in a previous video you'll remember that we started with some particularly

concentrated urine and converted this firstly into urea nitrate and then

reacted this with sulfuric acid to obtain a small amount of nitro urea

we're interested in doing some experiments with nitro urea so we

thought we'd make a larger batch by trying to nitrate urea properly so let's

have a go and yes my voice is sounding particularly

husky today okay here's what we're going to

use for the first part of the reaction instead of yellow piss we've got 25

grams of pure white urea crystals here looks a little bit nicer than in our

previous video and to react with this we've measured out 32 mils of 68%

concentrated nitric acid our acid has a density of 1.42 so the stoichiometric

amount of acid will be around 30 mils we're

using a small amount of nitro urea to make this reaction with sulfuric acid

a slight excess.

And here's a 200 ml beaker equipped with strong magnetic stirring for the reaction.

Strong stirring is important for the first part of the reaction, but you may also need

to stir by hand as the mixture thickens.

We've got this on a stirrer, and first of all we're going to add the urea to the beaker.

Now on its own this isn't going to stir very well, so we're now going to add 10 mils

of water to this in order to create a slurry.

Some will dissolve, but not all.

Okay let's get stirring.

And now we're simply going to add the niacinamide.

We're going to add the nitric acid to the urea and water mixture in the beaker.

This needs to be done slowly because the reaction will produce some heat.

A small amount of acid vapor coming off.

The mixture gets pretty hot as the nitric acid reacts with the basic urea to form a

nitrate.

The mixture thickens as the salt forms and crystallizes.

And at this point our magnetic stirring breaks down.

The reaction needs a little while to complete, so to help we stir by hand for a few minutes.

The evolution of heat continues for about 10 to 15 minutes.

And now we wrap this up and chill it for an hour in the fridge until it's completely cool.

Okay here we go an hour later.

You'll notice that the mixture is now a lot more solid and the product has crystallized completely.

Well, there's some water and excess nitric acid still in here.

So we're going to remove what we can using a vacuum filter.

Let's get the product in.

Once it's all in we pack the mixture right down so it's hard in the filter.

This will help draw liquid out.

It takes quite a while to remove the majority of the liquid.

We leave this running and drying on the pump for about 30 minutes.

So here's the small snow white mountain of our intermediate product, urea nitrate.

We've got 55 grams here which suggests a pretty much quantitative conversion of the urea starting material.

But the solid is still acidic and slightly damp.

If you wanted a pure product as an intermediate then you'd need to wash this well with ice cold water, and then dry thoroughly.

We don't need to do this because we're going to move straight on to the next step.

Converting this urea nitrate into nitro urea.

So let's get set up.

In order to do this next step on this larger scale it is vitally important to have good temperature control.

So we've got a large bowl here filled with ice and water, and we've added some salt to reduce the temperature down.

Let's prepare our main reagent for the reaction.

Here we've got 150 mils of 98% concentrated sulfuric acid.

We've placed this into a 500 mil beaker and we've chilled this down in the freezer to as low a temperature as possible.

The wrap on the top was there to prevent moisture from getting in.

So we've placed this into the ice bath, with a magnetic stirrer in the acid, and let's see what temperature we're starting out at.

About minus 7 degrees C.

Okay this is pretty cold, so let's try this out.

Here's the 55 grams of very slightly damp acidic urea nitrate crude product from the first step.

We're going to add this slowly to the acid mixture, whilst keeping the temperature as low as we can.

Let's rock and roll.

Temperature has immediately come up after just a few spatula fulls of urea nitrate added.

So we'll keep this stirring and let it chill down again.

And then slowly add more urea nitrate so the temperature is kept below zero.

If you're cautious you shouldn't get any brown fumes of nitrate.

This is because the acid is not a very high amount of nitric dioxide produced.

Have ventilation ready though in case you do as this is highly toxic.

Total addition took about 40 minutes to complete.

After this we let the slightly viscous mixture stir in the ice bath for a further 30 minutes.

Ok here we go 30 minutes later.

So time to very gently start diluting the reaction mixture.

We start off by adding a single ice cube to the beaker.

This rapidly melts in the sulfuric acid, and a white precipitate starts to form.

We continued adding ice cubes slowly, and monitoring the temperature of the mixture.

The highest temperature it got up to was 20 degrees C.

We continued ice cube addition until the total volume of the mixture was about 350 mils.

Ok here we go.

Lots of solid product in here.

So it's time to filter this off.

The fine white solid does take a while to filter and dry.

It's still got a lot of sulfuric acid in at this point, so we need to wash thoroughly

with ice cold water.

It takes a long time to get it to a reasonable state of dryness, but here's the end result.

31 grams of fairly dry nitro urea product, which corresponds roughly to a 70% yield from

the starting urea.

It's probably still got a little bit of water in it, and it's really hard to get

completely dry, but it's a free flowing slightly clumpy powder as you can see.

We're going to be using this in some follow up reactions, but you might be excited about

this product for the wrong reason because you've read that it's highly explosive.

Well, let's just put that theory to the test.

Here's a little bit of the driest powder.

Lights off.

As you can see it rapidly decomposes when heated, but there's no fireworks.

Like we saw in the previous video.

To get this to explode you'd need to use a shockwave provided by a detonator.

Simply burning it won't do anything.

But we can see there's hardly any residue at all, so we've got a nice clean product.

Now you might ask why we'd do this reaction again, but it does demonstrate an important

point.

When we did this before on a tiny scale we could get away with not much cooling and not

being too careful and we still got a reasonable product.

But we've got a nice clean product.

But on a larger scale like this, if you tried to do this without care and without the degree

of cooling we used, it's easy to get hardly any yield at all due to decomposition during

the reaction.

When you scale things up, often the game changes.

That's all for this video.

Stay tuned and hopefully the sore throat medicine will work soon.

Thanks for watching and I'll see you next time.