Well, we managed to beg and borrow some THF, and we recently accidentally received some sodium bromate, so why not give it a go?
Let's do a very small-scale experiment first so we know what we're letting ourselves in for
Here's some sodium bromate crystals
Let's add some water to make up a solution
It's not incredibly soluble, so we'll warm it just slightly
Okay, here we go
The lukewarm solution
And here's some tetrahydrofuran
This is a cyclic ether, as you can see, and a five-membered ring with a single doxygen in
It's a watery clear liquid with an unpleasant headache-inducing aroma
Okay, let's get some into the bromate solution
Temporarily, there's a few bubbles of THF in there, but on swirling it mixes completely homogenously
with the aqueous solution
And then basically does nothing
There's no obvious reaction
Let's add a drop or two of 50% sulfuric acid
It sounds a bit scary
Like watering a hot deep fryer
It's a bit scary
Like watering a hot deep fryer
And then it kicks off
Holy crap
That's a lot of bromine and heat
And with just a few small drops of reagents
If we want to scale this we're going to
going to need to do it carefully well we won't spoil the surprise but we did have
a bit of fun with this one later if you're going to do this reaction and do
it small let's look at the setup we're using the large 1 liter flask it's a bit
old the dirty unfortunately this has got good magnetic stirrin and temperature
control could well be important so we've got the thermometer so we can keep a
close eye on this and a very efficient condenser with lots of ice cold water
trust us on the condenser
don't go halves just trust us
ok we're set up so let's start preparing the reagents we need here we've got 30
mils of 50 percent by volume sulfuric acid we're going to use a rather larger
dilution than our test so we're going to mix this with
mils of water let's get this into the flask first in order to tame this we're
now going to add 15.6 grams of solid potassium hydroxide this will convert
the sulfuric acid into potassium hydrogen sulfate still acidic but not
quite as potent
that's such an awesome sound the temperature inside is now about 40
degrees C though so not too much we've got a flask set up in the pooled water
bath so we'll let this come back down to about 20 degrees again
okay here's our sodium bromate this is 42 grams which is going to be the same
stoichiometric amount as the THF we use and the sulfuric acid it's an innocuous
looking white crystalline powder a bit like sugar or salt but don't let it fool
you we'll try to dissolve this in the minimum quantity of water possible
and we get there with about 200 mils of solution volume let's get this into the
flask a white precipitate forms maybe this is just because of cooling or
perhaps it's potassium bromate we're not sure let's get the stern going and
continue anyway and finally here's 20 grams of tetrahydrofuran about 23 mils
about 23 mils
again we want to dilute this a bit so we're going to add 50 mils of water
ok we're now all set and ready to add this very slowly temperature is about 20
degrees in the flask
ok let's do this
well that's an anticlimax let's try again
we did notice in the test at the start that the main reaction kicks off after a
while so perhaps it needs heat to start up so we put the flask on a hot plate and
let it warm up a bit
a little more can't hurt now can it
soon the solids dissolve again temperature is now around 30 degrees C
but they're still not even a hint of yellow bromine color in the mixture so
we keep on heating
and very slowly a yellow color starts to appear in the mixture we're honestly
wondering at this point if we really need to bother with the condenser do not
remove your condenser let's just help it along
I mean another half gram of ta check can't hurt can it
interestingly the bromine color fades slightly on addition
40 degrees see now about this point we suddenly realize that in our excitement
and impetuous miss we've added about a third of the DHS mixture and suddenly
we've actually got some orange colored bromine vapor starting to appear in the
flask
so this is a good sign
now at 50 degrees
yeah
What the heck?
Let's try to jumpstart this thing.
The two Kimpliers looked at each other.
Deep down in the bottom of their stomachs they somehow knew that their sins would shortly
be punished.
Like a guilty child standing in ominous dread outside the Hair Master's office.
As the mixture gradually grew deeper in color they tensely waited for their punishment,
knowing they had unleashed forces beyond their control.
Like the sound of the rod swishing through the air.
The gentle reflux which commenced triggered a sharp apex of anticipation from their senses.
So they quickly switched on ventilation and readied an ice water bath.
And at about 65 degrees they were ready to go.
At about 65 degrees the reaction commenced full swing.
And a door to a hellish, parallel universe opened up in our flask.
We survived.
Actually, we survived.
Actually, we did pretty well.
The ice cold water doing the cooling in the condenser was a good 40 to 50 degrees by the
end.
But it saved us.
We added the rest of the DHF mixture slowly and let the reaction proceed a bit slower
with a gently reflux.
We then left the mixture stirring and refluxing for the next four hours.
The bromine didn't fade away.
If anything it seemed to disappear and then come back to normal.
And then it came back again in cycles.
Weird.
At the end of this time we decided to quench the reaction mixture using saturated sodium
bisulfite solution until the color had disappeared.
Just some strange red blobs jumping around.
Oh.
Ok.
We decanted off the reaction mixture and left the blobs behind.
Let's work this up and see if the punishment from the chemistry demon extends to yield
of product as well.
We extracted the reaction mixture using 240 ml portions of dichloromethane.
And we did it.
We did it.
We did it.
We did it.
We did it.
We did it.
We did it.
We did it.
We did it.
We did it.
We did it.
We did it.
We did it.
And we've got a nice 13 grams of bromine here to play with now as well.
Here's our DCM extraction.
We dried this using anhydrous magnesium sulfate, and then decanted the DCM solution into a
flask.
Okay, let's boil off the DCM and see what's left.
All the DCM is gone and the mixture got to over 100 degrees C, so there's no water here
either.
We've got a pale yellow colored liquid with an unusual subtle aroma.
Reminds us a bit of the seaside.
Okay well it's not much but it is enough to distill, so let's try.
We set up for distillation using a heating mantle as a strong heat source, and a thermometer
so we can record the temperature of the distillate.
We insulated the still head to make it more efficient as well.
On heating the mixture darkened, almost to a black color.
As distillation starts the temperature shoots up.
And then we start to collect the clear liquid distillate.
With a thermometer vapor temperature of 200 degrees C.
Distillation was pretty quick and at the end the black carbon like material was left in
the boiling flask.
In the end this took a dose of Erythritol.
So here's our distillate.
There were no other fractions at all, and it's a slightly pale yellow color, but this
could be some decomposition material that condensed because we could see the distillate
in the boiling flask was colorless.
Here we go.
6.2 grams of a watery product, boiling at 200 degrees C and with an unusual faint aroma
of seaweed.
So what is it?
Well we're guessing you might have figured it out.
It's this rather infamous compound here.
Gamma butyrolactone, otherwise known as gene EL.
It's infamous because it's a sedative drug, a bit like ethanol or chlorohydrate, but quite
potent.
A lot of countries made it illegal a few years back because it was being a bit too widely
abused and the media had a field day about it.
Well we're certainly not planning to eat it.
It doesn't smell very pleasant and having seen the reaction it came from it's not particularly
appetizing.
We'll be celebrating that the reaction worked and that we survived it using something a
bit more traditional.
Thanks for watching and stay tuned.