So what a surprise! Back again, Nile Red is doing a caffeine extraction.
This time though, the recovery should be a lot better because we're not targeting
it in a natural source. Today we're going to be trying to target our caffeine in caffeine pills.
This process should be a little bit cleaner than from a natural source and
in the end we should have a nice pile of caffeine powder. Also, just as a final
installment to my caffeine obsession,
I do plan to synthesize it from scratch in the future.
OK, so let's get started.
For this extraction, I opted to use a hundred pills containing about a 100mg of caffeine each.
Remember that different brands use different ingredients so your procedure
might differ a little bit if you use a different brand.
Besides the caffeine pills were also going to need an organic solvent and in
my case I use dichloromethane.
I started by opening the bottle and pouring the pills out into a beaker.
This step is pretty redundant and I did it just so you can see how many pills
we're working with.
Anyway, what we want to do is you want to crush these pills up to a powder.
So I add them to a mortar and I make sure not to add too many at a time because
this can make it hard to crush them up.
So I keep crushing the pills until I get a reasonably fine powder.
When I'm decently satisfied, I poured the pills into an Erlenmeyer flask and
I moved on to crushing more pills.
So I add more and I repeat until all of the pills are crushed.
If you're lazy you can optionally just use a coffee grinder for this step.
Unfortunately I didn't have a coffee grinder so I had to struggle through
this using only my weak chemist arms.
The final amount of pill powder was transferred to the Erlenmeyer and now
we're ready to move on from this very tiring step.
So before proceeding on, we drop in my trusty stir bar so I don't have to stir
anything manually. Directly onto the powder, I then pour in 120mL of dichloromethane.
According to the ingredients of the caffeine pills, everything should be insoluble
in DCM except for caffeine and one other thing called povidone.
This is okay though because we'll deal with the povidone later.
The funnel is removed and a watch glass is placed on top to limit the
evaporation of the DCM.
I let this stir for an hour and then I turned off the stirring to let the solid
sink to the bottom.
It's really important to wait long enough that the solid solidify at the bottom,
otherwise the filtration step is going to be next to impossible.
I then pour the murky liquid portion into a fritted filter.
I attach my vacuum pump and I separate the liquid from the solids.
You can see that the filter caught quite a lot of the solids but the filtrate is still pretty murky.
To the solids at the bottom of the flask, we add further 15mL of
dichloromethane and we do the exact same thing and we let it stir for about an hour.
After the hour we let the solids collect on the bottom and then we filter.
So just like before we add it to the filter flask and using vacuum we pull it through.
Then, just to clean up things a little bit, I wash the sides of the filter
flask using a little bit of dichloromethane.
This is what was filtered through but you can see that there's still quite a
bit of solid in there.
So to try to separate some more of the solids out, we filter it again.
This step is pretty optional because I don't think that the filter actually
caught too much of the solid.
What we have to do now is remove the dichloromethane solvent and we do this by distillation.
When all the DCM is gone, we're left with some pinkish white powder at the bottom.
Using a metal spatula, I break it up into pieces.
When the pieces were small enough, I poured them out of the round bottom
flask and into a beaker.
Once they're in the beaker, I broke them up more into a nice coarse powder.
At this point is pretty easy to tell that the caffeine isn't pure because of the
vast amount of random pink stuff.
To get rid of this stuff, we carry out a recrystallization.
For the recrystallization, we dissolve the caffeine in a minimal amount of hot water.
When we cool it down, the solubility of the caffeine should drop and it should
crystallize out of solution but the impurity should remain quite soluble and
stay in solution.
This way we can filter off the liquid and we should be left with reasonably
pure caffeine crystals.
I keep adding hot water until the solution more or less clears up and then
I take it off the hot plate and let it cool to room temperature.
Once at the room temperature, we can put it in the freezer to crystallize out
as much caffeine as possible.
After taking it out of the freezer, we're left with something that looks almost
exactly like cotton candy.
I then added the cotton candy like caffeine to a Buchner funnel.
When I pull the vacuum, you can see it deflates a little and some of the pink
color disappears.
I turned off the vacuum and added some cold water.
I mix it around using a spatula to try to wash it a little.
I then pull the vacuum again and you can see here that the caffeine is
looking more white than before.
I then repeat this washing step one last time just to get the caffeine as
pure as possible.
I let the vacuum on a little bit longer to dry the caffeine and we're
left with some nice white caffeine at the end.
I transfer the nice white fluffy caffeine to a small crystallizing dish.
To get rid of the water that's still present, I place it into an oven and heated it at a very low heat.
When it was taken out of the oven, it was pretty dry and I was able to crush it up
into a nice fine powder.
Instead of recrystallization, the other option of purification is sublimation.
Caffeine is one of the special molecules that doesn't really have a liquid phase
and instead when you heat it jumps directly from the solid to the gas phase.
By placing it on a very hot hot plate,
we can sublimate the caffeine and allow the crystals to form on the side of the
beaker and the bottom of the round bottom flask.
On top of the beaker is placed a round bottom flask that's filled with cold
water to try to limit the amount of caffeine that escapes.
When we feel like enough caffeine has sublimated and collected on the walls
and the sides, we can take it off the hot plate and let it cool.
It's really important not to remove the round bottom flask while the beaker is still hot.
When the beakers turned upside down some, very nice white powdered caffeine falls out.
This is a pretty efficient method of purifying caffeine and most of the
impurities simply just burn or char on the bottom of the beaker and stay there.
You can see here the final nice white caffeine powder that we got.
The amount that I was able to recover was about 8.5g which
is pretty close to the theoretical 10.
Again, here's a list of the videos that I'm currently editing and future videos I plan to film.
In the "Videos being edited" category, you can vote for the one that you want me to publish next
and in the "Future videos" category you can vote for the one that you want me to film next.
Also, if you're feeling generous, please donate to my Patreon account because
with a bigger budget per video, I can do more things.
Also, just as some added information to this generic outro,
I've actually gone ahead and made a YouTube fan page.
When I get my act together I should be able to set up polls there where people
can vote on the next video.
Anyway, that's all for now and I'll see you on the next one.