we recently acquired an interesting chemical sodium hypophosphate it's the .

sodium salt of hypophosphorus acid which can apparently be used together with iodine instead .

of red phosphorus to reduce alcohols to the corresponding alkane first we wanted to see .

if we could prepare the acid from the salt so we started by measuring out 100 grams of .

sodium hypophosphate crystals these are the dihydrate salt the theory was to see if we .

could perform the displacement reaction using a strong mineral acid .

so we measured out 30 mils of concentrated hydrochloric acid initially this is half the .

molar equivalent we placed the salt on a hot plate and then added the acid to the crystal .

these seem to dissolve and a much lighter colored solid appeared in the suspension this is a good .

sign that sodium chloride is being created and precipitated .

due to the concentration we gave the mixture the good stir and heated it on a hot plate we .

then prepared a further 30 mils of concentrated hydrochloric acid which should make up to one .

mole of HCl per mole of sodium hypophosphate we added this to the hot mixture and stirred again .

you can see that the white crystalline deposit is quite thick .

and different to the original salt we stirred the mixture for a few minutes .

and heated up to around 80 degrees C then allowed it to cool right down to .

nearly zero degrees in order to precipitate as much of the sodium .

chloride salt as possible on chilling for a few hours the salt fell to the .

bottom of the beaker leaving the clear solution so we set up for vacuum .

filtration and removed the white salt from the liquid .

we allowed all the liquid to filter through and for the salt to become reasonably dry .

we ended up with covering 40 grams of sodium chloride as you can see here it's slightly damp .

but even so according to the stoichiometry of the reaction we would expect 47 grams to be produced .

in total so this is not bad at all .

so this is not bad at all .

so this is not bad at all .

so this is not bad at all .

so this is not bad at all .

our filtrate is slightly yellow due to our filter not being totally clean .

however it tells us that we've got a lot of hypophosphorus acid as .

hypophosphite and hydrogen ions in this solution so we transferred this into a .

250 ml flask to see if we could distill of some of the water we added a small .

magnetic stirred bar so that we could stir to prevent the mixture from bumping .

and then used a hot plate to heat the mixture with a .

simple distillation app with a setup .

and then used a hot plate to heat the mixture with a simple distillation app with a setup .

we also used a vacuum pump to help drive off the water at a lower temperature .

we know that hypophosphorus acid decomposes temperatures higher than about 100 degrees .

c to form explosive and toxic phosphine gas so we wanted to be very careful about this .

soon we saw some condensation appearing .

and we insulated the flask using some aluminium foil to make the distillation more efficient .

and we insulated the flask using some aluminium foil to make the distillation more efficient .

Despite all these measures the distillation of water was incredibly .

slow and after an hour we had only managed to obtain around 10 mils of .

water distilled.

At this point we noticed a white precipitate, presumably more sodium .

chloride forming in the boiling flask, so we allowed the mixture to cool at this .

point and chilled it down again to zero degrees.

Once again we filtered this on a vacuum and we noticed that the liquid was now actually .

quite viscous and syrupy.

We got a further four grams of sodium chloride from this filtration, so we .

figured that we must have a relatively strong hypophosphorus acid solution by .

now. And here's the filtrate. Exactly 100 grams .

in weight.

And the filtrate is now 100 grams in weight.

We started measuring 74 mils giving a density of 1.35. The pure acid has a .

literature density of 1.49, so this is looking good.

So let's first put it to the test by reducing some iodine. We placed a small .

amount in a beaker and added a spatula of solid iodine at room temperature.

I'd say that worked pretty well. Maybe a bit too well.

Let's now see if the acid can be decomposed by heat. This will also tell .

us how safe it is to boil a reflux. We heated a small amount in a beaker on a .

hot plate. First we got some condensation.

Then very slight boiling. Then tiny explosion.

So we've definitely got some good stuff here, and we'll have a go in a future .

video at using it to reduce an alcohol.

In the meantime we'll leave you with our final experiment, evaporating the liquid .

to dryness on a glass petri dish. Enjoy.

The hot plate is only at about 150 degrees C, so this is a good warning about .

the reactivity of this compound. Huge clouds of white phosphorus pentoxide are .

generated as the phosphine gas produced spontaneously combusts in air.

Stay tuned.

Closed Captioning by Kris Brandhagen. brandhagen.com .