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Author: Subject: Acetic acid/ sodium hydroxide
guaguanco
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[*] posted on 8-1-2004 at 15:14


Quote:
Originally posted by unionised
My (1991) edition still says it doesn't.

Old CRC good; new CRC better (because they have removed some of the mistakes).

It doesn't matter how many times you check it if it's wrong.
Has anyone out there got a still, a thermometer and some vinegar? That way we can get can experimental verification one way or the other.

Interesting. I have always heard it forms an azeotrope! In fact, I thought that was how 'distilled white vinegar' is formed. Odd that it took so long to overturn; I'd still like to read something that definitively settles the issue...
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[*] posted on 14-1-2004 at 09:33
acetic acid production


Acetic acid, CH3COOH, is a colourless, waterlike liquid that has a piercingly sharp, vinegary odour and a burning taste, vinegar is its dilute aqueous sol'n and was used in the earliest languages of antiquity. Theophrastus (372-287 BC) presented a definitive study of vinegar's use in the production of white lead and verdigris manufacture. His work was closely followed by the encyclopediast Pliny(23-79 AD).

The term "Acetic Acid" was first coined by Libavious (1540-1600 BC). Many attempts to prepare "icy" acetic acid by repeated distillation were made, but the subsequent failures prompted Lavoisier to make a distinction between "acetous and acetic acid". Shortly after Lavoisier's death, the connection was proven by Adet and others. Final proof was obtained when Kolbe first prepared acetic acid from its elements in 1847.

Acetic acid (glacial) is commonly prepared from the distillation of wood in the Soviet Union, however only the credits from the distillation byproducts makes this process economic, one can imagine that the byproducts must be so great as to make this an entirely impractical process for the amateur chemist.

The historical preperation of acetic acid by dry distillation of metal acetate salts seems most practical. Many acetate salts are commonly available OTC. The most common of which is sodium acetate. If one wanted to prepare acetic acid from common household vinegar, the logical step would be to prepare an acetate salt of a commonly available powdered metal (like copper), react with the vinegar to form the corresponding acetate, evaporate the excess water, dry the salt, and then dry distill (decompose) to form the concetrated acid. The powdered metal could probably be reused indefinitely.

Much thanks to the Kirk-Othmer encyclopedia of chemical technology, third edition.
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[*] posted on 14-1-2004 at 14:57


The heating of the salt can also form Acetone. Calcium Acetate specifically comes to mind. I don't know exactly what happens with +1 metal ions or transition elements. The Hydroxide and Ketene might be possible. Well, the formula works anyway. I've always been under the impression that to go from metal salt to coresponding acid you needed to add another strong acid and distill/precipitate/filter whatever the case may be.
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shocked.gif posted on 15-1-2004 at 20:43


copper acetate monohydrate melts @ 115°C and decomposes @ 240°C. I couldn't find at which T it loses its water but it certainly much lower than its dec T. maybe by destructive distilling you first collect water and then acetic anhydride which react ...
so MAYBE:
Cu(OOCCH<sub>3</sub>;)<sub>2</sub>.H<sub>2</sub>O <s>&nbsp;&nbsp;&nbsp;></s> Cu(OOCCH<sub>3</sub>;)<sub>2</sub> + H<sub>2</sub>O
Cu(OOCCH<sub>3</sub>;)<sub>2</sub> <s>&nbsp;&nbsp;&nbsp;></s> CuO + (CH<sub>3</sub>CO)<sub>2</sub>O(:o)
(CH<sub>3</sub>CO)<sub>2</sub>O + H<sub>2</sub>O <s>&nbsp;&nbsp;&nbsp;></s> 2CH<sub>3</sub>COOH
wow if this really makes acetic anhydride it'll be one of the best methods (requires low temps, is simple and recyclable)




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[*] posted on 16-1-2004 at 02:56


Maybe it will form acetone and copper carbonate (like the calcium salt) and then the carbonate will decompose. I hope this happens at lower temperatures than with calcium acetate, would be a very nice acetone production!
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[*] posted on 19-6-2004 at 16:56
Acetic Acid


Can vinegar (5% acetic acid) be distilled to 100% glacial acetic acid, or is there an acetic acid-water azeotrope? I haven't found anything on such an azeotrope, so I'd appreciate any information anyone might have.
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[*] posted on 19-6-2004 at 17:08


There may or may not be an azeotrope, it was the subject of discussion in this thread.

[Edited on 6/20/2004 by BromicAcid]




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[*] posted on 19-6-2004 at 18:59


Chemists who have been dead for almost a hundred years say that acetic acid of any strength can give some glacial acid on distillation. You'll need a lot of it, because some of it will distill before you get to that point. The old references all point to Henry Enfield Roscoe and a J. Chem. Soc. article of his. Note that I said glacial and not 100%.

Given the energy needed, and the ease of other methods, this is not done, and I guess that it never was, industrially. Thus little info.

Finally took a minute (literally) to go to rsc.org to find the vol/page of the mentioned article: Roscoe, JCS, 15, 270-276 (1862)

[Edited on 21-6-2004 by S.C. Wack]
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[*] posted on 19-6-2004 at 19:29


I'm going to try and concentrate acetic acid at very low temperatures and see if that works. Kind of like how some people say they concentrate H2O2. I just haven't gotten around to it yet.



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[*] posted on 19-6-2004 at 22:56


Acetic acid boils pretty close to water, no? Like, a 15 degree difference...I don't know if that will make a difference, but perhaps your boiling water vapour would be tainted with acetic acid...

I always thought that it was better to form sodium acetate and then collect this salt and react it with H2SO4 while heating and collecting the acetic acid that boils off..

There must be better ways.

Even hydrolysing aspirin gives off acetic acid, and maybe that would be cheaper and more efficient for you...

