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Author: Subject: OTC glacial acetic acid need help
Mush
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[*] posted on 31-3-2020 at 16:56


Acetic acid, Vinegar, Ammonia, Alum
J. & A. Churchill
London
1885

https://archive.org/details/aceticacidvinega00londrich/page/...
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clearly_not_atara
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[*] posted on 31-3-2020 at 17:48


I think sodium pyrosulfate could probably be used to dehydrate acetic acid, since we already know that attempts to dehydrate GAA with this reagent return the starting materials. At the same time, GAA should not attack bisulfate.

I imagine you want to start with reasonably concentrated acetic acid. One advantage of the method is that you could also use acetic acid contaminated with some acetate salts.

[Edited on 1-4-2020 by clearly_not_atara]




[Edited on 04-20-1969 by clearly_not_atara]
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dicyanin
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[*] posted on 1-4-2020 at 14:07


I have the same problem, where I live you can readily find 80% acetic acid on the shelves of the larger hardware stores, but glacial acetic acid can only be bought through a chemical supply house, which is more hasslesome and expensive.

I found this method in "Dick's Encyclopedia of Practical Receipts and Processes", a curious work that contains a lot of recipes for household products, but also pyrotechnics and simple chemicals. The book can be downloaded from the Internet Archive:
https://archive.org/details/encyclopediaofpr00dick/page/n9/m...

It basically describes a method of gently pouring concentrated sulfuric acid on powdered sodium acetate with adequate cooling, letting it digest for some time, then gently heating the mixture above the melting point of glacial acetic acid but under the melting pont of the formed sodium sulfate, and decanting.

Then a small quantity of calcium acetate is added until there is no further precipitation of calcium sulfate. After the latter settles it is decanted and used as is.

glacial acetic acid without distillation.png - 327kB




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dicyanin
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[*] posted on 1-4-2020 at 14:17


And here from the same book is a method for preparing glacial acetic acid from 80% acetic acid. (page 365)

The 80% acetic acid is simply dried over anhydrous sodium sulfate.


Quote: Originally posted by JJay  

Apparently in olden times they prepared glacial acetic acid by first distilling acetic acid from anhydrous calcium chloride and then again from anhydrous sodium acetate, further purifying it by fractional freezing.

It's been said elsewhere on this board that copper sulfate and magnesium sulfate can be used to dry acetic acid, but I haven't seen a good writeup on either.


This seems very similar to drying over sodium sulfate.

Also the CaCl2 method notes that a considerable amount of HCl is present in the acetic acid after the first distillation. I wonder on a sidenote, if anhydrous CaBr2 is used this would be a good way to prepare an anhydrous solution of HBr in acetic acid?

glacial acetic acid by concentration of 80 percent AA.png - 264kB

[Edited on 1-4-2020 by dicyanin]

[Edited on 1-4-2020 by dicyanin]




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[*] posted on 9-7-2020 at 12:48


This might be a dumb question, but I have GAA standing in the fridge at 6C and it is still in very liquid form. As it should freeze at 16C, should this be cause of not having crystallization points, or something else?

I would not consider the acid bunk because it is from a reputable supplier.
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Tsjerk
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[*] posted on 9-7-2020 at 13:51


Give it a good shake, but otherwise a very small amount of water can cause significant lowering of the freezing point.
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[*] posted on 9-7-2020 at 17:41


Quote: Originally posted by XeonTheMGPony  
FAILURE!

After siting for several weeks over calcium chloride I ended up with a viscus fuming fluid.

I loaded it into a 250ml flask and then attached a 300mm fractional column and started slow heating, during this I got white fuming from the vent.

I suspect I ended up with HCl and Calcium Acetate, I recovered some Acetic acid + water :(

So I would not recommend drying with CaCl


Is it possible that acetic acid can liberate HCL.im thinking not as this will mean that a weaker acid liberates a stronger one.usually it's the stronger acid/base liberates the weaker one but I'm not 100% certain about this.maybe it can happen.
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[*] posted on 10-7-2020 at 13:09


Quote: Originally posted by Tsjerk  
Give it a good shake, but otherwise a very small amount of water can cause significant lowering of the freezing point.


Now it went glace. I gave it a decent shake earlier on the day. I hope it's indicator of purity. :P
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