04-17-04 10:25
No 501244
Hi!
Around here, 99% acetic acid is no longer available OTC, which obviously is a very bad thing. 80% is however available in bulk and at a very low cost. I really dont want to make an acetate, isolate the salt, and then do the whole add sulfuric thing and distill.
Isn't it possible to mix 80% acetic acid and a minimal amount of toluene in a flask, and fit a dean stark trap + condensor? The BP of acetic acid is 117.9oC. Won't the water/toluene azeotrope distill of at 85 oC? In theory this could be caught in the dean trap, and the water subsequently removed.
Then the remaining toluene could be distilled of in a usuall manner.
...or will everything come over as an ugly mishmash and ruin everything?
Regards
Bandil
Nuke the whales!
(Hive Bee)
04-17-04 12:16
No 501256
Toluene forms an azeotrope with acetic acid:
B.Pt. toluene: 110.60°C
B.Pt. azeotrope: 105.40°C
Toluene in azeotrope: 72.00%
But you can distill the 80% acetic acid, the azeotrope formed with water boils at 76,6°C and contains only 3% acetic acid so your losses will be tolerable as you told the 80% acetic is plenty and cheap at yours.
You should get about 730 ml to 750 ml GAA from 1 liter 80% acetic acid this way. Sounds ok to me.
The distillate can be used for salad dressings.
(Synaptic Self-Mutilator)
04-17-04 23:31
No 501366
The only way to get to 100% GAA is to form the acetate and distill from sulfuric acid. Sorry!
Distilling 80% AA, even with a really long column will not get you GAA. Distilling with a solvent that forms an azeotrope will, but it's too hard for a clandestine bee to do it (IMHO!).
Good luck!
(Hive Bee)
04-18-04 01:01
No 501380
The distillation will yield 98% to 99% acetic acid - GAA sufficient pure for almost all purposes is usually made by "freezing out" of the acid gained by distillation.
Vinegar cannot be distilled to yield GAA (or high concentration acetic acid in serious amoounts) - this is obvious from the azeotrope formed with 3% acetic and 97% water.
Another way to GAA from the 80% acetic would be to add ketene or acetic anhydride - more theoretical but it works.
There is NEVER something like "the only way" in chemistry.....
(Synaptic Self-Mutilator)
04-18-04 05:24
No 501420
There is no azeotrope with GAA and water. I have posted the phase diagram in the past. I could post it again if necessary?
I mean the only way in clandestine chemistry--the subject of this board is to form the acetate and distill.
Sure mixing 80% GAA and acetic anhydride will work (after the AA hydrolyzes)... but if the poster had that, they'd also have GAA easily available. Ketene, yeah, it's OTC from acetone pyrolysis--but have you done this? It's actually fairly freaky.
Freezing out pure acetic acid won't work either. Have you tried this? I could not get it to work with 80% acetic acid. Go ahead. Try it and post back your results--but don't respond with knowledge gained thru academic knowedge on this subject!
My posts come from experience--not theoretical knowledge.
(Hive Bee)
04-18-04 11:38
No 501454
"There is no azeotrope with GAA and water"
- after several databases on azeotropes there is.
"Freezing out pure acetic acid won't work either. Have you tried this? I could not get it to work with 80% acetic acid."
- of course freezing out does not work well with 80% acetic acid. As I told before, you have to distill it before and freezing out is the last step to GAA. Freezing out is a little tricky as it needs patience for not to cool down to fast and to deep and to include water in the crystal lattice of the frozen acetic acid. Vacuum filtration is a "must do".
I used freezing out quite often in the past.
Reposting or linking to this diagram you spoke about would be highly appreciated.
regards
rAg
EDIT: After some deeper investigation onto this I came to the conclusion that "freezing out" is a useful way to concentrate acetic acid with an concentration over 95%.
But it actually seems that although acetic acid forms an azeotrope with water it is not feasible to distill this azeotrope out for what reasons ever, so simple distillation of the named 80% acetic is no way. Azeotropic distillation might be - benzene, chloroform, DCM should work, but after consulting some books of practical wisdom (written before 1900
) I came to the conclusion that Chromic is right on the point when he says that the best way for concentrating the 80% acetic acid to GAA is by forming an acetate followed by distillation with conc. H2SO4.
