Bromine is a really cool element,
and it's actually one of the few elements that can exist as a liquid at room temperature.
It's a member of the halogen family,
which includes other elements that you might have heard of
like fluorine, chlorine, and iodine.
It's a pretty useful chemical in organic chemistry,
but in general, I want to make it because it's just a cool element.
Its very dark red, almost black colour makes it look pretty scary.
On top of this, it fumes a lot,
and a lot of brownish-orange fumes come off (which is also pretty cool)
With that being said, it is cool, but it's also extremely dangerous,
so, when working with it a lot of care has to be taken.
I actually made bromine in a previous video, but I want to explore the synthesis again using different chemicals.
Like last time, I also want to use chemicals that are easily purchased from the store.
In my previous video, I used muriatic acid (IUPAC: hydrochloric acid / HCl), sodium bromide (NaBr) solution for pools and pool chlorinating agent.
In this video, I'll also use the same sodium bromide pool solution, but instead of muriatic acid and pool chlorinator...
I'll use manganese dioxide (IUPAC:Manganese(IV) oxide) from batteries and sulfuric acid drain cleaner.
I should mention that I did this synthesis just for fun, and it's not nearly as good as my previous one.
My previous one has a much better yield and it's a lot easier to clean up because we don't have to use manganese dioxide.
In the future, I do plan to do an element series video for bromine, but that might take a little while because I have a lot on my plate right now.
Anyway, with that being said, we can get started with the synthesis.
Here you can see all of the chemicals that I used, and from left to right:
I have sulfuric acid drain cleaner, manganese dioxide and sodium bromide solution.
Both the sulfuric acid and the sodium bromide solution can be bought directly from the store, but I had to prepare the manganese dioxide.
The manganese dioxide was prepared by extracting it from carbon-zinc batteries.
I have a full video showing how I did this, and I'll provide a link to it in the description.
Anyway, now for quantities.
I used four hundred milliliters of the thirty-five percent sodium bromide solution (400 mL 35% NaBr)...
A hundred and eighty-six milliliters (186 mL) of the ninety-three percent (93%) sulfuric acid drain cleaner and about seventy-nine grams of manganese dioxide (79 g).
Both the drain cleaner and the manganese dioxide were used in roughly a twenty percent (20%) excess.
I used such a large excess mostly because the manganese dioxide from the batteries is contaminated with a significant amount of carbon and the twenty percent excess will try to account for this.
I should also mention that this reaction can be done using potassium permanganate (IUPAC: Potassium manganate(VII) / KMnO₄) instead of manganese dioxide.
However, I chose to use manganese dioxide because for most people, potassium permanganate is a lot harder to get.
To a one liter (1 L), three-necked round bottom flask, I added the seventy-nine grams of manganese dioxide (79g MnO₂).
Directly on top of the manganese dioxide, I pour in the four hundred milliliters of the thirty-five percent sodium bromide solution (400 mL 35% NaBr).
I then remove the funnel and I drop in a large stir bar.
You can see here the final setup of the simple distillation that we'll be carrying out and I start lubricating all of the joints with a little bit of sulfuric acid.
When making bromine, I think sulfuric acid is the best sealant to use for the joints.
You can see though, when I put the stopper back in, the sulfuric acid reacts with something in the joint.
I'm not sure what this is, but it won't affect the reaction.
I guess I just didn't clean the flask as well as I thought.
This is what the apparatus looks [like] with all of the joints sealed, and if you look to the left you can see that there's an addition funnel attached.
To the addition funnel is where we add the hundred and eighty-six milliliters (186 mL) of the drain cleaner.
Pure, clean sulfuric acid is colorless, but when you buy it as a drain cleaner, they have colorants and other things inside.
For some reactions it won't matter, and this is why in a previous video I showed how we can clean up the sulfuric acid drain cleaner, but for this reaction it really isn't an issue.
The reason we use an addition funnel, in general, is because the sulfuric acid is what's gonna get the reaction going.
By using the addition funnel, we can slowly add the sulfuric acid and we can keep the reaction rate under control.
If everything's added at once, it could lead to a violent boil and a pretty dangerous situation.
On our right side, we set up our inverted funnel trap and I start by adding a little bit of sodium thiosulfate (Na₂S₂O₃)
On top of the sodium thiosulfate, we add just enough water to cover the opening of the funnel.
Sodium thiosulfate is a reducer and it will trap any of the oxidizing bromine vapors that might escape.
Heading back to the reaction flask, when we're ready to get things going, we can open up the addition funnel and start to add a little bit of sulfuric acid.
The addition of the sulfuric acid to this mixture is gonna be pretty exothermic, meaning it's gonna heat things up.
So, it's important to add the sulfuric acid slowly, to keep the reaction under control, because as we add it the solution is going to boil eventually.
It's important to have very strong stirring, to make sure that the sulfuric acid that's added gets thoroughly mixed.
To do this, we're using that magnetic stir bar that I mentioned earlier and I have a magnetic stirring plate that's running below.
It has a spinning magnet in it and the magnetic stir bar will follow it as it spins.
It might be a little bit hard to see, but the fumes actually have a faint orange color.
As we add more, it'll take on a darker and darker reddish-orange color.
If you look above to the part where the distillation apparatus is connected you can see that some of the orange vapors are starting to make it over.
As we add more sulfuric acid, the concentration of the bromine vapors will get higher and higher and the red color will get stronger and stronger.
When we move over to the right side and we look at our collecting flask, we can see it's filled with this orange vapor, but no bromine has collected.
The vapor is just strongly colored, but there isn't actually enough there to condense it into a liquid.
Also, you should notice that the receiving flask is now on ice because as the bromine collects, even in liquid form it has a strong tendency to vaporize.
By keeping it cool in an ice bath, we can limit how much vapor comes off.
Bromine has a boiling point of fifty-eight point eight C (58.8 ℃), which means that it's not too hot too touch.
When I put my thumb against the glass, it actually cools it down enough that bromine starts to condense.
I thought it was cool that even after I take my finger away, you can see where my thumb was and it's still condensing bromine.
At this point, you can see the dark red vapor front of bromine almost making it over.
What's interesting is that at this point we haven't used any external heating. All of the heat that's being provided is from the reaction itself.
Eventually, some very nice, nearly black drops of bromine will start to come over.
At the bottom of the receiving flask, we can see the black, dark bromine liquid starting to build up.
Another thing that I thought was cool was if I placed my hand onto the flask, I can actually stop the distillation from happening.
You can clearly see the vapor front of bromine being pulled down, and when I take my hand away it starts to climb again.
As I said before, we still haven't used any external heating and you can see on the left that there's still quite a bit of sulfuric acid left to add.
I start to add the rest and you can see here it's even darker than before.
With a steady rate of sulfuric acid dripping in, it provides more heat and more bromine is able to boil and come over.
When we go to the side of the receiving flask, we can see that the dripping rate is pretty steady.
We can see the reaction that's going on here, where we have sodium bromide, manganese dioxide and sulfuric acid...
All reacting together to form bromine, potassium bisulfate, manganese sulfate and water.
All of the products should remain in the reaction flask, except for the bromine, which is being distilled off.
The manganese dioxide is acting as the oxidizing agent and it's oxidizing the bromine anion in sodium bromide to elemental bromine.
Because it's just acting as an oxidizing agent, it can be replaced with other oxidizers.
Some examples of other oxidizers are things like potassium permanganate, or hydrogen peroxide (H₂O₂)...
but like I said before, I chose manganese dioxide because I thought it was the easiest to get for most people.
Eventually though, when all of the sulfuric acid has been added, it will stop coming over and we're gonna need to provide an external source of heat.
To do this, I used the electronic heating mantle that you can see below the flask.
As things start to heat up again, more bromine should start to come over.
The reaction is done when the contents of the flask start to froth.
You can see here that the flask is now black and it's climbing up into the distillation apparatus.
Because of this, some of the contents [were] able to froth over and make it into the receiving flask..
This is really undesirable, but it's not the end of the world and it can be fixed with an extra cleaning step.
Anyway, once it's done, the flask is taken off heat and allowed to cool.
Just pretend that you can't see me standing there in the background.
Here, I want to illustrate the purpose of the inverted funnel trap.
As the apparatus cools down, the air volume inside it will shrink, and because of this it pulls a slight vacuum.
If we used just a tube as our trap, this would cause the water to be sucked up and it would end up in our receiving flask.
Using the inverted funnel trap, you can see the water sucked up, but eventually the water level will go below the opening of the funnel.
At this point, air's pulled in instead, the water level in the funnel will drop and we don't get anything being sucked into our receiving flask.
Here we can see the final yield of our bromine.
For now, though, I have to put this aside as I clean up the rest of the apparatus.
To clean things up, I use a solution of sodium thiosulfate like I used in the trap.
The bromine is a strong oxidizer and the sodium thiosulfate is a reducer and these two things will react together.
