Sciencemadness Discussion Board - Glacial acetic acid...

Glacial acetic acid...

evil_lurker - 7-7-2005 at 15:41

I'm working on a way to get as close to pure acetic acid without having to order it and pay those outrageous hazmat fees.

I know that you can reduce vinegar down to sodium acetate, and mix it with 98% sulfuric acid and get a finished product close to glacial.

However, that is another acid that is hard to come by in high purity, again without paying those ridiculous hazmat fees. I know I can get the stuff as drain opener, but most brands are only 93% and/or contain numerous buffers that would hinder the process.

I was thinking that I could take the sodium acetate and mix it with some store bought concentrated hydrochloric acid then filter out the salt.

I realize that the potential end product will be far from glacial, but mainly I want to know if the NaOAc will react with the HCI.

Is this doable?

[Edited on 7-7-2005 by evil_lurker]

Twospoons - 7-7-2005 at 16:10

In New Zealand glacial acetic is available OTC from pharmacies. Where are you?

Magpie - 7-7-2005 at 16:20

Yes, it is doable with HCl. I bought some muriatic acid specifically for that purpose. Did you search and read the postings? I believe this is also covered under Muspratt IIRC.

Simon - 7-7-2005 at 16:46

Some photographic shops sell acetic acid at, IIRC, ~900g/L as stop bath. (NB some shops also sell something called "odourless stop". Obviously this isn't concentrated acetic acid

)

kclo4 - 7-7-2005 at 17:42

you could buy some NaHSO4 (sodium bisulfate) and add it to your sodium acetate and distill of the acetic acid. you can get NaHSO4 from Walmart as PH down in the pool supplies
i don't know how well it would work but because i have not ever tried it but i plan to in the future when i get a distiller. does any one know how good the yields would be?

neutrino - 7-7-2005 at 17:49

If you live near a pool store, you can probably get sodium bisulfate (NaHSO4

cheaply. Reflux with sodium acetate and you get GAA:

NaHSO4 + NaC2H3O2 <--> Na2SO4 + C2H4O2

This equilibrium is driven to the right by your acetic acid boiling off. This was described in another thread here somewhere.

edit: I posted at the same time as kclo4. These subscipts take too long...

[Edited on 8-7-2005 by neutrino]

chromium - 7-7-2005 at 22:07

I do not belive that 93% sulfuric does not give glacial acetic acid when sodium acetate is distilled with it. I think that buffers too cannot stop it doing so. You should at least try.

Another way is to make it from some vinegar by freesing. Does anyone know what temperature is needed to freese it out from 30% or 10% acetic acid? Is it possible at all? ( i have tried this @ -10C with no results )

Magpie - 8-7-2005 at 09:39

Check out the "Acetic acid/ sodium hydroxide" thread. Most of this has already been hashed out there.

jimwig - 8-7-2005 at 12:51

this is so obvious but i had to say it

i went to a photo supply specialist and there on the shelf were $20 gallons of glacial acetic acid.

does New Zealand have these. it is a photo chemical used to make stop bath.

which is used in goth film and paper chemistry processing to stop the action of the alkaline developers.

try these places.

btw NZ is supposed one of the most beautiful places on Earth - z'that so?

jim

16MillionEyes - 20-5-2007 at 10:47

And where do you live? I'd like to know what store you can find this from.

evil_lurker - 20-5-2007 at 12:09

Well its been a long time since 2005 and I've significantly broadened my horizons.

That said, this is the place to get your glacial acetic acid:

www.hvchemical.com

organometallic - 22-7-2007 at 11:02

Is it not possible to fractionally distill or vacuum distill acetic acid from vinegar?

Magpie - 22-7-2007 at 13:04

Here's a long thread on the topic:

http://www.sciencemadness.org/talk/viewthread.php?tid=2194&a...

evil_lurker - 22-7-2007 at 13:06

No.

The acetic acid will form an azeotrope that is just about impossible to break.

