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Author: Subject: Glacial acetic acid...
bbartlog
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 Quote: What would be the best way to produce AcOH from EtOH in an electrochemical cell?

This is touched on briefly on pp68-69 of this book: http://library.sciencemadness.org/library/books/the_manufact...
Dilute sulfuric acid in ethanol, platinum electrodes. There's another earlier book (Kolbe?) that I think also discusses the topic.
Efficiency-wise I think this compares unfavorably to other methods, but I suppose that if you started with relatively anhydrous ethanol it *would* have the advantage that separating your acetic acid from the solution might be easier. Or it might not; it seems like the conditions might be right for a lot of your acetic acid to be esterified to ethyl acetate, and then you'd be boiling that off first.
Sedit
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One of the methods I was using was the Mn(IV)persulfate cell just like the one in the Benzaldahyde thread just in a different concentration and time frame in an attempt to proceed all the way to the acid.

Thanks for mentioning Ethylacetate because quite honestly the thought of its formation until now just Wizzed right on by my head without a thought. Still under dilute condition of acid I don't feel its formation should be to problematic.

Iv been trying the whole time using Pb Electrods BTW for all those who where woundering.

Now I know Isopropyl acetate will decompose on contact with stainless steel so perhaps there use as an electrod here would aid slightly in the prevention of esterfication? Even if the primary product of Ethylacetate was formed im sure theres something I could do to crack this and even worst case senerio I could find a means of using a basic media in the cell to produce NaOAc in bulk and proceed from there but I really hate the idea of using H2SO4 to make my GAA because I have wasted more then enough in the past on this and yern for a better means.

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"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
Runningbear
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Here is the patent on the production of acetic acid from ethanol using electroysis in case anyone is interested.

http://journal.uii.ac.id/index.php/jurnal-teknoin/article/vi...

Sedit
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I just ran a rather quick and dirty experiment to test the viability of DCM solvent extraction method for Acetic acid and first round looks promising.

All I did was add sulfuric acid to Sodium acetate and then mixed in DCM and stirred. After a while there was a clean seperation of crappy slush on the bottom and yellowish DCM on top. I seperated the DCM which was simple since the bottom layer was pretty solid and evaporated the DCM.

About 25% of the recovered DCM was left behind as Glacial acetic acid. Right towards the end the DCM begun to look cloudy and a white precipitate started to form. After all the DCM was gone the entire liquid became immobile and turned into a think slush which im pretty sure is Glacial acetic acid. This smells extremely strong and burns your eyes and nose from about 8 inches away.

I might just run a scaled up proper version of this this weekend because this seems much easier then trying to distill the mixture which yeilds rather low at times due to problems heating the mixture.

Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
Sedit
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Sad to say a large amount of my 1mol scale Glacial acetic acid experiment spilled . Luckly it was pretty solid so I was able to scrap a large amount of it up and contain it. I extracted it with acetone and evaporated a small amount of it and to my confusion I was left with a biphasic mixture with a smell that was different then GAA. I don't know what the oil was on the top but it does not matter. Im rerunning the experiment now.

For all those getting there Sodium acetate from 5% acetic acid... STOP... those instant heat packs are only about 5$and they yeild about 400 grams of the trihydrate. Im drying it now to see how much I get but a small test shows that the acetic acid created from it is much more pure then the crap made from vinegar. I will never boil down gallons of vin Knowledge is useless to useless people... "I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan Sedit International Hazard Posts: 1939 Registered: 23-11-2008 Member Is Offline Mood: Manic Expressive Sad to say a large amount of my 1mol scale Glacial acetic acid experiment spilled . Luckly it was pretty solid so I was able to scrap a large amount of it up and contain it. I extracted it with acetone and evaporated a small amount of it and to my confusion I was left with a biphasic mixture with a smell that was different then GAA. I don't know what the oil was on the top but it does not matter. Im rerunning the experiment now. For all those getting there Sodium acetate from 5% acetic acid... STOP... those instant heat packs are only about 5$ and they yeild about 400 grams of the trihydrate. Im drying it now to see how much I get but a small test shows that the acetic acid created from it is much more pure then the crap made from vinegar. I will never boil down gallons of vinegar again.

[Edited on 26-10-2010 by Sedit]

Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
entropy51
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 Quote: Originally posted by Sedit For all those getting there Sodium acetate from 5% acetic acid... STOP... those instant heat packs are only about 5\$ and they yeild about 400 grams of the trihydrate. Im drying it now to see how much I get but a small test shows that the acetic acid created from it is much more pure then the crap made from vinegar. I will never boil down gallons of vinegar again.
I agree with Sedit that there are better sources of NaOAC, including hot packs. In case these sources are not available to some members, however, I can recommend the following method for preparing non-crap NaOAc from vinegar. I have supplied the prep to others who found it useful, so here it is:

