You've all heard of acetochloride, and we've made this in a previous video.

Making it is difficult because it requires some very hard-to-get and restricted chlorinating agents such as phosphorus trichloride.

So we wanted to experiment and see if it was possible to make the iodine analog with cetoiodide,

and then test to see if this would substitute for acetochloride in some reactions.

We set out the 250 ml flask equipped with magnetic stirrin.

Here's our first reactant.

We're using 20 grams of solid iodine.

Iodine is not cheap, so this isn't going to be a very economical reaction,

but we're hoping to be able to recover a lot of this later on.

This goes into the dry flask.

Next we've got 15 ml of glacial acetic acid.

This is an excess of what we need,

which means we're going to need a lot of it.

Our stoichiometrically is about 9 ml of liquid.

We wanted to use excess just to ensure complete reaction,

but it will mean we have acetic acid in our product.

We placed this into the flask together with the iodine.

Then we got the mixture stirrin.

You can see a little bit of the iodine dissolves, forming a very dark red solution.

We set this up with a thermometer dipping into the liquid,

so we could track the temperature.

Next, here's 2.5 grams of red phosphorus.

We know this isn't exactly OTC,

but we want to see if this works before we try anything else.

If this reaction works,

then it's possible that aluminium foil would substitute.

We don't know how exothermic this is going to be,

so we added the red phosphorus slowly to the stirred mixture.

The color changes slightly and develops a yellow and brown tint.

Not much of a temperature increase occurred,

so we continued to add the red phosphorus.

Here we are at the end of addition.

We continued to stir the mixture for 15 minutes

to get everything to rehab.

You can see the mixture has become slightly viscous.

It looks like the iodine has dissolved.

So next we set up for simple distillation of the reaction mixture.

We're using an oil bath to control the temperature carefully.

Acetoiodide apparently boils at 108 degrees,

and acetic acid at 118 degrees C.

So we will get a mixture coming off

pretty soon into heating.

We can see some yellow condensation in the boiling flask.

And we start to get some fumes of hydrogen iodide gas

coming out of the receiving adapter.

These grew more intense as heating continued.

And we had to set up a tube to carry these away

as they are extremely corrosive

and also leave a deposit of brown solid iodine

on anything they touch.

As the temperature rose towards 100 degrees,

we started to get some reflux of a yellow liquid

in the boiling flask.

Distillation was quite difficult to get started,

probably due to the small volume of liquid.

So we jacketed the still head using aluminium foil.

Pretty soon we started to get a brown liquid distilling over.

Distillation of the mixture took about an hour to complete.

Towards the end the boiling flask lost its brown color and high boiling point liquid

with some small specks of residual red phosphorus remained.

Cleaning up the apparatus and anything that the HI gas had touched was achieved using

the dilute solution of sodium thiosulfate, which neutralized any iodine present.

Here's the distillate. 22 grams of a dense brown colored strongly fuming liquid.

This contains some acetic acid, probably also some hydrogen iodide dissolved in the acetic acid,

and hopefully some acetoiodide as well.

Let's do a couple of tests to see what

we've got.

Let's test with water.

The product fumes very strongly in air.

As it hits the water you can see some bubbles and a reaction occurring.

Heat is also produced.

Here's some anhydrous sodium acetate.

Doesn't look like much has happened but the mixture here now has a very strong sharp aroma

of acetic anhydride.

This is us as proof.

We've got quite a bit of acetoiodide in our reaction product.

We chilled the distillate down to negative 10 degrees C

and there was no sign of solid acetic acid.

So we decided to take this to the next step.

We measured out 15 grams of anhydrous sodium acetate.

This should be in excess to what we need.

With the distillate chilled down and stirring in an ice bath,

we then slowly added the sodium acetate to this.

There was some heat evolution, but not enough that the ice bath couldn't handle it.

About a third of the way through addition we noticed the color turning yellow.

Here's a complete addition.

The mixture is pretty solid and we needed to use a spatula to mix it together completely.

It has an extremely strong aroma of acetate and hydride.

We set the flask up for distillation, again using an oil bath.

This time we used a thermometer to track the vapor temperature.

And we used foil as before to insulate the still head.

At about 110 degrees,

we noticed a small amount of reflux in the flask.

And then with the oil bath at around 160 degrees C,

the mixture became a little more liquid,

and we got a lot more liquid refluxing in the flask.

And then we started to get a colorless clear distillate coming off.

Vapor temperature started at 130 degrees C and rose to just over 140.

As the liquid distilled the contents of the flask were a little bit more liquidy.

boiling flask began to dry out distillation kept going for a while

though and we stopped only when no more product came over this took about an

hour in total

here's the distillate we collected 22 grams of a clear colorless liquid with a

strong smell both of acetic acid and acetic anhydride it's definitely not

pure anhydride and contains a lot of acetic acid

but there's definitely anhydride in there too here's a little cold water on

adding the distillate you can see a lot go into solution but there's also some

droplets which sink to the bottom

there's not enough to fractionally distill in order to find out how much

there is here but to purify further fractional distillation would be the way

one thing we wanted to do was see how much of the starting iodine we could

recover from the reaction mixture here's the boiling flask from the distillation

allowed to cool down we added about 60 mils of water to this

and swirled the flask around everything dissolved into solution

we then prepared a solution of 30 grams of ammonium sulfate in 100 mils of water

and added a couple of ice cubes to keep things cool for the reaction then we

slowly added the solution from the boiling flask the brown color first

appeared in the solution which became stronger and stronger as the first

sulfate reacted and oxidized the iodide salt to iodine we added the rest of the

solution and pretty soon with stirring we could see solid iodine precipitating out of the solution

after a few more minutes the reaction was pretty much complete as the

supernatant liquid became lighter in color so we set out for vacuum filtration

we washed the solid iodine thoroughly with cold water

and dried it well on the pump

here's our recovery it's still slightly damp but we got 16 grams here

so we've got about three quarters of the iodine back that we started with this is

okay

we lost a fair bit

hydrogen iodide gas. Perhaps on a larger scale this works out better.

If the distillate ends up only containing a third of acetic anhydride then that's 7

mL of acetic anhydride for 5 grams of iodine not recovered. You decide if the trade is

worth it.

We did a final experiment and checked to see if any anhydride could be produced by simply

mixing together acetic acid, anhydrous sodium acetate, solid iodine and a little red phosphorus.

There was some heat evolution but even after stirring for a few hours we can't detect the

aroma of any anhydride in the reaction mixture. So it looks like the answer is no. No shortcuts

here.

Unfortunately this isn't enough to purify further, but this experiment was only on a

small scale to try to prove the theory.

If you want to scale up then you're going to have to work out how to keep water out

of everything, use really dry apparatus especially for the first distillation of the reaction

mixture, and use very dry anhydrous sodium acetate.

There is also the intriguing possibility of using aluminium in place of red phosphorus.

This would have to involve reacting the aluminium and iodine in an inert solvent in stoichiometric

amounts first.

Then adding the acetic acid and then distilling.

Maybe a high boiling solvent such as a xylene might be suitable.

Have fun, and stay tuned for more reactions.