The only practical means would be to neutralize the acid with a salt, boil off the water, and add to another acid such as sulfuric and distill.

12AX7 - 22-7-2007 at 14:12

Isn't the azeotrope at like, 4%, but after that, the seperation between H2O and AcOH is really bad?

Tim

chromium - 22-7-2007 at 14:43

As far as i know there is no azeotrope with acetic acid and water, just evaporation rates are almost equal. It'is quite possible to make GAA by distillation but you need good hempel column and have to collect maybe only one drop of distillate per minute - or great part of acetic acid comes over along with H2O.

It is even possible to just boil out water from acetic acid but almost all acetic acid evaporates along with it. Long time ago i did some experiments with 30% acetic acid. I boiled it until volume decreased to about 1/10th of original volume. IIRC titration showed that residue was 58% AA.

Acetic acid is good example that rule of thumb which tells that remarakble differences in boiling points ensure easy separation, does not always hold.

16MillionEyes - 25-7-2007 at 08:36

I don't remember well where I read this from but you can heat sodium acetate to decomposition giving off acetic acid. Never tried it nor I know if it works for sure. I don't know how this reaction actually works or what byproducts it gives.
The following section from an MSDS also seems to suggest this reaction does occur:
"Unusual Fire or Explosion Hazard:
THERMAL DECOMPOSITION MAY PRODUCE ACRID SMOKE AND IRRITATING FUMES." (http://www.sefsc.noaa.gov/HTMLdocs/SodiumAcetate.htm)
Also, in this other MSDS clearly states the production of the acetic acid (http://www.ambion.com/techlib/msds/msds_9740.pdf)

Perhaps the reaction goes as follows:
2NaCH3COO ---> CH3COOH + H2O + 2C + Na2O
Any ideas?

[Edited on 25-7-2007 by __________]

[Edited on 25-7-2007 by __________]

chromium - 25-7-2007 at 12:32

Quote:

Originally posted by __________
I don't remember well where I read this from but you can heat sodium acetate to decomposition giving off acetic acid. Never tried it nor I know if it works for sure. I don't know how this reaction actually works or what byproducts it gives.
The following section from an MSDS also seems to suggest this reaction does occur:
"Unusual Fire or Explosion Hazard:
THERMAL DECOMPOSITION MAY PRODUCE ACRID SMOKE AND IRRITATING FUMES." (http://www.sefsc.noaa.gov/HTMLdocs/SodiumAcetate.htm)
Also, in this other MSDS clearly states the production of the acetic acid (http://www.ambion.com/techlib/msds/msds_9740.pdf)

Perhaps the reaction goes as follows:
2NaCH3COO ---> CH3COOH + H2O + 2C + Na2O
Any ideas?

[Edited on 25-7-2007 by __________]

[Edited on 25-7-2007 by __________]

This does not work. Acetates yield acetone on pyrolysis but if i recall correctly sodium acetate complexes with acetic acid and it is somehaw possible to precipitate this complex. It decomposes on mild heating giving some acetic acid.

chemrox - 25-7-2007 at 14:31

I just posted this in another thread. I shan't retype the citation. For homebake I'd go the benzene/butyl acetate route or maybe try CuSO4 by itself.

[Edited on 25-7-2007 by chemrox]

acetic.jpg - 123kB

16MillionEyes - 25-7-2007 at 19:04

So how would the chemical equation for that reaction go? Besides, why would the last MSDS list "acetic acid" as one of the decomposition products if it supposedly doesn't do it?

not_important - 25-7-2007 at 20:16

Thermal decomposition of acetates tends to be messy, especially if it is a hydrated salt.

Sodium acetate gives a mixture of stuff, including some acetic acid, methane, acetone, diacetyl, and others. Calcium acetate gives mostly acetone, but other products as well. Some of the heavy metal acetates will yield a fair amount of acetic acid or (apparently, haven't tried) acetic anhydride.

