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An organic nitrile in the presence of a carboxylic acid and hydrogen chloride gas will apparently dehydrate the acid forming an amide. In the process the corresponding acyl chloride is produced.

We did a test and bubbled HCl gas through a equimolar mixture of acetonitrile and acetic acid at room temperature until no more would dissolve.

The resulting solution left overnight and cooled yielded crystals as shown here, exactly as the reference said it would.

We filtered off the crystals and then distilled the fuming filtrate liquid.

We used a water bath and up until around 80 degrees C we only got a very small amount of liquid coming off.

However what we did get fumed strongly in air and reacted very rapidly with water.

So we decided to scale up and see if this was for real.

We assembled an apparatus which would allow us to slowly generate HCl gas and bubble this through the liquid mixture whilst suspended in an ice bath and completely closed to the atmosphere.

We used a distillation adapter, some PTFE tape, and a small glass tube and this worked well.

We added an addition funnel so that we could add salt.

We added sulfuric acid slowly to sodium chloride salt to generate our HCl gas.

First we measured out 130 grams of sodium chloride and placed this into the gas generation flask.

Then we measured out 210 grams of concentrated 98% sulfuric acid and placed this into the addition funnel with the tap closed.

We measured out 43 mils of dry acetonitrile and poured this into the reaction flask.

Then we measured out 48 mils of glacial acetic acid and added this to the acetonitrile in the flask.

Once added we swirled the flask.

We swirled the flask in order to ensure the liquids were completely mixed together.

Then we assembled the apparatus and attached a makeshift calcium chloride drying tube to the atmosphere outlet.

We put ice and salt in the water bath to get the temperature down to below 5 degrees C.

Then we began a slow addition of the sulfuric acid to the sodium chloride in the gas generation flask.

First we got a bubbling as air was displaced.

Then we noticed that the HCl gas was dissolving in the liquid.

When we did the first test reaction we noticed that the reaction mixture got quite warm.

So we went slowly and kept the temperature low in the water bath.

We found a slow rate of acid addition which kept the gas dissolving in the liquid and throughout the reaction.

Hardly any HCl gas seemed to escape from the drying tube.

Total addition took around an hour and a half and then we left the apparatus going for a further 30 minutes to ensure all HCl had been generated.

Even at the end we noticed that HCl was still dissolving.

We then dismantled the apparatus and stoppered the reaction flask.

We poured this quickly into a storage container without allowing it to warm up and then placed in a freezer overnight.

After about 2 hours we noticed crystals starting to form in the liquid.

These were quite pretty and like tiny snowflakes.

After 12 hours of chilling it below 5 degrees C.

Below 0 degrees the bottom and sides of the container were covered in crystals.

We decanted off the liquid from the crystals and then set up for distillation.

The liquid fumed in air and also gave off a lot of HCl gas so we really advise using a lot of ventilation.

We used another makeshift calcium chloride dry trap.

As the liquid warmed a lot of HCl gas was produced, presumably dissolved in the solution.

At around 50 degrees C we noticed the liquid starting to bubble and some refluxing occurring in the flask.

Then at just before 60 degrees we saw a colorless clear liquid distilling off.

Distillation was quite slow but we tried to keep the temperature down.

In order to avoid distilling any acetonitrile which we figured would also have a fairly high vapor pressure at this temperature.

Once the vapor temperature rose to 78 degrees C we stopped distilling.

Here's the result 4.7 grams of a clear colorless liquid.

This isn't a lot and if it's pure acetyl chloride only corresponds to a solution.

It has a 7% yield on starting acetic acid.

So the yield is low but we wonder if it can be improved by using a lower temperature, more HCl gas and using fractional distillation.

As you can see the product fumes very strongly in air.

Let's see it react with water.

Let's see it react with water.

It reacts rapidly producing clouds of HCl gas.

No mistake, this is definitely the real deal.

We experimented and found that a small amount of ether could be used to wash the crystals and give us a pure acetamide hydrochloride product.

We'll use this for another reaction.

So in summary, to our surprise this reaction actually does create an acetyl chloride.

To prove this we are going to create a small amount of acetyl chloride which can be separated relatively pure.

A bit of work is going to be needed to play around with this and see if the yields can be increased however.

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