Hey guys! With hydrogen, boron forms a series of compounds called borane.
They are highly reactive and have an gross energy.
They are even used as rocket fuel.
In today’s video I’m going to show you a few interesting reactions with borohydrides.
We’ll start with ammonia borane.
This is white solid is the simplest molecular boron-nitrogen-hydride compound - inorganic analogue of ethane.
Ammonia borane is obtained by the interaction of ammonium chloride with lithium borohydride in ether.
The reaction intermediate is ammonium boranate,
is unstable and, releasing hydrogen, forms ammonia borane and its polymer.
This reagent ignites easily and burns down with formation of boron nitride and boron oxide.
With liquid oxygen, ammonia borane burns with a blindingly bright, pure green flame.
Ammonia borane has been suggested as a storage medium for hydrogen.
It can be made to release hydrogen on heating, being polymerized first to polyaminoborane, then to polyiminoborane.
Ammonia borane is water soluble and this solution has reduction properties.
Platinum compounds act on it as a catalyst, causing it to actively release hydrogen
It is more correct to say that the catalyst is platinum formed during the reaction.
Look at this process in slow-mo.
The black color formed during the reaction is platinum metal. .
This platinum is the catalyst for the ammonia borane decomposition
In this reaction I put a few crystals of osmium tetraoxide in a test tube and melt them with hot water.
I'll also add some ammonia borane on top.
Ammonia borane ignites instantly on contact with fuming nitric acid.
Later in the video, we will compare the reactions of other borohydrides with fuming nitric acid.
The next borohydride is ortho-carborane. Ortho-carborane is a much more stable white to purple solid
Like all borohydrides, o-carborane is also a highly flammable compound.
When o-carborane combusts, many pieces of something that resembles soot fly out of it.
However, I haven’t found any information anywhere about what these pieces could be.
You can clearly see them forming in slow-mo.
Unlike ammonia borane, o-carborane does not ignite on contact with fuming nitric acid
However, when being set on fire, it burns down instantly with a very loud noise.
And these colorless crystals are decaborane,
which is a quite stable borohydride
and a highly flammable powder at the same time.
I’ve already used it multiple times in my previous videos,
but in this one I’ll show you a truly awesome reaction with it in slow-mo.
Like ammonia borane,
decaborane with liquid oxygen burns with a blindingly bright, pure green flame too.
Despite its stability, decaborane is extremely reactive.
It may even react with some solid reagents.
For example, with potassium superoxide.
And here's the reaction with osmium tetroxide.
I add some decaborane on osmium tetroxide crystals
and melt these crystals with hot water.
And now
I’ll show you what I think is one of the most amazing-looking chemical reactions I’ve ever managed to capture in slow-mo.
This is the combustion of decaborane and nitromethane mixture.
It looks so cool I had to film several takes of it, and I suggest you watch them all.
Many times :D
By the way, ammonia borane and nitromethane mixture burns with a quiet green flame.
The combustion of o-carborane and nitromethane mixture is not that impressive either.
I’ve never come across a description of decaborane reaction with fuming nitric acid,
so go ahead and discuss it in the comments.
I have two takes of this reaction and both of them are in slow-mo, obviously.
So, let’s watch it!
Thanks for watching guys! I hope you enjoyed this video about borohydride compounds.
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Seeya in the next video.