The bromine will react to reform sodium bromide, which will dissolve into solution, and isn't dangerous.
You can see that after it's add and it's just sitting there, the intensity of the bromine vapor actually starts to decrease.
And after sitting there for several minutes, the color of the bromine vapor is completely gone.
Now we need to neutralize the contents of the flask.
To do this, we start off by adding the sodium thiosulfate solution that was in the addition funnel.
Surprisingly, there wasn't much bromine leftover, so that small amount of sodium thiosulfate solution actually neutralized it all.
I then just used a squirt bottle with some water to clean off the walls and we can see that there's no orange bromine vapor.
Now, for the fun part.
Some of the stuff frothed over and got into the receiving flask, and to separate this out it's going to have to be filtered.
I opted not to do a gravity filtration because the bromine would destroy the paper, so I didn't really have much of an option.
This actually worked really well, but my poor vacuum pump was punished pretty badly.
We only needed a slight vacuum to pull the bromine through, so I intermittently turned on and off the pump.
My pump is already punished enough, and if we leave it on it could easily vaporize the bromine that's come through, make more vapor and punish it even worse than it needs to be.
You can see here that I opted to drain it directly into a separatory funnel.
This is because when it frothed, a lot of water also came over and I'm gonna need to separate this, as well.
In the filter flask, it looks like bromine, but it's actually a lot of manganese and carbon that we filtered out.
It is heavily contaminated with bromine, though, and it will have to be neutralized.
Once it's all in the separatory funnel, if you look at the top, you can actually see a water layer.
So, to get rid of this, I used a beaker and I drained our bottom-layer bromine into it.
The top water layer is pretty contaminated with bromine, so it needs to be drained off and neutralized using sodium thiosulfate.
The now cleaner bromine is then poured back into the separatory funnel.
You can see just how much fuming is occurring, so it's really important to do this in a well ventilated area.
On top of the bromine, I poured in about twenty-five milliliters (25 mL) of concentrated sulfuric acid.
Sulfuric acid really loves water and by adding it to the bromine we can dry it up.
The next step is to take it off of the stand and to shake it thoroughly.
It's important to vent it frequently, to prevent any pressure from building up.
It should be pretty obvious, but this step is pretty dangerous.
Anyway, once we think it's been thoroughly mixed, I place it back on the ring stand and let the layers separate.
Once the layers have settled, we can drain the bottom bromine layer into a round bottom flask.
The top layer, which is concentrated sulfuric acid, must be drained into a beaker containing water.
Afterwards, we can add sodium thiosulfate to neutralize it, but it's important not to put the sulfuric acid directly into a sodium thiosulfate solution because it can react pretty strongly.
To clean up the separatory funnel, I pour in some more solution of sodium thiosulfate.
I forgot to mention it earlier, but the reason the sodium thiosulfate solution becomes opaque is it reacts with sulfuric acid to release elemental sulfur.
The sodium thiosulfate solution in the separatory funnel is then drained into the beaker to neutralize any bromine that was in there.
I also used some sodium thiosulfate to clean out the receiving flask that we used in the distillation.
You can see that after I cap and shake it, everything becomes totally colorless, indicating that all of the bromine has been neutralized.
This is the final yield of bromine, which is about seventy-seven point five grams (77.5 g).
This represents a percent yield of about fifty-four percent (54%), which isn't great, but also not too terrible.
As I mentioned in the introduction, though, my other method is more efficient and it's a lot cleaner.
In this one, you have to deal with a lot of leftover carbon and manganese dioxide, which gets everywhere and it's a pain to clean up.
This is more for people who have a hard time getting their hands on pool chlorinating agents like TCCA (Trichloroisocyanuric acid, IUPAC: 1,3,5-Trichloro-1,3,5-triazinane-2,4,6-trione)...
which is required for the other video.
I made a very sophisticated temporary storage container for this bromine.
I plan to use it very shortly after making it, so there was no use in [placing it in an ampoule].
For long term storage, though, the best thing to do is to put it into ampoules like I did in my previous video.
Anyway, that's all I have to say for now. Like I said in the introduction, I will be doing an element series for bromine at some point, but I'm not sure when that will be.
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, instead of stockpiling videos, I've decided I'm gonna publish them as soon as I edit them, so in the next month or so there's gonna be a lot of videos coming out.
On my Patreon I also added a milestone, and if we get to two hundred and fifty dollars per video (250 CAD) I'll commit to doing videos for at least six months.