecules which have multiple chiral centers.

And then it becomes even more specific.

Check out Ramadol for a good example.

But just remember that unless they are interacting with something else which has mirror image forms,

the chemical properties are the same.

Okay, well we're left with a slightly viscous liquid in the bottom of the beaker.

And so we allow this to cool.

Crystallization is quite slow so we'll add a bit of ice to see if this helps it along.

It's happening but slowly.

So what we're going to do now is not crystallize this completely,

but instead we're going to re-dissolve the crude ibuprofen we've got here in sodium hydroxide solution

to form the sodium salt.

Here's 3 grams of sodium hydroxide,

and we'll dissolve this in 40 ml of water to form a clear solution.

As you can see,

the ibuprofen is starting to crystallize.

So let's add the sodium hydroxide solution to the oily ibuprofen.

The result is really very pretty.

So watch and enjoy for a minute.

And finally we've got the clear solution.

And interestingly this soon crystallizes itself into a quite thick mass of crystals of the sodium salt of ibuprofen.

A quick blast of heat though and it re-dissolves.

So it must have quite a sharp solubility curve in water.

Okay so now we'll add some concentrated hydrochloric acid to the solution

and this should precipitate out the ibuprofen,

leaving any water-soluble impurities behind in solution.

Here's 10 ml of acid.

Here's 10 ml of acid.

Here's 10 ml of acid.

The ibuprofen has separated again as an oily liquid on the surface.

With a bit of cooling this soon crystallizes.

So we break up the solid and then filter off our product.

We wash very thoroughly with water and then dry the product.

It takes a while to dry.

And here we go.

Our dried final product which is pure ibuprofen weighing 7.5 grams.

This is a 94% recovery on the material in the starting tablet batch we used.

So a little bit of mechanical loss but not much.

We've got some very cool ideas of what we can do with this.

But we need to do some rigging up and get our safety procedures down pat before we do.

So stay tuned.

Okay one final note on ibuprofen extraction.

You may also come across non-generic tablets which are colored and maybe look like this.

Normally the coloring is on the outside only.

And the center of the tablet contains a composition very similar to the one we just covered in the video.

The catch though is that you really need to get rid of this outer coating before you try to do any organic extraction.

Otherwise it really messes things up.

You can do it by hand.

But it's a bit painful.

We also found that soaking the tablets in a small amount of absolute ethanol worked at loosening up the outer layer.

Which then fell off quite easily without dissolving too much of the product.

So now we've got another interesting carboxylic acid.

To play with.

Thanks for watching and stay tuned.