My prep is to pour 400 mL WHITE vinegar into a flask and add 13.3 gms NaOH while stirring. I then distill off about two thirds of the water. Then I add another 400 mL vinegar, 13.3 gm NaOH, distill off H2O and repeat. I continue until a total of 5 batches has been added. After the last distillation cool and crystals of NaOAc should form (gets hot when crystals form). If not distill off some more H2O and cool again. Filter and dry the crystals, first in air, then in a dessicator. From the 5 batches I get over 200 gm of nice white crystals, over 90% yield. The rest is obviously in the filtrate and I usually add the filtrate to the next set of 5 batches. Sounds cumbersome but once you get it going, it becomes almost automatic and you can crank it out. I distill instead of just boiling so I know how much water I've removed and to avoid vinegar smell, which can get annoying if you're in large scale production.
Random
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Ca(OAc)2(aq) (excess) + CuSO4(aq) ---> CaSO4(s) + Cu(OAc)2 (Aq)
boil down copper acetate solution

Cu(OAc)2(s) (maybe excess) + HCl(aq) -→ CuCl2 + HOAc

CuCl2(aq) + Cu(s) + HOAc(aq) -→ CuCl(s) + HOAc (l)

Freeze acetic to concentrate it even more (16 degrees celsius)?

This is my route which now I "discovered". Just, would it actually work to make glacial acetic acid which will freeze at 16 degrees celsius?

Or just I can add Ca(OAc)2 to HCl in excess and then filter to make glacial acetic?

[Edited on 8-11-2010 by Random]

[Edited on 8-11-2010 by Random]
Sedit
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? Um.... what?

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Random
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Well, the stronger acid should put out the weaker acid from the salt.
Sedit
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True but when was the last time you seen a 100% HCl solution?

I tried using HCl before on NaAc and no matter what people say there was only little conversion of the NaAc to AcOH. What this is I do not know.

Knowledge is useless to useless people...

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What about freeze distillation of white vinegar?

I've done it, pour 1,5 liters of vinegar to a 2L soda bottle and stick that at the freezer for 24 hours, then put it upside down, make a hole in the ice so melting liquid can scape from the air bubble, hold this on a funnel over a beaker and wait for the more concentrated acetic to melt down to the beaker. Repeat this a few times with the concentrate and you should obtain a more concentrate acid, then salt out, distill, or what ever.

I've took aliquots of vinegar to know the conc. of the "distilled" vinegar as it was melting, but with out a propper burette, indicator and patron solution, I can not determine the optimal volume of melt to obtain each time.

Hope this all is usefull. Check this out: http://www.alchemywebsite.com/distillation_of_vinegar.html

You'll obtain a vinegar strong enough to work the way of the acetate!
bbartlog
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I've mixed sodium acetate and hydrochloric acid with some success (meaning, I got a fairly concentrated acetic acid). But of course it wasn't glacial, and fractional distillation only got part of it from something like 40% to 56% as I recall.
Anyway, I don't understand the purpose of the copper in your proposed method. You could just add HCl to the calcium acetate and be in pretty much the same place as you'd be with the CuCl + acetic acid; I mean, I guess CuCl can be filtered out while CaCl2 is soluble, but I think you're overcomplicating things in an attempt to avoid distillation of any kind?
Also, I'm not sure how fast the reaction Cu+CuCl2 -> 2CuCl proceeds without the presence of some extra HCl. With copper pennies it takes a little while, at boiling temperatures, even with fairly concentrated HCl + CuCl2 solution. Now if you have very fine copper powder this may not be an objection, but it's something to consider.

Sedit
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Im working on the DCM extraction of AcOH as we speak but being short of DCM im in the middle of distilling some right now. I promise everyone that this will make GAA much simpler then all other methods because I have been running the numbers and it appears that the formed sodium sulfate from Sodium bisulfate + Sodium acetate trihydrate will trap all the water in the form of the decahydrate of sodium sulfate. Seeing as drying agents are rarely complete it will be of no issue to just dry the DCM with MgSO4 which can then be filtered off. The DCM will evaporate at a very low temperature for recovery and what is left is Glacial acetic acid. I have already seen this produce crystalized Glacial acetic acid on test tube scales with ease.

Preliminary test have been promising to say the lest. The main factors are letting it age for a couple days to ensure total reaction and competent function of the drying agent. Plus filtering should be done below 30 degrees C else the sulfate will begin to lose water.

Knowledge is useless to useless people...

"I see a lot of patterns in our behavior as a nation that parallel a lot of other historical processes. The fall of Rome, the fall of Germany — the fall of the ruling country, the people who think they can do whatever they want without anybody else's consent. I've seen this story before."~Maynard James Keenan
cnidocyte
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 Quote: Originally posted by Hexagon What about freeze distillation of white vinegar? I've done it, pour 1,5 liters of vinegar to a 2L soda bottle and stick that at the freezer for 24 hours, then put it upside down, make a hole in the ice so melting liquid can scape from the air bubble, hold this on a funnel over a beaker and wait for the more concentrated acetic to melt down to the beaker. Repeat this a few times with the concentrate and you should obtain a more concentrate acid, then salt out, distill, or what ever.

Why would the acetic acid melt before the water? I tried freeze concentrating acetic acid in vinegar by putting a pot of white vinegar in the freezer and just filtering out the ice as it forms. Don't think it worked to well though because I repeated the process at least 3 times but the remaining liquid still reeked of vinegar.
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 Sciencemadness Discussion Board » Fundamentals » Chemistry in General » Glacial acetic acid... Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues