Greetings fellow nerds.
Time for another review of my current projects in the lab.
The biggest one right now as you know is making sodium by the alcohol catalyzed magnesium reduction approach.
In this we mix sodium hydroxide, magnesium metal, mineral oil and a tertiary alcohol and upon heating we get sodium.
In my previous lab notes video i had spent a lot of time refining the process and was eventually able to get 60% to 70% yield.
Unfortunately the sodium hydroxide damages the glassware
and this problem is present no matter how carefully i performed the experiments or how slowly i raised the temperature.
As a practical approach to making sodium this is an utter disaster because glassware is more expensive than the reagents.
At this point it was time to re-examine the problem carefully and understand why it occurs.
As said before, sodium hydroxide reacts with the silicon dioxide in glass to form sodium silicate, this destroys the glass.
This happens infinitesimally slowly at room temperature and increases in speed as the temperature rises.
It also doesn't happen in the solid state, you have to dissolve it in water or melt the sodium hydroxide before it will start reacting.
Now sodium hydroxide melts at 330 celsius.
My hotplate isn't being heated to that high but the damage is still occurring, even at much lower temperatures of 200 celsius.
Why is it happening? Eventually i realized the sodium hydroxide i was using already had water in it absorbed from the air.
It's not too much, maybe about five to ten percent.
But that's enough to lower the melting temperature.
That's why the glassware is being destroyed even at the much lower operating temperatures of the sodium production reaction.
I needed a way to dry the sodium hydroxide.
Before we go down that route though we should check back with our theory and ask the question if this is viable.
Would liquid sodium hydroxide or solid sodium hydroxide make a difference.
According to our current working theory, when we're making sodium, the reaction doesn't actually need liquid sodium hydroxide,
the actual mobile species that's doing the work is the sodium alkoxide, and that doesn't attack glass to any significant degree.
As long as the sodium alkoxide can move, the sodium hydroxide can remain solid.
With this in mind we can explore ways of drying our sodium hydroxide.
Now i tried simply heating up the sodium hydroxide in mineral oil to drive the water out but that failed miserably and destroyed the flasks.
We could heat the sodium hydroxide in a steel container up past 330 celsius to drive the water out that way
but this wouldn't be perfect and there would still be water left over.
Also, when it cools it will be a hard solid chunk of sodium hydroxide which is difficult to work with.
I finally reached the idea of destroying the water directly with sodium metal.
I know this sounds crazy, stupid as well as circular but hear me out.
If we destroy the water with sodium metal then all we produce is more sodium hydroxide,
if we use an excess of magnesium metal then we can recover the sodium used up through the sodium production reaction.
Overall, we're not wasting sodium metal.
So to do that experiment i got some sodium, added in sodium hydroxide, a bit of tertiary alcohol
and started ramping up the temperature very slowly until the sodium melted.
We needed the sodium molten so that it can directly react with the sodium hydroxide.
Then i let it run and observed hydrogen bubbling out as the sodium destroyed water in the sodium hydroxide.
What's good about this method is that if any of the sodium hydroxide begins melting, it quickly reacts with the sodium.
After several hours i checked the flask for damage and it still seemed good,
nothing sticking to the glass or clouding normally associated with the sodium hydroxide reacting with it.
So i ramped up the temperature further up to the usual operating temperature of the sodium production reaction.
After another several hours the flask was damaged as you can see here by that dark material sticking to the inside surface of the glass.
But interesting enough it only happened on just a few spots while the rest of the flask was fine.
This was a huge improvement over the previous reactions where the entire bottom surface of the flask was destroyed.
I think these are hot spots where the flask contacts the hot plate and is thus hot enough to start a reaction between the glass and the sodium hydroxide.
I think all i need to do is lower the operating temperature slightly to eliminate the hotspots but still be hot enough to run the reaction.
So i started another run and once again i heated mineral oil, sodium metal, alcohol and sodium hydroxide at a temperature just high enough to melt the sodium.
I let this run for several hours and then added in magnesium metal.
This time i ramped up the temperature slowly until hydrogen started coming out of the bubbler.
The hotplate temperature was about 250 celsius and the internal temperature of the mineral oil was about 200 celsius.
