Today we're going to use sulfamic acid to prepare ammonium methyl sulfate, which we'll

be using to make the sulfamic acid reactions.

Sulfamic acid is available as high-end kettle and coffee machine cleaner and de-skiller.

Because it's food grade you can get 99% pure sulfamic acid crystals like these.

We're starting with 125 grams of sulfamic acid crystals.

We set up a dry 500 ml flask.

Now we're going to add the sulfamic acid to this.

Some nasty lumps stuck in the funnel.

Okay here we go.

Now we've measured out 75 ml of dry methyl.

In theory the reaction requires just over 50 ml, but we're not sure how much it's going

to take to either dissolve the sulfamic acid or to drive the reaction to a considerable

degree.

So we'll start with this and see how we get on.

This goes into the flask with the sulfamic acid.

It doesn't look very soluble.

But let's eat it and see.

We've set up for reflux using a nice strong heat source and a reflux condenser running

cold water.

At the top of the condenser we've got a DIY dryer.

Drying tube containing anhydrous calcium chloride.

We read that the product is very hydroscopic.

So we kept this on throughout the reaction.

The mixture is heating and starting to boil.

And soon we've got a reflux of the methanol starting up.

We turn up the heating and make sure we've got a nice strong reflux in the flask.

We kept this going for an hour.

And then removed the flask from the mantle just to see how we were doing in terms of

the sulfamic acid dissolving.

Not too impressive as you can see.

This is obviously a slow reaction.

So we decided to add a further 75 ml of methanol to the flask to see if this would help speed

things up.

After all, we can always distill it off again later.

And back to reflux.

There's a little bit of bumping in the flask.

But it's not too bad and probably helps stir the solids up a bit.

Here's the mixture after a further hour of refluxing.

Quite a lot of the sulfamic acid has dissolved, but there's still a large mass of white solid

in the bottom of the flask.

So we decided to add a little more.

And back on the heat again.

We've now got 125 grams of sulfamic acid and 225 ml of methanol in there.

We let this reflux for a further 2 hours in order to see if this would now make a big

difference to the speed.

But two hours later it's looking promising.

We reflux again for another hour and a half.

And this is what we got.

The clear mixture.

Well, it only took 5 and a half hours in total to get here.

We let the mixture cool a little.

Making sure that it was detected from atmospheric moisture.

And then set up for simple distillation to remove as much of the excess methanol as possible.

And then set up for a final distillation.

The still warm mixture boils pretty rapidly.

And pretty soon we've got methanol distilling off the reaction mixture.

Distillation is pretty vigorous with methanol boiling at under 70 degrees C, so it's pretty rapid.

At a point in time we noticed that a white film appeared inside the boiling flask,

and distillation of methanol seemed to slow down a bit.

We checked and at this point we had collected around 115 ml of methanol.

In theory that still leaves us with just over 50 ml excess to collect.

So we attached our filter vacuum pump and used this to see if we could draw off the remaining methanol.

We collected 145 ml in total but then even the pump couldn't draw off any more solvent.

And the contents of the boiling flask were very hot.

180 degrees C, probably dangerously close to decomposition point.

So we stop here.

The contents of the flask remained liquid for a while.

But soon started to solidify against the cool side of the flask.

And somewhere around 100 degrees C they solidified completely.

This is good because sulfamic acid has a much higher melting point around 200 degrees.

Whereas ammonium methyl sulfate has a melting point of 120 degrees.

We placed a little bit of the solid product in a glass petri dish.

Although we read that the product is very hydroscopic and absorbs atmospheric moisture rapidly.

We couldn't see any evidence of this, even when left in the air for 20 minutes.

Next we decided to dissolve some of the product in water so we could conduct a few experiments.

Dissolves pretty easily.

Probably a bit easier than sulfamic acid.

First let's test the pH of the solution.

Still strongly acid.

So we're guessing that there's still some unreacted sulfamic acid remaining in here.

Unfortunately pH isn't going to give us any idea of how much.

OK on the left is our solution of product.

And in the beaker on the white square on the right is a solution of sulfamic acid.

Let's do a few tests.

We've put a bit of each solution in the test tubes.

First we're going to add some calcium chloride solution.

Any precipitate should tell us if there's sulfate present.

No in both cases.

Remember, methyl sulfate is not sulfate.

They are different and the calcium salts are soluble.

OK we've got some clean tubes and some more of each solution.

This time we're adding some strong warm sodium hydroxide solution.

Any ammonium salt present should generate ammonia gas.

Well, we can actually see anything happening visibly.

But let's place some moistened indicator paper at the top of each tube.

From the sulfamic acid on the right, neutral pH.

On the left though from our product we've got an alkaline reaction.

And the tube has an aroma of ammonia.

This is good evidence that we've got an ammonium salt present in our product.

Well here's our product, completely solidified into the flask.

We heated on a hot plate gently to melt the solid.

And then poured it out onto aluminium foil on a cold work surface.

It crystallized pretty rapidly so it was only in contact with the air for about one minute.

Some interesting looking crystals also started to form inside the flask as it cooled.

Here we go.

157 grams of crude ammonium methyl sulfate as a dry white solid.

It's definitely got some residual methyl and a little bit of sulfamic acid in there.

At this way, the maximum yield it could be is 94%.

We're guessing that it's probably somewhere between 85 and 90% pure.

We'll use this as is for our subsequent work.

Let's see the reactions and see if this good enough for the job.

A nice little reaction, but it takes time and patience.

Thanks for watching and stay tuned.

Transcription by ESO. Translation by —