Just being listed as a decomposition product doesn't mean you'll get a decent yield, or that the products will be easy to separate in pure form.

16MillionEyes - 26-7-2007 at 18:26

Never said they would but saying it will be a low yield is different to "it does not work".

Pixicious - 27-3-2008 at 06:04

Here is a method if you have access to Sulphuric Acid.

NH4Cl + NaOH -> NaCl + NH3 + H2O

You have your salt if you boil away the water.

H2SO4 + NaCl -> Na2SO4 + HCl

Mix the HCl gas with water. Put it aside, you can use it later.

CH3COOH + NaHCO3 -> CO2 + H2O + CH3COONa

Add an slight excess of Vinegar. Boil to but not beyond 320oC. The Sodium Acetate will decompose. The remaining solution if using Tesco's Value Vinegar is a guey mess (Ammonia Caramel) and a white powder. Cook in an oven at 103oC, chop and grind the powder.

HCl + CH3COONa -> CH3COOH + NaCl + H2O

Use an excess of Sodium Acetate, filter and dry distill.

I haven't tried the last step, I still have Sodium Acetate sitting in my room. I haven't had any time to make any new Sulphuric acid.

MagicJigPipe - 27-3-2008 at 07:51

I have some excess sodium acetate so I'm going to get some bisulfate today and try that method. Many pictures will hopefully insue. Will this thread be the right place to post a "write-up"?

Also, in my area, 90% of the photographers and photographic stores that I called just straight up said "No!" when I asked for GAA. The other ones gave an explanation of why I shouldn't use it and/or referred me to a place that had 28% acetic acid for an outrageous price.

"You want what!??", "You don't want to use that, it stinks up the whole place and it burns your skin and nostrils.", "Nobody uses that anymore".

A couple didn't even know what it was.

This chemophobic society is truly pathetic.

len1 - 27-3-2008 at 08:10

Ive tried this, its not really worthwhile because

1) vinegar contains very little CH3COOH, theres a lot of water to be boiled
2) It contains other rubbish such as sugar, which yield acrolein and other unpleasant stuff which foul when you distill the acetic off H2SO4. The sugar i very hard to be rid off

Using HCl instead of H2SO4 will lead to a huge Cl- content

Using NaHSO4 will lead to excessive decompoition of the acetate and other products

Haloform with acetone is far more economical

Jor - 27-3-2008 at 11:16

Magic, If HazMat is such a problem, try to find a supplier that is near you, so you can pick up a large amount at once.

Maybe the supplier I gave you for potassium iodide could send it to you, with no HazMat. Did you buy your KI there?

MagicJigPipe - 27-3-2008 at 16:18

len1, maybe you know. What do they mean by "Distilled White Vinegar". Surely if they distill the vinegar there can't be any sugars. There's a thread called "Sodium Acetate Discoloration" where someone mentions what the impurities might be.

len1 - 27-3-2008 at 16:28

I have not seen distilled white vinegar here. My experiments were with white vinegar of course (since the brown variety is obviously high in impurities. It does sound like its worth investigating.

It is of course possible to distill white vinegar yourself - that should eliminate sugars to a degree - but imagine distilling 2L, then reacting with baking soda (which also contains sugars) then boiling it down, then reacting with H2SO4 all for just 20gram or so of GAA. I still think acetone, or oxidation of meths is a better way.

microcosmicus - 27-3-2008 at 16:35

Quote:

baking soda (which also contains sugars)

Huh? Every time I have encountered baking soda, it has
been NaHCO3. Maybe it contained some impurities like
K or Mg or Ca instead of Na, but most definitely no
organic stuff.

len1 - 27-3-2008 at 16:57

I have been calcining NaHCO3 recently to turn it to Na2CO3, and found solutions of the latter to always have a light brown colour. I presume from organics decomposed during calcining.