Anyways, haven't put a lot of effort into making this chemical so I suggest you check out that thread..




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[*] posted on 19-6-2004 at 23:27


Glacial acetic acid (which is of very high conc, ie 99.8% - nothing is ever 100% :P) has a boiling point of approx 118 deg celcius. The solution of the ethanoic acid in water as found in vinegar assumes the physical properties of water, such that the boiling point falls to 100 deg celcius. I think the best method if one wants to produce conc. ethanoic acid is either oxidation of conc. ethanol with KMnO4/H+ or else the method mentioned by thunderfvck which I think is best:

Quote:

I always thought that it was better to form sodium acetate and then collect this salt and react it with H2SO4 while heating and collecting the acetic acid that boils off..




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[*] posted on 24-6-2004 at 11:18


Will only H2SO4 work properly here, or will other acids work too?

2NaC2H3O2 + H2SO4 --> 2HC2H3O2 + Na2SO4, right?

So, NaC2H3O2 + HCl --> HC2H3O2 + NaCl?


On a sidenote:
For the production of sodium acetate, an excess of vinegar is better than an excess of baking soda, right? The vinegar remaining after all baking soda is gone should just boil off...
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[*] posted on 24-6-2004 at 11:49


Please search before posting & continue the discussion in the existing threads.

I'm merging them.




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[*] posted on 25-6-2004 at 01:23


acetic acid and sodium hydroxide could be produced via electrolysis if you had all the time in the world and quick electricity at your disposal..

Just dump the salt into 2 bowl, dissolve them, get a salt brodge to connect the two bowls. Then, insert graphite rod to each of the bowl. You might get acid at the anode, and the hydroxide in question at the cathode. But like i said, you need lots of electricity to use, and you might have to electrolyse a few days..




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[*] posted on 1-7-2004 at 12:01


I had one of those moments today, maybe it's genious or perhaps it's just stupid:

Anhydrous citric acid melt at 153°C and decomposes below its boiling point at 175°C. Acetic acid boils at 118°C.

Citric acids pKa's:

pKa1
3.15
pKa2
4.77
pKa3
5.19

Acetic acid's pKa: 4.78

What about mixing anhydous NaOOCCH3 and citric acid and heating to ~160°C and then condense the CH3COOH?

Is this method possible? If so: is citric acid bought in food stores anhydous (I'm guessing it's the monohydrate).

[Edited on 1-7-2004 by TheBear]
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[*] posted on 5-7-2004 at 10:27


Had another thought:

What about using ammonium acetate which has a melting point of 114C? Heating NH4OOCCH3 together with stochiometric amount of citric acid? If noone can see any problems with this procedure I will try to make some glacial acetic acid with it soon.
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[*] posted on 5-7-2004 at 13:13


You might start to produce acetamide.
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[*] posted on 11-7-2004 at 19:26


If you use acetic acid you will definatly produce acetamide. What you are describing is almost a direct excerpt from Vogel. Check out page 401. The only thing different is the reaction time. You might not allow for the full conversion with your time.
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[*] posted on 14-7-2004 at 12:15


Ahh I see.. Well when I want acetamid I will try that.. but for now: glacial acetic acid is the goal!

So I have to get rid of the ammonium ion, what about Cu(OOCCH3)2 which has a melting point of 115C, which is bellow the melting point of citric acid. Or will the CuAc2 start evolving CO(CH3)2? Can't find any information on this point, it was however mentioned somewhere on this board.

(Hope citric acid works for this reaction and won't decompose)

Offtopic: This experiment has been delayed due to construction of a new fume hood.

[Edited on 14-7-2004 by TheBear]
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[*] posted on 17-7-2004 at 09:58


from; Textbook of organic chemistry, Noller, 1958
...4-10% of acetic acid which may be recovered by neutralizing with lime and distilling to dryness. The gray acetate of lime so obtained may be converted to glacial acetic acid by concentrated sulfuric acid. In recent years acetic acid has been removed from dilute aqueous solutions by extraction from the vapor state with tar oil(Suida process), and by azeotropic distillationusing ethylene chloride, propyl acetate, or butyl acetate to form a constant boiling mixture with the water(Clarke-Othmer process). It may be recovered as ethyl acetate by esterfying with ethyl alcohol."

[Edited on 17-7-2004 by rogue chemist]
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[*] posted on 17-7-2004 at 18:58
Ca(CH2COOH)2 route to glacial acetic acid


This looks like a really straigtforward and cheap way to make glacial acid. I can hardly wait to try it. As Mendeleev has stated "sulfuric acid is just so damn useful." It should be the right of every citizen to bear H2SO4.:D



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[*] posted on 17-7-2004 at 22:57


No, Magpie, It should be the patriotic Duty of every citizen to bear H2SO4.
:cool::D;):P
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[*] posted on 18-7-2004 at 03:34


Magpie, I'm pleased to see you like the method based on Ca acetate. Did anyone like it back in January?
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[*] posted on 18-7-2004 at 09:26
credit where credit is due


unionized,

:P You don't let me get away with anything!

Yes, I do remember that you suggested the acetate method some time ago. I liked it then too. I like your freezing method also.
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[*] posted on 18-7-2004 at 12:34
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I tried freezing 5%ethanoic acid- (sounds much better than vinegar) The whole thing froze into a solid mass. Hmm.

I made some sodium acetate (guess how;))and boiled it down to dryness in an iron pot. I will try adding H2SO4 and distilling. My concern is that sodium acetate is efflorescent. Anyone know how much sodium acetate is lost when boiling it down? Anyways, I love the smell of the process, a cross between freshly baked bread and vinegar. :)
Calcium acetate doesn't have the same problem, I might try that.






[Edited on 18-7-2004 by Cyrus]




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