today we're back with a follow-up in a previous video we prepared acetyl chloride by bubbling .
HCl gas through a mixture of acetic acid and acetonitrile today we're going to do it again .
but on a larger scale and taking a few more precautions in order to see what yield is .
practically possible let's first do a quick tour we've got a large 1 liter flask which .
is going to be our hydrogen chloride gas generator sitting on this we've got a .
pressure equalized addition funnel so we can add sulfuric acid then we've got .
the makeshift calcium chloride drying apparatus for the gas produced which we .
assembled out of two adapters this leads to a dry plastic hose which will lead .
the dry hydrogen chloride gas to our reaction vessel this then attaches to a .
glass tube via some PDF e plumbers tape and we've got this going through a .
thermometer adapter so everything is nice and airtight the reaction vessel is .
a 500 mil to neck flask which is sitting in a bowl .
which we'll use to cool the mixture the glass tube goes into the bottom of this .
and we've got a magnetic stirred bar set up to stir the reaction mixture and then .
on top of the flask we've got an adapter leading to another hose and this leads .
finally to a calcium chloride drying tube to prevent moisture from getting in .
okay that's the setup you can improvise this differently but make sure you've got .
the calcium chloride drying for the gas and for the hydrogen chloride gas and for the oxygen chloride gas .
the atmospheric outlet and make sure you've got good stirring and cooling for .
the reaction mixture okay let's set up the gas generator here we've got 200 .
grams of anhydrous sodium chloride crystals make sure you use the anhydrous .
white fine crystalline salt dry in the oven that high temperature for a few .
hours if you're uncertain we've placed this into the large liter .
flask and now for the sulfuric acid .
here's 150 mils of concentrated 98% sulfuric acid there's a few salt .
crystals left in the beaker which is the white residue you can see we place this .
into the addition funnel okay now for our reactants firstly here's 50 mils of .
glacial acetic acid it's important that this is completely free of water and .
if you are in doubt then it might be worth distilling before you use it .
this goes into our reaction flask and here we've got 46 mils of acetone nitrile .
which again has to be pure and completely free of water this also goes .
into the reaction flask .
okay we're nearly set up now we reattach the tubes and make sure everything is .
airtight let's get our reaction mixture stirring and we place ice and water into .
the bowl to cool it down let's start gas generation slowly to begin with the fog .
fills up slowly to begin with the fog fills up slowly to begin with the fog fills up .
the generation flask and we've got air initially displaced bubbling through .
the reaction mixture nicely the temperature is cool and we'll try to .
keep it below 5 degrees during the entire process we're hoping that any .
residual water in the hydrogen chloride gas will be removed by our drying .
apparatus with the calcium chloride granules we're watching the outlet dry .
out the gas is moving too closely but we can't see any cloudy fumes of HCl gas .
coming out the HCl is absorbed quite readily into the acetic acid and .
acetoneitrile mixture one thing we notice is that when the sodium chloride .
salt is free of any water the addition of sulfuric acid doesn't seem to .
generate any heat as the HCl is generated so if you find your generation .
flask warming perhaps your salt isn't so dry .
There's still no sign of any HCl fumes at the outlet but as a precaution we're going to switch on the ventilation now anyway.
With the stern off you can see that the gas is being absorbed rapidly as it bubbles through.
It takes about 40 minutes to add all the sulfuric acid to the sodium chloride.
There's still a very vigorous gas generation going on at the end of addition though.
To complete the gas generation we place a metal bowl under the gas generation flask, and then fill it up with boiling water.
This loosens the mixture up and allows all the salt to react.
And so it is.
Soon after for the first time, we can see some fumes of HCl gas escaping from the apparatus.
And from the bubbling in the flask it looks as though no more gas is going to dissolve in the reaction mixture now.
We let the HCl continue to generate for another 20 minutes and allowed it to bubble through the chilled reaction mixture just to be sure that our reaction was as complete as it could be.
Here's our reaction mixture.
Holding the flask it's definitely increased in weight quite substantially.
We chilled this down for about 30 minutes.
Now for 24 hours.
And here we go.
The contents of the flask have crystallized into a solid, with a small amount of liquid present in there.
So we set out to distill this directly from the reaction flask.
The C-chloride boils at just over 50 degrees C so it should be pretty easy to collect.
We'll use the thermometer to check the vapor temperature.
And a nice dry collection flask.
On gentle heating we rapidly got a lot of HCl gas evolved from the apparatus.
So we set up a hose.
The mixture started to boil very quickly.
The temperature of the vapor was around 50 degrees C.
We kept collecting lead distillate until the temperature started to rise.
At this point there was also a pause in the boiling in the flask.
So we assumed that the vapor was still there.
And assumed that this is the end.
The mixture also liquefied completely with no more crystals.
We switched off the heat and allowed the apparatus to cool.
Here's the boiling flask.
We'll come back to this later on.
And here's our clear distillate.
First of all let's get this into a measuring bottle so we can weigh it.
And here we go.
The moment of truth.
20.5 grams of acetyl chloride.
Which we assume is fairly pure from the distillation temperature.
Doing the maths.
This corresponds to a 30% yield on our starting acetic acid or acetonitrile.
This is a lot better than our previous attempt.
And is now into the region of being a viable solution.
The process given how cheap the starting materials are.
Provided that is that you can get hold of acetonitrile.
We will have a play with this behind the scenes.
Next we want to see if the yield changes by using an excess of acetic acid.
We'll let you know if there are any improvements we can find.
Okay let's now do a couple of tests on the product.
First of all the classic.
The reaction with water.
It's not miscible.
But as you can see it reacts rapidly.
Sometimes forming a trail of HCl bubbles as it does.
Now for something a bit different.
Here's a small beaker and inside it we've placed a few grams of anhydrous sodium acetate crystal.
And we've placed a thermometer in there as well.
Now note the ambient temperature to start with.
80 degrees C.
Now for a couple of mils of acetochloride.
And immediately the temperature jumps right up to nearly 80 degrees C.
The reaction with sodium acetate is very exothermic.
Generating sodium chloride and acetic anhydride.
If you want to use your acetochloride.
To make acetic anhydride.
Then check our other video on how to do this.
And now for the liquid remaining in our boiling flask.
We stoppered this up and chilled it down again in the freezer for a few hours.
Here's the result.
Lots of white crystals again.
This is acetamide hydrochloride.
And the liquid is a mixture of unreacted acetic acid and acetonitrile.
Which probably still contains some dissolved acetamide.
Let's filter this off.
The mixture still fumes in air very slightly.
But it's clear that the acetochloride is now removed.
And here we go.
22 grams of acetamide hydrochloride as a white fluffy crystalline powder.
It still smells of acetic acid.
But otherwise it looks really clean and pure.
And this is a useful product in its own right.
You could even try to recycle this back into acetonitrile again if you wanted.
But you'll only recover at most about 15 to 20% of what we originally started with.
Unfortunately.
So there we go.
Acetochloride from acetonitrile.
There are other ways but we haven't found one that doesn't involve powerful chlorinating agents which are very difficult to obtain.
Have a look at our previous videos for ideas of what you can use acyl chlorides for.
Including interesting Friedel-Crafts reactions.
Thanks for watching.
And stay tuned.
We'll see you next time.
Bye.