(Newbee)
04-18-04 21:31
No 501505
Acknowledging that it's at least a touch offtopic, could you help out the less daring among us by elaborating on "freaky"? I'd been contemplating giving this a (very, very careful) try in the next few months, and any lessons learned would be helpful.
(The Archetypical "Good Guy")
04-19-04 11:08
No 501596
Im quite sure that 97% acetic acid would be fine enough for the knoevangel condensations. As far as i can figure out, a simple distillation of 80% acetic acid would give 97% acetic acid? Is there any reason the remaining water cant be removed by using sodium sulfate or any other dirt cheap drying agent?
Its not a problem getting the real solvents, i just try to avoid the chem. companies whenever possible!
Regards
Bandil
Nuke the whales!
(Hive Bee)
04-19-04 16:04
No 501611
No. I was wrong on the distillation - concentrating 80% acetic acid to 95%+ acetic acid wont work by simple distillation - using a water carrier like benzene would be possible but tedious and not practical as Chromic told.
Freezing out:
There is some confusion on this because there are two ways "freezing out" is used.
- First in the concentration of vinegar, whereby WATER is frozen out - this gives acetic acid with an concentration up to 30% - not more.
- Second, all acetic acid with an concentration over 95% can be frozen out whereby here the ACID is frozen and the water stays liquid and can be sucked off from a Buchner funnel with vacuum.
But Chromic was right: From 80% acetic acid to GAA the way is by the acetate/H2SO4 distillation.
Sorry.
RaG
(Heavyweight Chempion(eer))
04-20-04 00:24
No 501663
I have no references for this so I might be talking out of my ass here, but shouldn't it be possible to bind most of the 20% water in 80% AA with sulfuric acid since it tends to hold on to its water rather strongly. Calculate how many mols of water say 500 ml 80% AA contains, add an equimolar amount of conc. sulfuric acid and distill off the AA. The sulfuric acid should be reusable by distillation if one so desires. Perhaps the distillation of the AA is best performed under reduced pressure?
(Stranger)
04-20-04 10:25
No 501742
Now there's an idea I like. I posted a similar (identical) idea a couple of weeks ago, but it got UTFSE-rated.
Question is if the sulphuric acid will do any damage to the AA... I don't know, only experiments will tell I suppose.
Unfortunately I've experienced that dilute sulphuric acid will not emit the water it contains upon heating/distillation, so recovering it is probably not an option (haven't tried vacuum distillation though).
The fact that I couldn't dehydrate sulphuric acid even on excessive heating only proves Bariums point though, let's just hope it won't do the same thing to AA.
(Heavyweight Chempion(eer))
04-20-04 11:25
No 501758
AA should not be attacked under these conditions. You sure can remove the water from dilute sulfuric acid, but it requires quite high temps since it really holds on to water.
(Hive Bee)
04-20-04 11:27
No 501759
Question is if the sulphuric acid will do any damage to the AA... I don't know, only experiments will tell I suppose.
Sulphuric acid does not "harm" acetic acid, at most it might dehydrate it if sulphuric acid is in excess with water. In such case only some acetic anhydride might form.
Unfortunately I've experienced that dilute sulphuric acid will not emit the water it contains upon heating/distillation, so recovering it is probably not an option (haven't tried vacuum distillation though).
Off course it works. I used to concentrate 35% sulphuric acid when I needed it for the HCl gas generation. I just boiled the acid under low pressure of a water jet (don't forget the water trap!) and it concentrates it just perfectly. I never measured its density (concentration) but it was just perfect for HCl gas generation from 30% HCl. From the volume reduction I would guess it was above 85%. And the rests of this HCl dehydration can bee regenerated again if one has enough patience.
“The real drug-problem is that we need more and better drugs.” – J. Ott
(Stranger)
04-20-04 11:36
No 501761
Well, then I screwed up when trying to distill it and I'll give it another go.
This however seems to be the most promising way of dehydrating the AA and I will definately try it out within a couple of weeks! I'll post whatever results I get from it.
(Stranger)
04-20-04 12:04
No 501767
Nicodem,
I never applied any vacuum, as I mentioned. I also started from 35-37% (d = 1,3 or so) sulphuric acid, and ended up with d ~ 1,6 (~70%), which I don't think of as concentrated sulfuric acid. So yes, in my case, some of the water did leave the solution, but the last ekv. of water is pretty damn protonated and stuck in the acid. And this seems reasonable since 85% (the approximate concentration of your acid) H2SO4 contains pretty much 1:1 H2SO4:H2O.
