Today we're going to be extracting some Aspirin from pills.
Aspirin is the well known brand name, but the common chemical name is Acetylsalicylic Acid, or ASA for short.
Extracting the active ingredient from pills can be a fun exercise on it's own, but I actually plan to use the ASA in a pretty lengthy synthesis.
My goal is to convert Aspirin to Tylenol, following this pathway.
This particular pathway (or conversion) is possible because Aspirin and Tylenol both have phenol as a common precursor.
The plan is to sequentially degrade the Aspirin back down to phenol, and from there it will be built up to make Tylenol.
Each step in this conversion is going to have it's own video, so this series should be about six videos long.
I'm really interested to see what my final yield is, and how efficient this whole process will be.
Based on absolutely nothing, I'll just throw out a random prediction, and I'll say that the yield will be, let's say, thirty three percent (33%).
I'm probably going to be way off, but whatever, we'll see how close I am.
One quick thing to point out before we start, is that throughout the video I'll alternate between using ASA and acetylsalicylic acid.
I just wanted to say that now to prevent any confusion that might happen.
For this extraction, we only need two main supplies. Acetone and Aspirin.
The Aspirin that I'm using here is brand-name, but any source of Aspirin should be fine.
You'll actually see later on in the video that it's not ideal to use brand-name Aspirin, because they include dyes that can be a little bit hard to get rid of.
I've extracted Aspirin in the past, but this time I'm doing it a little bit differently, and I'm using Chem Player's video as a reference.
If you're interested in seeing what Chem Player's video was like, I'll provide a link to it in the description.
To start things off, we need to crush the Aspirin tablets.
The last time I did this, I used a mortar and pestle, but it's a lot easier to use a coffee grinder.
I keep the grinder going for a few seconds, just to make sure that everything has been fully [powdered].
I remove the lid and when I go to pour it into the beaker, I made a mistake.
Let's just pretend that didn't [happen], and I can rewind things and try it over.
This time I'm a little bit more careful and I don't spill anything.
I then go ahead and crush up the rest of the pills and I combine the powder in the beaker.
I forgot to show it here, but I also dropped in a stir bar.
I then poured in two hundred milliliters of acetone (IUPAC: Propan-2-one).
Using a glass stir rod, I mixed the powder around until the stir bar was liberated.
Once the powder seemed adequately mixed with the acetone, I turned on the hot plate.
The goal here is to heat the acetone to it's boiling point, and this doesn't really take very long.
The hot plate I'm using is pretty powerful, so it took less than five minutes (5 min) to get a good boil going.
The next thing we need to do is carry out a filtration to separate the acetone from the undissolved stuff.
I filtered it immediately after taking it off the hot plate, but I think the best thing to do is to let the solids settle out a little bit.
I didn't let the solids settle out at all, so I kind of ran into a problem.
When doing a hot filtration, most of the time you want to do a gravity filtration because using a vacuum can cause some problems.
If I were smart and let the solids settle out before filtering, I probably wouldn't have ran into many problems here.
Because I included the solids, the vacuum had to pull harder to get the acetone through and a stronger vacuum developed in the flask below.
With a stronger vacuum going, a lot more acetone evaporated, and because we're working with a saturated solution, a bunch of ASA started to precipitate out.
You can actually see the moment here where the problem occurred.
Everything seems to be going more or less okay, but very quickly, a lot of ASA starts to crystallize out.
In the flask below, this really isn't much of a problem, but an issue arises for the filter funnel.
The narrow stem in the filter funnel gets pretty much completely blocked, and filtration comes to a stop.
I tried fixing things by removing the blockage and by diluting things with some fresh acetone, but it didn't really seem to work.
The only way to fix things was to do a proper washing with acetone.
I forgot to film the first washing step and this is the last one, but it's pretty much the same thing.
A little bit of acetone is added to the filter while it's upside down. I swirl it around to dissolve as much ASA as possible, and then I decant everything back into the beaker.
All of the acetone that I'd in the beaker was brought to a boil, and then it was added back to the flask.
The total volume of acetone here is about a hundred and fifty milliliters (150 mL).
The step here was only supposed to be done with about a hundred mils (~100 mL) of acetone, but because of the problems we ran into, and the extra washing I needed to do, the total volume was raised a little bit.
The contents of the beaker, and whatever's trapped in the funnel was washed one last time with fifteen milliliters (15 mL) of hot acetone.
After these three (3) consecutive washing steps there should be little to no ASA left over.
The stuff that remains in the beaker and the filter is mostly filler and it can be thrown out.
The solution is pink because unfortunately, Bayer decided to brand their pills using red dye.
Even after purification, the ASA might be a little bit pink.
To avoid this, it's best to use a brand that doesn't include any dyes in their pills.
Anyway, now we're done filtering and at the bottom of the flask it looks like there's a lot of crystallized ASA.
With just a little bit of swirling though, everything quickly re-dissolves.
Now we set things up for a quick distillation, and I forgot to add a stir bar so I just chuck one in.
So what we want to do now is distill of as much acetone as possible and recover the acetylsalicylic acid.
In the video made by Chem Player, the acetone was simply just evaporated in a dish.
That's a completely viable method, but I wanted to recover the acetone, which is why I'm doing a distillation.
With the heating and stirring turned on, we slowly distill off the acetone.
We'll eventually be left with a white cake, and at this point the temperature should be turned down.
The acetone that's recovered isn't exactly super pure, so I would only keep it for rough washings.
When I go to break things up using a spatula, it's pretty clear that there's quite a bit of acetone still left over.