MagicJigPipe - 27-3-2008 at 18:58

What kind of baking soda do you use len1? I buy USP baking soda from the grocery store and I have never had brown solutions from it. It's always a very pure white color even when I heat it to Na2CO3 and dissolve the solutions are very clear.

Also, distilled white vinegar should be in your local grocery store in the condiments section. Even the generic (Kroger) brand is distilled where I live.

The only problem is that NaAc derived from this distilled vinegar turns brown upon heating and it's solutions are brown as well. That doesn't really matter if you're making GAA though. It only takes a few hours to boil down the vinegar and I get huge pan fulls of NaAc every time.

Still, buying GAA is easier and if the price is low enough it should be done that way. It just so happens though, for me, doing it this way is MUCH cheaper because of HAZMAT fees and it's unavailability in my area.

S.C. Wack - 27-3-2008 at 21:10

"Distilled" refers to the alcohol (later denatured with ethyl acetate perhaps) used to make it, not the product. If it was, it wouldn't be vinegar anymore, it would just be dilute acetic acid.

Recrystallization and decolorization of boiled down some neutralized vinegar will eventually give a decent white product. Charring on adding sulfuric acid is a problem with CP acetate even, it must be added slowly and with good stirring which is very unpleasant if not done in a flask or in a hood. I've never tried bisulfate with acetate, but if someone should try, that would be an interesting report for posting here. I've made formic acid (and CO!) in this way in the past, I've since forgotten the patent number that I read this in.

len1 - 28-3-2008 at 17:30

Ive used two brands on NaHCO3 and they both produced various amount of charred organics when calcined. This was one of the reasons why a final steam distillation step was necessary in my benzaldehyde purification. I also have lab grade carbonate, but it costs about $40/500gms and I dont want to waste it on just purification.

The brands (MacKenzies is one) wont mean much to you as theyre Australian - but it does mean that the US chemical industry has outstripped ours, which prob still uses 19th century methods, like Leblanc. Do what I can theres no distilled vinegar at my local store - you guys in the US just have life too good

Still lets do the economics - vinegar cells for about $1.50/L, so for a 10L run (which would have to involve bucket chemistry rather than lab apparatus) youd get about 200gms GAA (including losses) - for $15 - thats $75/L not counting the acid and all the hassles with distillation (thanks to SC Wack for clarifying that - I had always thought white vinegar was meant as dilute AA) calcination, and redistillation fro H2SO4. Alcohol costs $2.50/L, acetone $10/L so the economics are clear

[Edited on 29-3-2008 by len1]

not_important - 28-3-2008 at 19:52

I just tried heatingbaking soda purchased at a local shop, no sign of charring when slowly heated to 500 C, although it did get agitated as it decomposes to the carbonate.

In the USA most sodium carbonate and bicarbonate come from the mining of nahcolite and trona, some other regions have deposits of one or the other. If there are no useful deposits of those, the Solvay or Hou processes. China uses Hou, Solvay, and mined trona in decreasing magnitude, Australia seems to be using Solvay although they may be switching over to Ou to eliminate the CaCl2 byproduct which has little demand there.

Solvay and Hou shouldn't be leaving organics in the bicarbonate, which normally is one of the purest chemicals produced on a large scale. Perhaps other members could perform the test, and see if we can localise this as well as determine the nature of the charring.

Your vinegar is expensive, that is at least thrice what I pay. And with no need to calcine the economics would be different in my case.

Isopropyl alcohol can be used to extract much of the coloured matter from the crude sodium acetate hydrate. An alternative is the dehydration of the hydrate by slowly added the powdered solid to refluxing alcohol-toluene and allowing the water azeotrope to distill off. Finish up by distilling the alcohol-toluene azeotrope and you have powdered anhydrous sodium acetate with the organics in toluene solution.

len1 - 28-3-2008 at 20:10

Ill post a few pics shortly just so that you can see what we Australians have to make do with

[Edited on 29-3-2008 by len1]

Na2CO3.JPG - 17kB

MagicJigPipe - 29-3-2008 at 04:21

Yes, vinegar here (distilled white, thanks for the info on that S.C. Wack, I always had a feeling they were referring to the alcohol used to make it and not the vinegar itself, otherwise there shouldn't be any brown products!) comes in gallon containers for about $1.50.