(Hive Bee)
04-20-04 13:14
No 501769
NOVICE, if you should try this "dehydrating acetic acid by conc. H2SO4" please wear a gasmask or use a fumehood or at least a strong fan blowing the fumes away from you out of a window. CO is deadly you must know.
(Stranger)
04-20-04 13:31
No 501772
ragnaroekk,
Thank you, I appreciate your concern. I always use my 1 kW fan driven fume outlet whenever I'm going at it in the lab ;)
You mention CO is deadly, and I wonder if you insinuate that CO is formed during distillation? Both Nicodem and Barium mention that the AA will not decompose or whatever, do you have some other information on this matter that we have not taken into account?
(Hive Bee)
04-20-04 14:46
No 501782
1kW fan, now thats what i call a FAN!
And CO generation... where is that coming from might i ask? if not decomp the AA wheres it coming from?? Rag??
(Chief Bee)
04-20-04 17:52
No 501818
Carbon monoxide is formed by dehydration of formic acid with sulfuric acid, not acetic acid.
The Hive - Clandestine Chemists Without Borders
(Moderator)
04-21-04 02:01
No 501895
As far as the original topic of this thread, see Patent US2275802 and Patent US2028800 for the proper approach
Another bee friendly method from the past is CA 41 4445g (1947) using activated charcoal 
Chemistry is our Covalent Bond
(Synaptic Self-Mutilator)
04-21-04 06:19
No 501964
Activated charcoal can not be used to form glacial acetic acid--just to remove impurities in the GAA (similar to how you remove fusel oils from EtOH with activated charcoal and 50% EtOH). Actually, acetic acid is preferentially is adsorbed onto activated charcoal (i.e. preferential to the water). :)
From what I understand, you absolutely need to do azeotropic distillation with an column containing a large number of theoretical plates to concentrate dilute acid... here is the phase diagram data for water/AcOH from Perry's (to the right is w/w %'s I calculated from the mol frac data):
mol frac w/w
Temp liquid vapour liquid vapour
118.3 0 0 100 100
110.6 0.1881 0.3063 93.5 88.3
107.8 0.3084 0.4467 88.2 80.5
105.2 0.4498 0.5973 80.3 69.2
104.3 0.5195 0.658 75.5 63.4
103.5 0.5824 0.7112 70.5 57.5
102.8 0.675 0.7797 61.6 48.5
102.1 0.7261 0.8239 55.7 41.6
101.5 0.7951 0.8671 46.2 33.8
100.8 0.8556 0.9042 36.0 26.1
100.8 0.8787 0.9186 31.5 22.8
100.5 0.9134 0.9409 24.0 17.3
100.2 0.9578 0.9708 12.8 9.1
100 1 1 0 0
If you take the time, and plot it, you'll quickly see why you can't just do a simple distillation to sufficiently purify the acid.
If you use a very long column with a good packing and with a high reflux ratio (ie nixon-stone type reflux head), then... yeah, you could go from 80% to nearly 100% without doing an azeotropic distillation. Do you guys have this sort of equipment? likely not... if you did, you wouldn't be asking this question. :)
A simple nixon-stone type arrangement can be made using a 24/40 RB flask attached to a very long 24/40 tube (male/female ends) that works as your column (filled with inert packing material), then a dean stark adapter (with stopcock), then a claisen adapter to monitor the temperature, then a reflux condenser ontop of that...) Set it to a healthy boil, so that the reflux rate thru the column is fairly regular, then only open the stop cock a bit to collect a rate of distillate considerably less than the rate of reflux.
Let us know how it goes... I'd love to find a better way. I've got a ton of this diluted acetic acid myself.
(acetaminophanatic)
04-29-04 04:47
No 503664
To nings coarse ears, the idea of sulfuric acid "damaging" acetic acid is rediculous. What do you think is formed when you add sulfuric acid to sodium acetate? I don't think the two ways are going to bee different in any way, except one makes a lot more salt than the other
It's a good idea. Very useful.
And what if someone were to investigate the production of acetic anhydride by using concentrated sulfuric acid on acetic acid?
What would happen if one were to add SO3 to acetic acid?
I've been chased by both cops and robbers. So what does that make me?
