An explanation for my shiney sodium!

[jdurg]

I think I FINALLY figured out why some of my sodium is bright and shiney and why some of it has turned into the typical gray sodium oxide/hydroxide color.

 

 

When I was first starting out my element collection, I didn't really pay much attention to the different densities of the elements. So when I saw some sodium metal for sale on E-Bay I decided to get two ounces of it. Little did I realize that 2-ounces is a helluva lot of sodium metal. Even worse, when the sodium arrived via UPS it wasn't under oil. It was just sealed in a water/air-proof baggy. Suffice it to say, it was HEAVILY oxidized. I had some spare mineral oil from a different element I had bought and a spare vial as well. So I took the sodium and put it in the vial and snapped the lid on. It has remained there ever since. However, I had a lot of sodium left over so I had to put it in another jar. This time I used a canning jar but I was out of oil. I went on E-Bay and got some dirt cheap oil from some soap maker. (A fact that I just now remembered). The oil arrived and I poured it in the canning jar with the sodium. Then I just let it be. A few months later, I was writing an article on sodium and decided to take some out. As can be seen on the picture above, the two different storage containers produced two vastly different types of sodium.

 

In the picture, the sodium photographed is that from my soap-making oil jar. The other sodium didn't change at all and looks like typical sodium. The other sodium became bright and shiney, and turned reddish upon removal of the oil. Also, there is this yellow 'gunk' around the sodium and a nasty amine-like fish odor to it. It was driving me crazy trying to figure out how that sodium retained its bright, metallic luster while all other sodium I've seen has turned the typical dull gray. Again, I just ignored it and continued on my ways.

 

Today I decided to photograph that metallic sodium for posterity reasons. I opened the jar and noticed that it still had a strong fish odor to it, but the yellow 'gunk' all settled down to the bottom of the jar. I took some tweezers to pull a piece of metallic sodium out, and it wouldn't budge! I then realized that all the yellow gunk had solidified and the top of it was a clear oil. It then clicked; the yellow 'gunk' is soap and the clear oil is glycerin. I had simply made soap! I remembered that I had bought the oil off of someone who sells soap making stuff, but it wasn't labelled as a soap making oil. It was simply listed as 'mineral oil'. The fish odor has probably come about as the result of some organic contamination. The sodium turned metallic and shiney because the outer oxide/hydroxide layer had saponified the oil creating the yellow soap and the clear glycerine. The soap/glycerine then adhered to the metal surface and prevented further oxidation. As a result, the sodium stayed nice and shiney. Finally, I've figured out why the metal didn't grow duller, and instead became very lustrous. Now if only I could conclusively determine where that nasty smell is coming from.

[Gilded]

Lol, quite a surprise indeed. ) Too bad you can't get sodium from eBay these days.

[jdurg]

Based on the odor and the color of the 'soap' and 'gunk', I'd have to say the offending smell is coming from liberated Pyridine. Blech. Nasty smelling crap. I only wish I had access to a GC/MS because then I could fully analyze this stuff.

[budullewraagh]

you can make pyridine with sodium and glycerol???????

 

really, where did you get the idea of pyridine from?

[jdurg]

I got the idea of pyridine from the yellow color of the crap and the fish-like odor. I did a search on the web for fish-like odor and yellow, and pyridine kept coming up. The pyridine did not come from the glycerol. What is more likely is that the oil which I used had some pyridine, or pyridine-like, structure in the triglycerol chain. As the sodium saponified the oil, it cut loose the pyridine (or pyridine like compound). There's another possibility that it could be methylamine, but I highly doubt it. The best way to find out would be to have access to a GC/MS, but I don't have that at my disposal.

[budullewraagh]

pyridine is incredibly difficult to find tho, considering it's one of the most closely watched chems

[jdurg]

What does that have to do with the possibility of the oil having been contaminated and releasing the pyridine upon reaction with the sodium?

[budullewraagh]

Na doesnt react with anything to make pyridine..... as far as i know...

[jdurg]

I know that. But what's preventing the pyridine from being a part of the triglyceride?

[budullewraagh]

um...ok so we have glycerol. youre saying that pyridine esterfied with it or something??

[jdurg]

What I think happened is that the sodium was originally put in with a strong coating of Na2O/NaOH on the surface. As a result, any triglycerides in the oil would have been severed leaving glycerine and the triglyceride 'tails'. So I'm thinking along a few lines here. It is possible that a pyridine ring was a portion of some of the triglyceride 'tails' and upon being severed from the glycerine backbone, the ring came free with some alkane chains attached. (Or as the free pyridine ring itself). The fact that there is an amine compound in there cannot be questioned. The smell is quite fish-like and the color is a distinctive yellow. The original oil does not have any fish-odor to it at all, nor does it have any color. Therefore, the only logical place for this smell and coloring to come from was something chemically bound within the oil. This is why I desperately want to have access to a GC/MS to get confirmation on what it is. Perhaps I'll have to ask around and see if anybody has GC/MS access and could run a sample for me. Maybe I can talk to my old organic chemistry professor? Hmmm.......

[budullewraagh]

that would be really, really weird. i think there was some odd impurity

[jdurg]

Yeah, that's why I'd like to send a sample of the pure oil and then the 'after' oil. The fact that the sodium went from a dull gray color to a VERY lustrous metallic color tells me that the oxide/hydroxide/peroxide? on it definitely reacted with the oil letting loose that amine/pyridine. The smell of decaying fish is unmistakeable, and it really has a yellow color. The junk at the bottom seems to be a soap of some sorts because it is all lumped together. I'll probably try putting some of the yellow gunk in water this coming weekend to see if it will create a lather or what. I'll probably e-mail my old o-chem professor and see if he'd be willing to run the sodium oil through a GC/MS along with some analysis of my starting oil. I'd really like to know what went on there. Still, having bright, metallic sodium metal is kind of neat.

[budullewraagh]

well, sodium likes to make the peroxide...perhaps it reduced then acted as a base?

[jdurg]

Here's another possibility that I can't believe I completely forgot about! When thinking about it, it's probably more likely than a pyridine like compound simply due to stereoscopic constraints. What if the ends of the triglyceride chains were quaternary amines? The presence of the all the OH from the sodium metal could have cleaved both ends of the chain forming the soap, the glycerol, and trimethylamine which REALLY smells like rotted fish. That could be very possible too. ARRRGGGHHH. I really wish I could figure this out. lol.

[budullewraagh]

trimethylamine. eek