So, at that price and the price of H2SO4 it comes out to being a little bit cheaper than ordering GAA online for me. If I factored the isopropanol in it would be about the same because I can get anhydrous IPA for a few dollars a gallon, as well.

Now, if only my time and hard work was worth the remainder!

PS. Speaking of bulk alcohols, I also found a source of absolute EtOH for an EXCELLENT price. And the acetone is even cheaper so now the acetone/EtOH method seems like a good option now. Is there a thread covering it? I really did hit the jackpot with this solvent supplier!

[Edited on 29-3-2008 by MagicJigPipe]

not_important - 29-3-2008 at 04:58

Note that the IPA can be mostly recovered with simple distillation, so it's a lesser expense. Some sodium acetate is extracted by it, on a large scale that might be work recovering.

Calcium carbonate or hydroxide can be used in place of sodium carbonate or bicarbonate; this has the advantages that they are very cheap, and that calcium acetate seems to be bit less soluble in alcohol that the sodium salt. If you're using sulfuric acid to displace the acetate then the removal of some of the water by the CaSO4 can reduce the dehydration requirements - the monohydrate is quite acceptable.

By acetone I assume you mean via haloform reaction, which may be hiding in chloroform threads. Ethanol to acetate means more direct oxidation, the OCl(-) with nickel catalyst would seem to be a reasonable route there. Note that denatured ethanol is likely to contain methanol, giving formic acid mixed with the acetic.

Formatik - 30-3-2008 at 05:42

Quote:

Originally posted by evil_lurker
I'm working on a way to get as close to pure acetic acid without having to order it and pay those outrageous hazmat fees.

I know that you can reduce vinegar down to sodium acetate, and mix it with 98% sulfuric acid and get a finished product close to glacial.

Either that or you could heat and distill dry wood (sawdust). And then if you react the distillate with calcium hydroxide, calcium acetate results: Ca(OH)2 + 2 CH3COOH -> (CH3COO)2Ca + 2 H2O. Then get the acid by reaction with sulfuric acid, that can be separated by distillation: (CH3COO)2Ca + H2SO4 -> CaSO4 + 2 CH3COOH. Details in Thorpe, Vol.1, p. 11-24. Just a theoretical.

Baphomet - 25-3-2009 at 04:42

I've tried reacting H2SO4 and Na.Acetate, then distilling it.

The operation was fairly successful but being unable to stir the mixture meant a lot of heat needed to be applied. This resulted in a yellowing of the acetic acid produced, and a smell of SO2 (around 5ppm?)

So perhaps Na2SO4 decomposed during the distillation? My question is: what is the best protocol for doing this?

Also I've noticed that Na.Acetate must go through 3 cycles of roasting and crushing to reach the anhydrous state.. also it should be kept in a sealed container while cooling between cycles. Best results were obtained by grilling first, then using a microwave oven.

Sedit - 25-3-2009 at 06:58

If the sodium acetate was obtained from vinegar then it should be recrystalized to rid it of other organics and possibly traped volatiles. I cant stress this enough because it is the difference between good acid and one that is yellow and will eventually form a scum layer atop of it. You are correct with the time it takes to get the sodium acetate dry. It is a royal pain in the ass but well worth it in the end.

A test with the addition of 35% H2O2 will show you how much other unwanted stuff is in there by forming a clear peracetic acid from the yellow solution and bringing the contamination to the surface where it can be seen clearly as a layer of scum.

After reading thru this threed has anyone as of yet really made it using Bisulfite? I'v used sulfuric many times with good results but I have some Sodium pyrosulfite that I could possibly use to test if no one else has attempted it yet. Im a little concerned with SO2 contamination and release using this though.

crazyboy - 25-3-2009 at 14:18

http://www.apcforum.net/forums/blog/crazyboy25/index.php?sho...