(Hive Bee)
04-29-04 08:17
No 503687
methinks, if we are talking maximum concentration sulphuric acid, then this could dry the water off and prevent the azeotropism similar to how the Na-acetate decomposition likewise allows you to remove the water before distilling the acetic acid.
theoretical of course
thou knowest
(Wonderful Personality)
04-29-04 09:57
No 503706
And what if someone were to investigate the production of acetic anhydride by using concentrated sulfuric acid on acetic acid?
What would happen if one were to add SO3 to acetic acid?
In the first case one would find out that conc. H2SO4 doesnt produce acetic anhydride from GAA.
In the second case one would find out that the good reverend Drone was right: SO3 actually produces AA from GAA.
But: Will SO3 produce AA from sodium actetate?
I am still not a bit convinced that the addition of conc. H2SO4 is a practical way to GAA from 80% acetic acid, but I may be wrong. The procedures for GAA from sodium acetate call for anhydrous conditions as I remember. I guess that for drying 80% acetic acid so much conc. H2SO4 will be needed that the procedure gets highly ineffective.
(Hive Bee)
04-29-04 10:56
No 503716
a few books (not by Professor Buzz or Uncle Fester) say that if one distills conc. acetic and sulfuric acids (at least 70%H2SO4 is ok though) then one gets some black crap, C, CO2, and SO2. everything is fine until you distill, they say. how little water must there be? dunno, never tried it. yes, i know the decomposition of HCOOH is usually mentioned, without comment on acetic. no mention of dehydrating abilities of the 70% H2SO4, just a patented method for destroying formic contaminant without hurting the acetic. i always see some blackening in pockets when i drop 93% H2SO4 onto dry Ca acetate, but not a whole lot. this is not the same as distilling the conc. acids anyways. there must be a reason why taking off that last few percent of H2O with sulfuric is not an established procedure AFAIK. i'll do an experiment tomorrow, though with my crap-grade acids this may only be of interest to OTC material bees, if anyone.
there are several patents that use drying agents. copper sulfate and vacuum is popular for many acids. metaphosphoric acid. solvent extraction with benzene, an ether, chloroform, ethylene dichloride...though these are probably not helpful in this case and off-topic. there are a number of alternatives, but AFAIK involve acetate salts, not what was wanted here. just had to add to the sulfuric posts, though i realize conc. sulfuric probably wouldn't hurt in this case, since the acetic isn't so concentrated.
i've heard of (old, not on espacenet) patents that describe addition of SO3 to GAA, addition of this to Na acetate, to give acetic anhydride in moderate yield at low temps, btw. perhaps useless rumours.
http://www.maps.org
(Newbee)
04-29-04 11:00
No 503719
Somehow I think the sulphuric acid will hold on to all the water it can find, even at 120 C... If one adds a slight molar excess to the 80% AA, it should yield GAA upon distillation. Wouldn't it seem unreasonable otherwise?
If you consider delta H for the reaction H2SO4 + H2O --> H3O+ + HSO4-... I get the feeling that there are no side reactions (such as AA + H2O) that are even near as favoured as the one between sulphuric acid and water.
(acetaminophanatic)
04-29-04 16:56
No 503752
Organikum, I was thinking he should first distill the acetic acid, or freeze it, or whatever to get to 95-98% purity, then distill from sulfuric acid to remove that last bit of water.
I doubt pure SO3 could make acetic anhydride from NaOAc. You need some hydrogens there, I think. IIRC, SO3 is not acidic at all when pure. But hey, maybe if there was just a little bit of water, (oleum?) it could start a chain reaction.
H2SO4 + 2 NaOAc --> 2 HOAc + Na2SO4
2 HOAc + SO3 --> Ac2O + H2SO4
and repeat.
I don't see any reason why not. Only problem is, you'd have to titrate your SO3 fairly accurately, otherwise distillation could get interesting...
Say, maybe you wouldn't need to distill. probably Na2SO4 isn't soluble in Ac2O. perhaps you could just pour it off.
I've been chased by both cops and robbers. So what does that make me?
(Hive Bee)
04-29-04 20:20
No 503788
Ning, the reaction of SO3 and NaAcO is formally possible:
SO3 + 2 MeCOONa => Na2SO4 + (MeCO)2O
...though I have no idea if it is practically possible.
You see, CO2 is also not acidic but it will nevertheless react with solid Ca(OH)2, for example, forming CaCO3 and water. Even more, it will also react with CaO forming only CaCO3. These are not acid-base reactions anymore.
