RogueRose
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Sodium Acetate decomposition gave a black liquid that turns flaky grey
I've been trying to figure out exactly how my sodium acetate decomposed as it was on a stove burner on medium and it is listed to deompose at 1620F
which I have a very difficult time believing this temperature was reached, even any temp above 1200F would be extremely doubtful.
Anyway a black liquid formed that seemed repellent from any of the dried (still hot) sodium acetate, as it wouldn't really stick to it at all while
the black stuff was in liquid form. When it cooled it left VERY fluffy grey "flows" that were smooth and glossy on the top and when broken were very
flaky with lots of tiny air pockets.
I've looked at possible reactions for decomposition of sodium acetate and there seems to be some opposing ideas. One says it releases acetic
anhydride and the other states acetic acid - the anhydride may turn to the acid when it contacts moisture in the air. As far as the sodium compound,
some suggest Na2O and others NaOH.
When I dissolved some of the grey material in water it did dissolve easily and turned a light brown color (fair excess of water, about 10ml to .2g
grey material).
I did not notice much smell from the hot substance, though I did still smell a strong vinegar smell when I broke the surface of the dried sodium
acetate (to reveal the black liquid). Others have suggested a mix of CH4, CO and CO2 being released by decomp, possibly in addition to an acetic
acid/hydride? Others have said possibly acetone, though I did not notice that smell in the slightest and it is a very noticeable odor.
Has anyone else tried this? I used a stainless vessel and would be afraid to try this in a glass container for so many reasons, possibly etching with
hot Na2O/NaOH and then it would be impossible to get out w/o breaking the glass (it's near impossible with a metal pot/vessel).
I will say that when I made the acetate, I used vinegar and baking soda, reduced by 80%, filtered 2x through activated carbon (to remove browning
color in solution). I had an excess of about 5-8% vinegar to ensure an acidic solution while evaporating and no remaining bicarb.
I must say that the only time I've seem similar results is when purifying K2CO3 from wood ash. I filtered same as above and got a clear solution,
boiled down and when it turned liquid at very high temp (~1636F - near same temp as sodium acetate) and was the same color as the acetate. A black
liquid that dried a very solid/dense grey. Upon dissolving and filtering it make a brown slightly grey solution, filtering with AC cleared this up
and final evaporation gave "pure" white crystals.
[Edited on 2-6-2019 by RogueRose]
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XeonTheMGPony
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there is a a lot of garbage left over when doing it that way, best to recrystallize in methanol, filter, then fuse if you want a fairly pure product
with out organic char
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walruslover69
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A lot of it was probably sugars from the vinegar decomposing and caramelizing. You could do a titration to see how much by weight is actually sodium
acetate. One cool thing is that you probably generated some carbon nano particles, mainly graphene quantum dots. They can be formed from the thermal
decomposition of things like sugars and citric acid. When purified they fluoresce nicely but the purification usually involves a membrane or dialysis.
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fusso
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Quote: Originally posted by walruslover69  | | A lot of it was probably sugars from the vinegar decomposing and caramelizing. You could do a titration to see how much by weight is actually sodium
acetate. One cool thing is that you probably generated some carbon nano particles, mainly graphene quantum dots. They can be formed from the thermal
decomposition of things like sugars and citric acid. When purified they fluoresce nicely but the purification usually involves a membrane or dialysis.
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That looks like a nice way to synthesise them!
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walruslover69
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ive tried it by just heating a couple grams of citric acid on a hot plate for a couple minutes until its a very dark brown and then neutralized it
with a NaOH solution. The Naoh created functionalized OH groups on the ends of the graphene sheet solubilizing them. I never did any purification, but
i was able to detect a small amount of fluorescence around 500nm on a spectro-vis. It was pretty cool for a 15 minutes synthesis.
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