My previous experiments at this temperature destroyed the flask, but this time with sodium drying things looked a lot better.
As usual i let it run for three days and this time it looked like it had worked.
And even the flask looked good.
I ran the new sodium processing method i described earlier to separate out the magnesium oxide, recover the sodium and separate out the excess magnesium metal.
And here is the flask after processing.
It worked! The flask survived the reaction.
The minor damage to the flask was from previous chemistry.
So it took over a month, but we solved the glassware destruction problem of the alcohol catalyzed magnesium reduction approach to making sodium.
We basically have to predry the sodium hydroxide using a small amount of starter sodium metal
and run at a more modest internal temperature of 200 celsius rather than the 300 celsius its normally run at.
Interestingly enough, in previous runs where i tried to use 200 celsius without a sodium predry, the reaction proceeded extremely slowly.
I think this is because with a high water content the magnesium metal itself has to react away the water before it can proceed to make sodium.
However magnesium, being solid, takes much longer to destroy the water than sodium metal.
At higher temperatures though the magnesium becomes more reactive again and the reaction proceeds at an acceptable rate.
Another interesting point is that after processing i measured the yield of resulting sodium.
Now i originally added 10 grams to dry the sodium hydroxide and jumpstart the reaction.
So the actual yield is 22.2 grams rather than 32.2.
Nonetheless, 22.2 grams is a yield of 96%.
This is a massive jump from all previous experiments.
The reaction might even be quantitative with the shortfall entirely covered by the mass difference in the sodium hydroxide due to water contamination
as well as handling losses when performing the process.
Looking back it seems the destruction of glassware was far more detrimental than i had initially believed.
The contamination of sodium silicates and borates from the borosilicate glassware severely depleted the available sodium hydroxide.
I think another contributing factor to the losses was that the glassware destruction reaction is also a water generating reaction.
This causes an unmitigated chain reaction of glassware destruction and the water further consumes our product.
I didn't think we'd lose almost 30% but judging from this near quantitative reaction that seems to be the case.
An additional note is that the recovered magnesium from the dioxane boiling is quite high as well.
Now i didn't weigh it in this run or any of my previous runs, but just from a subjective view i appears there is more of it.
I think the reaction is much more efficient now that we've eliminated a massive side product pathway.
It might be prudent in my next experiments to start reducing the magnesium used.
So far i've been using a molar excess but if the reaction is this efficient, we might still get excellent yield just from a molar equivalent.
Overall this has been a big breakthrough.
So using sodium metal drying and jumpstarting not only protects the glassware it also lets us speed up our reaction,
use lower operating temperatures and massively increase our efficiency as well as our yield up to near quantitative levels.
You know after the lab gods kept destroying us with failures, they might have given us this quadruple win out of pity.
Of course such a win comes at a price.
We have the rather small problem of getting an initial charge of sodium.
Without a sodium predry I don't know a way of not destroying the glassware.
The most straightforward way to get our initial charge of sodium is to first make some using the thermochemical dioxane process.
But i'll see if i can find a sodium alternative.
Maybe there is another approach to drying sodium hydroxide or protecting the glassware.
But even if never find a better way, getting the initial sodium charge from the thermochemical dioxane process isn't all that bad.
And if an amateur absolutely can't use that method, then the sacrifice of a single flask by the direct heating approach might be acceptable.
Once you have your initial charge of sodium you can just keep making more sodium and feeding forward to jumpstart your succeeding runs.
Now i'm still going to give myself another month or two to find a way to start up the reaction without sodium or destroying the glassware.
But on the whole, i think we're done.
We now have a viable process to make sodium by the alcohol catalyzed magnesium reduction approach
and the costs are relatively low now that we're not consuming glassware with every run.
I'm now certain I'll have the final how-to video ready in a month or two depending on whether i can find a way to start the reaction without using sodium or consuming glassware.
Thanks for watching.
Destroying almost a dozen flasks now this research has been pretty costly.
Not as costly as pyrimethamine but not cheap either.
So special thanks to my patreon supporters who fund these videos and make this possible.
If anyone else would like to contribute i would really appreciate it.
Your donation is how amazing science like this gets done.