hikerjohnson
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Posts: 3
Registered: 11-2-2013
Location: New England
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Propionic Acid via Haloform
Hi folks, finally had a chance over the last couple of weeks to clean up the leftovers from a 4-gallon haloform reaction to make some chloroform for
stock.
In short, something went sideways, but I don't know what.
Longer story; close to a year or more ago, I decided to mimic NurdRage and use MEK and bleach to make chloroform, and then go after the propionic acid
byproduct.
The initial reaction went very well, and I was able to separate out the chloroform, no problem.
After that, several liters of HCl went in, and then life caught up with me, and the raw dilute acid sat in a bucket in the basement for at least a
year.
Come to the present, I find time again, and spend a few days distilling the dilute Propionic acid azeotrope off the salt brine.
To the dilute acid, I added Sodium Bicarbonate until no more fizzing occurred, and I dried the liquid down to a very tough, light tan crystal of,
presumably, Sodium Proprionate. I baked this to be as dry as possible for several hours at about 300F. Smelled a lot like fresh bread.
To this I added, slowly, concentrated (98%) sulfuric, about 700mL in total to get the vast majority of the solid to dissolve.
I put this in a simple distillation setup, and commenced heating. This is where things got weird. From ambient up to maybe 150C at the stillhead, I
got a little bit of clear liquid, maybe 50mL, and continuous light white acrid fumes, no sign of condensing for those. After this, the still head
temperature rose and settled at 280C, where a steady drip of clear liquid came over. I ended up cutting the heat last night about 2/3 of the way
through the 700-ish mL of liquid, which during distillation had cleared up from brown to light yellow.
Now, 280C doesn't even remotely line up with propionic, dry or wet. Nor does it align with sulfuric.
Best I can guess is that the propionic acid degraded in long term storage into something else.
Apologies for non-technical terminology, I am an engineer by training, and enjoy playing chemist in my spare time.
Any thoughts as to what I collected?
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Fery
International Hazard
Posts: 1015
Registered: 27-8-2019
Location: Czechoslovakia
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Propionic acid is stable, it does not degrade. The same their salts. How much of dry sodium propionate did you obtain? Could you buy sodium or
potassium propionate as a food preservative (E281 or E283) and repeat the experiment?
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hikerjohnson
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Posts: 3
Registered: 11-2-2013
Location: New England
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Fery, I may do this, it is a good suggestion. In the meantime, here are a couple of photos of the undistilled material, which turned to a white solid
that is similar looking to napthalene. The distillate is clear, and remarkably dense.
I am unsure if I will finish distilling this, or just neutralize and dispose of it.
 
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