This can be slowly evaporated off at low heat, or we can use a vacuum.
I already dismantled and cleaned up the distillation apparatus, so I opted to do it by vacuum.
So I pull a vacuum on a flask and I quickly evaporate the acetone.
One important thing to point out here, is if you're using a typical vacuum pump, you need to use a trap.
The trap is extremely cold, usually cooled by something like liquid nitrogen, and it's placed in-between the flask and the pump.
Any solvent vapors that come off from the flask will be condensed and held in the trap and the pump will be protected.
Unless they're specialized, most vacuum pumps can be ruined if you don't use a trap.
I don't really want to get into the details, but I'm not using a traditional pump and I'm using a water aspirator pump, so I don't need to set up a trap.
Anyway, things were pretty uneventful and after pumping on it for something like five or ten minutes, it was relatively acetone-free.
A lot of it got stuck on the sides of the flask, so I used a coat hanger to scrape it off.
Once I've loosened up most of the ASA, it's time to transfer it out of the round bottom flask.
If purity isn't a huge concern, it can simply just be dried off and put into storage, but it was a little bit pink still, so I decided to do a recrystallization.
When I went to transfer it to my two liter (2 L) Erlenmeyer flask it was a little bit annoying.
There was a little bit of acetone left, so the ASA just kept clumping up.
After a little bit of annoyance, and shaking things around, I finally got the majority of it into the flask.
The round bottom was then washed with distilled water a few times.
We're going to be recrystallizing the ASA from cold water and we're gonna need a lot of it, so the amount that we use in these washing steps isn't a huge concern.
After I was done washing things, I topped it off to about one liter (1 L).
I then turned on the stirring and I cranked up the heat.
It's also optional, but I added a thermometer just to see how close I was to the boiling point.
Anyway, as the water's heated up, more and more ASA should dissolve.
The ASA is practically insoluble in cold water, but it's actually quite soluble in hot water.
This allows us to dissolve our ASA in a hot solution, and as it cools down, the solubility will slowly decrease, and the ASA will slowly crystallize out.
We eventually reach the boiling point, but it still looks a little bit cloudy.
To see if this is due to undissolved ASA, I add a little bit more distilled water.
I'm supposed to add boiling water so I can keep things hot, but I was a little bit lazy so I just added some room temperature distilled water.
This really isn't an issue because the solution can just heat up again, the real issue we have here is this yellow crap that's floating around.
To get rid of this junk and clean up our solution, we need to carry out a hot filtration.
A little bit of water is put into another two liter (2 L) Erlenmeyer flask and above the flask is placed a funnel.
The water in the flask under the funnel is brought to a boil and the steam keeps the funnel hot.
In the funnel, I have two or three (2-3) coffee filters to trap out any of the solids.
When doing a hot filtration, it's important to keep everything hot and to do it as fast as possible.
The solution that's being filtered is often very close to the saturation point, so if it cools down even a little bit some product can start to precipitate out.
Once everything is filtered through, I remove the funnel, brought it to a boil again and then turned off the heat.
As the solution slowly cools down, our ASA should start to crystallize out.
(music)
Once it's cooled down to room temperature and everything is crystallized, I shake the flask to loosen things up.
To separate off the nice and crystallized ASA, I do a quick vacuum filtration.
Because I have so much ASA to filter off, I'm going to have to do it in two separate batches.
I add as much as I can to the filter, pretty much until it's full.
Most of the water is pulled off, then I wash the ASA a few times with distilled water.
Enough distilled water is added to cover the crystals and then, using a spatula, I mix it around.
I do this to make sure that all of the crystals are washed thoroughly, and to break up any chunks that might be present.
The amount of water used here isn't too critical, but it's still best to use a minimal amount.
After washing it two or three (2-3) times, I keep the vacuum on for several minutes to get the crystals as dry as possible.
The ASA is then dumped onto a piece of paper to dry and I start filtering off the rest of the crystals.
Just like before, the water's filtered off, I wash the crystals two to three times (2-3) using distilled water, and then I let it dry under vacuum.
All of the crystals were combined on the same piece of paper and allowed to dry.
Under the paper I have a pretty big wad of paper towel, which helps suck up some of the water.
The ASA here is nearly white, but if you look closely it's very slightly pink.
The red dye that's used is supposed to be water soluble, so I really thought a recrystallization would get rid of it.
Anyway, clearly it didn't and the crystals are slightly pink,
but this isn't a huge issue. The amount of dye present is super small.
After letting it dry for about a day, I weighed the crystals and the recover was about ninety-four grams (94 g).
This is a pretty decent recovery, and most of the ASA was probably lost in the crystallization, in the washing steps and various other transfer steps.
As I mentioned in the intro, all of the ASA that's recovered here is going to be hydrolyzed into salicylic acid (IUPAC: 2-Hydroxybenzoic acid).
Instead of doing a base hydrolysis like I did in one of my early videos, I've decided I'll do the much easier acid hydrolysis.
With that being said, I don't think that's the next video I'm gonna post and [I] think I'll cover the 'silver mirror' and the Tollens' test next.
As usual, I'd like to thank everyone who's supporting me on Patreon. Anyone who supports me with five dollars (≥$5) or more will get their name at the end of the video like you see here.
Eventually, I hope to get some higher tiers going, and also add some more rewards to the one dollar ($1) and five dollar ($5) tier.
I also think I'll add some sort of voting system so that supporters can influence which videos I post next, and the videos that I film next.
Anyway, these are the videos I've already filmed and the ones that I plan to film. If you have any suggestions, please let me know in the comments.