This is how I did it.

no1uno - 4-4-2009 at 05:14

Here is "AN" answer, maybe....

Quote:

In the system ethyl acetate/acetic acid/water, a binary azeotrope exists between water and ethyl acetate (Boiling point 70.4 Deg. C). The separation by distillation of water and acetic acid in the ethyl acetate can be done without too many problems. As far as running costs are concerned. one must take card that the ration of ethyl acetate/water used in the column corresponds to the maximum volatility for acetic acid. Consequently the feeds to the extraction column must be held within closely controlled limits, necessitating a carefully designed control system.

http://www.ddpsinc.com/ProcessProfiles/pp50.html

Separating the ethyl acetate & acetic acid looks likes fun

no1uno - 7-4-2009 at 22:14

Sorry for the double-post (been busy trying to build a website)...

I had that wrong, use the ethyl acetate to extract the acetic acid from white vinegar, then distill off the ethyl acetate/water azeotrope @ 70.4C... What you are left with will be a strong acetic acid solution.

Point 1

I've seen somewhere the suggestion that fractional freezing (?) can be used to purify strong acetic acid solutions, I've no idea as to the validity of these claims.

Point 2

It might be possible to remove the remaining water by azeotropic distillation, using ethanol, or acetone or something similar.

Point 3

In order to dry ethyl acetate, I've seen it suggested elsewhere to use hexane/toluene and NaCl to make a 2-phase solution. Personally I've tried the use of CaCl2 to separate EtOAc/EtOH/H2O, which does form a 2 phase solution, however given the bp of the resultant EtOAc I'd say it was less than completely effective.

PS Anyone got ANY ideas? This is just guesswork till I get my glass again, anyone else want to try it?

starman - 13-4-2009 at 17:38

I don't know about the fractional freezing of stronger solutions,but there are a number of claims of using freezing to concentrate dilute solutions(vinegar) to a concentration of circa 30%.(saw a webpage complete with pictures sometime ago).
This would greatly reduce the ethyl acetate required for extraction and thus increase economy/facility of the process.

16MillionEyes - 14-4-2009 at 17:44

Crystallizing NaCH3COO from the vinegar/NaHCO3 boiled salt can be a serious hassle: it takes days for it to reach a saturated solution of NaCH3COO before it even starts crystallizing; separation is somewhat tedious and, unless done very carefully, does not lead to an acceptable salt; and lastly, the yields are poor.

I think the best way, for anyone with a distilling apparatus, is to distill their white vinegar before attempting anything. Since most people here already suggest fractional distillations and so on for the production of glacial, I don't think this will be much of a hassle. Once you've gotten your relatively pure acetic acid, then work your way to glacial.

In actual terms of the glacial (wasn't there another thread on this, like 6+ pages?), the freezing method works well, only problem is separation. What I mean is that you can definitely note a rise in concentration, but then, as you separate, ice starts to melt and you inevitably end up with a solution of acetic acid. Not a bad thing, but seems like it requires a bit of ingenuity to get it to glacial by this method.

[Edited on 15-4-2009 by __________]

[Edited on 15-4-2009 by __________]

franklyn - 26-4-2010 at 19:37

Quote: Originally posted by starman

I don't know about the fractional freezing of stronger solutions,but there are a number of claims of using freezing to concentrate dilute solutions(vinegar) to a concentration of circa 30%.(saw a webpage complete with pictures sometime ago).
This would greatly reduce the ethyl acetate required for extraction and thus increase economy/facility of the process.

Step 1
http://www.alchemywebsite.com/distillation_of_vinegar.html

Step 2
U.S. Patent 2422504
http://www.sciencemadness.org/talk/viewthread.php?tid=10545#...

Source _
www.soapgoods.com/Activated-Carbon-Carbon-Hydrodarco--p-1007...