“The real drug-problem is that we need more and better drugs.” – J. Ott
(Hive Bee)
04-30-04 00:36
No 503819
Generally, sulphuric acid pushes all other acid ions out of the conjugations, and in this situation, the main two products of the reaction would be sodium sulphate and free acetic acid.
Sodium sulphate is a very strongly hygroscopic salt and the acetic acid hasn't got a snowflake's chance in hell of holding the water, 80-90% sulphuric acid hardly has any water in the first place, and the sodium sulphate will form the decahydrate... Every mole of sulphuric acid will pull this ratio of things out of the system - here it is with the total amount of water that could be present before the acetic acid could actually grab onto it:
(H2O)10 + (NaCH3COOH)2 + H2SO4 --> Na2SO4 + (H2O)10 + (CH3COOH)2
here's the formula with the weight of one mole of each chemical corresponding with that formula:
180 + 164 + 98 --> 142 + 180 + 120
This means, by weight, sulphuric acid dissolved with a weight ratio of 98:180 sulphuric acid to water (what's that - 50%ish) will be retained by the formed sodium sulphate. So any more concentrated sulphuric acid than that will most definitely completely dehydrate the sodium acetate, sans decomposition temperature requirement of the dry acetate distill.
at least, in theory.
thou knowest
(acetaminophanatic)
04-30-04 04:28
No 503866
I think it would probably be very much like reaction of CO2 with Ca(OH)2....CO2 could bee called "carbonic anhydride", and much like SO3, it's not acidic at all....until it encounters water. Then there is formed the famous HOCOOH, which can immediately react acid-base wise with Ca(OH)2 to form the carbonate.
I wonder, will dry CO2 react with dry CaO? Even when both are perfectly anhydrous?
Way I think of it is, CaO is like a basic anhydride. CO2 is an acid anhydride. Whether they actually become the acid or base transiently when they react is not so important as realizing that the reaction will run down the energy hill.
CaO + H2O --> Ca(OH)2 = Energetically favorable
CO2 + H2O --> HOCOOH = hmmm. Not so favorable, not unfavorable. Equilibrium.
Ca(OH)2 + HOCOOH --> CaCO3 + 2 H2O = Energetically favorable
Imagine there was only a very, very small amount of water. It would still enable the reaction to take place, with the overall equation CaO + CO2 --> CaCO3. And if it still works under perfectly anhydrous conditions, so what? You could still figure out the reaction was energetically favorable from acid-base equations.
So, while I agree acid/base chemistry isn't the end, it sure is useful.
So whether the reaction SO3 + 2 NaOAc --> Na2SO4 + Ac2O actually involved transient hydration or not, I bet it will still work. SO3 is a very, very angsty molecule.
Organikum recently forwarded me a very interesting idea that avoids the need for getting up close and personal with Mr. T (Trioxide, that is):
http://www.sciencemadness.org/talk/viewt
near the bottom, there is mentioned a patent that says sodium pyrosulfate can dehydrate and free from salt sodium acetate.
2 NaHSO4 --heat--> Na2S2O7 + H2O
Na2S2O7 + 2 NaOAc -----> Ac2O + 2 Na2SO4
I guess NaHSO4 can bee made by carefully neutralizing sulfuric acid only half way.
Read the original post, that sounds too tasty. Perhaps even a one-pot procedure?
I've been chased by both cops and robbers. So what does that make me?
(Wonderful Personality)
04-30-04 11:25
No 503957
elfspice, how do you come to the funny belief that sodium sulfate is more hygroscopic than acetic acid or sulfuric acid?
Because we could easily dry acetic acid by NaSO4 if this is true ya know?
Life is so easy when you just have to talk about, and its so hard when you actually have to do it.
(Hive Bee)
04-30-04 11:51
No 503961
I think that would be quite likely actually
H2SO4- + (4HCOO-)--> (CO2)4 + H2S + (H2O)4
the formic acid would reduce the sulphuric acid's oxygens until it formed H2S, and there would be a whole series of intermediate sulphur acids in between.
Still seems to me that decomposing sodium acetate still comes out on top.
The only caveat to that method is occluded water, water of crystallisation. It would cross with the acetic acid.
In reality it is Na+.CH3COO-.H2O, and thus the stuff you get at in the receiver is CHCOO-.H2O
that's 60:18, or in other words, 70%
So, i think the best option would be to put a drying tube in between (pardon me for repeating already known information if this is already known), containing a dehydrated salt like CaCl or sodium sulphate or whatever.
Or can the water of crystallisation be driven out of the sodium acetate without releasing the water, say perhaps simply by holding the temperature at 100 degrees until no more moisture comes out of the salt. This could be monitored by distilling it, and when the constant boiling temperature fails to drive any more water out of the salt, the receiver is switched and one collects 98% or so perfect dry acetic acid. To ensure that this does occur, one of those cow teat type receiving adapters, and in the flask put an excess of drying agent which has the purpose of retaining all the moisture that will drip out of the condenser, and helping the internal atmosphere remain dry. A drying tube will also be neccessitated as the distillation will need venting but it cannot let water in. Once water stops distilling, the receiving flask for the dehydrated acetic acid is put in the position for receiving and the temperature raised to the decomposition temperatuer of the sodium acetate.
thou knowest
(Wonderful Personality)
04-30-04 14:15
No 503979
I really dont know what you are talking about elfspice, but I assume you dont know it either so it doesnt really matter.
I admit frankly that it sounds impressing though.
Formic acid and conc.H2SO4 produces carbonmonoxide as Rhodium told already.
(Hive Bee)
05-03-04 01:18
No 504446
molecular sieve could be used to bind the water? CaO is often used to absorb the water i EtOH to obtain 100% but i dont think this could be used in this case, because it form the hydroxyl with water. anion exchange resin could be used to concentrate the gaa, but you would need a resin that dont deformate under high ionic concentration...
(acetaminophanatic)
05-03-04 05:08
No 504497
Make sure you don't try using anything that will react. Like calcium oxide. Sieves? Dunno.
How about this? Post 463967 (hermanroempp: "Re: sulfur????", Novel Discourse)
NaHSO4 + NaOAc --> HOAc (glacial)
Alternately, ning suspects that anhydrous sulfate salts (Na2SO4, MgSO4, etc) may be able to dehydrate the acid. Sodium sulfate in particular was supposed to bee very strong if fully dehydrated. (is this so?)
I've been chased by both cops and robbers. So what does that make me?
(Heavyweight Chempion(eer))
05-03-04 11:27
No 504550
Sodium sulfate is almost useless as a deccsicant at temps above 36-37 deg C.
Severe Aztecoholic and President of Sooty's fanclub - Sooty for President!!
(Hive Bee)
05-03-04 15:44
No 504571
Ning said :
Organikum recently forwarded me a very interesting idea that avoids the need for getting up close and personal with Mr. T (Trioxide, that is):
http://www.sciencemadness.org/talk/viewthread.ph p?tid=9& page=2
near the bottom, there is mentioned a patent that says sodium pyrosulfate can dehydrate and free from salt sodium acetate.
2 NaHSO4 --heat--> Na2S2O7 + H2O
Na2S2O7 + 2 NaOAc -----> Ac2O + 2 Na2SO4
I guess NaHSO4 can bee made by carefully neutralizing sulfuric acid only half way.
Read the original post, that sounds too tasty. Perhaps even a one-pot procedure?
This was actually raised before __> Post 462958 (Rhodium: "Na-Acetate + Na-Pyrosulfate -> Acetic Anhydride", Novel Discourse)
Mountain Boy
(Hive Bee)
05-07-04 11:16
No 505559
some of the patents i was thinking of were on espacenet after all. the best one wasn't, was probably too good to be true. maybe these are as well. patents can be a little vague.
acetic anhydride from acetic acid and sulfur trioxide: Patent GB283781
acetic anhydride from acetate, sulfur trioxide with or without another salt, and GAA: Patent GB191517920
acetic anhydride from GAA/acetic anhydride, oleum, and NaOAc: Patent GB191312042
and as for azeotropic distillation, the chloroform/H2O azeotrope boils at 56°. it contains 2.8% H2O, so one would need a bit of it. it contains no acetic acid and chloroform does not form any sort of azeotrope with acetic acid.
elfspice: i believe the reaction of H2SO4 gives CO and water, and that is all. the patented reaction i mentioned earlier about formic-contaminated acetic: Patent US1210792
it also mentions the decomposition of acetic acid by hot H2SO4.
http://www.mindstates.org