.

Sedit - 26-4-2010 at 21:09

Sorry to intrude here on the discussion at hand but I seen this thread revived and wanted to ask a question for everyone here.

What would be the best way to produce AcOH from EtOH in an electrochemical cell? I'v tryed a variety of methods which I couldn't recall off the top of my head without gathering and reviewing my hardcopy notes(most got lost in a computer crash) and what was noted in almost every attempt was a strong smell of Acetaldahyde. This obviously equates to a large lose of product. I also tried oxidation of EtOH with Nitric acid which I honestly feel has much potential but that also yeilds alot of AcO product as well.

I think in terms of economics electrochemical oxidation could be the way to go followed with a salting out of the formed AcOH and DCM extraction. Given that DCM evaporates quickly, cleanly and more importantly its easy to recover even with a makeshift "Bucket" form of distilling apperatus it would allow someone to make large amounts cheep with reusable reagents instead of wasting H2SO4 or a host of other reaents in trying to prepare AcOH. I think it could even beat out Lens Haloform economics if enough for thought was put into its workings.

So any ideas on what to use in a cell to get the oxidation done quickly and easy? What about the AcO formation how to quell its formation enough to give good yeilds? An acidic cell would be best else your back to using H2SO4 to release the AcOH for distillation.

Picric-A - 27-4-2010 at 11:21

I guess acetaldehyde is the intermediate oxidation compound, ie:
ethanol--> acetaldehyde --> acetic acid

Thus you want to leave the acetaldehyde in until complete oxidation, dont try remove it.

bbartlog - 27-4-2010 at 11:37

Quote:

Since most people here already suggest fractional distillations and so on for the production of glacial

Care to point to even one member here who has done fractional distillation of acetic acid and recommends it as a way to produce glacial acid? Because as far as I can tell this is extraordinarily arduous, and no one who has done it seems to think it's the right way to go. I tried this (starting with ~40% acetic acid and using a Hempel column to concentrate the acid) and the separation is simply not efficient enough. Starting with anhydrous reagents and/or using sulfuric acid to trap water in the system seem to be the universally preferred approach.

The WiZard is In - 27-4-2010 at 12:46

Quote: Originally posted by evil_lurker

I'm working on a way to get as close to pure acetic acid without having to order it and pay those outrageous hazmat fees. [snip]

British medical journal
February 23, 1867

Of the chemical preparations in the new edition of the Pharmacopoeia, the acids have probably undergone the most important alterations. The very impracticable process for Glacial Acetic Acid given in the last edition is now omitted ; and we have simply a description of the characters by which the substance is to be recognised. In point of fact, no good process exists by which the acid can be prepared at all economically on a small scale; and, indeed, very little of the acid is made in this country. It is imported chiefly from Germany; and, under these circumstances, a good description was all that was required for pharmacopoeial purposes.

Noted in passing :—

Probable more that you want to know.

William Theodore Brannt
A practical treatise on the manufacture of vinegar: with special ...
1900 543 pages
Google.com/books

bbartlog - 27-4-2010 at 13:22

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 - 27-4-2010 at 17:24

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.

Runningbear - 27-4-2010 at 20:07

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 - 22-10-2010 at 17:20

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.

Sedit - 26-10-2010 at 12:30

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

Sedit - 26-10-2010 at 12:30

Sad to say a large amount of my 1mol scale Glacial acetic acid experiment spilled

entropy51 - 26-10-2010 at 16:45

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 - 8-11-2010 at 14:57

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 - 8-11-2010 at 16:11

? Um.... what?

Random - 8-11-2010 at 16:13

Well, the stronger acid should put out the weaker acid from the salt.

Sedit - 8-11-2010 at 16:22

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.

Hexagon - 8-11-2010 at 16:47

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 - 8-11-2010 at 16:50

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 - 8-11-2010 at 17:15

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.

cnidocyte - 12-2-2011 at 14:58

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.