Author Topic: Glacial acetic acid from aq solutions (Read 779 times)

Sedit · « **Reply #20 on:** September 25, 2009, 12:26:45 AM »

Java provided the papers sadly that is not true like I hoped Poison.

According to the papers the salting out effect increases in the direction of,

Potassium chloride < sodium chloride < potassium ethanoate < calcium chloride < sodium carbonate < potassium carbonate.

It would appear from the above that Sodium carbonate and Potassium carbonate are just about equals but Table 1 shows us that,

Salt D_al/D_o

KCl 3.34
NaCl 3.86
AcOK 4.5
CaCl2 4.73
Na2CO3 5.55
K2CO3 19.23

Where D_al is the ratio of IpOH concentrations in the organic phase to that in the aq phase. D_o is the ratio before salt is added.
[/list]

Sedit · « **Reply #21 on:** September 25, 2009, 08:05:24 PM »

Second extraction is looking great and I may have just found my missing yeilds for sure. The IpOH is just about gone now obvious from the beading forming in the condenser and the strong smell of AcOH in the distillate and from the looks of it I may have a large relativly amount of crude AcOH remaining in the flask. I shut it down because I have to leave but later I will be able to report yeilds.

This would mean that it could all be done in one step by salting out with two seperate portions of IpOH and then combining them before distilling the mixture.

I am also starting to think that forming the ester is a good thing since as I understand it decomposes to IpOH and AcOH with heat. Given its low solubility in water forming the ester and seperating will be a snap and then a quick reflux to decompose before distilling could yeild very dry and very pure Glacial acetic acid.

OK gotta run....

Sedit · « **Reply #22 on:** September 26, 2009, 05:28:30 AM »

Well it looks as though I have only lost a few ml in the extraction process. I have no direct numbers at the moment because its very damp outside and I sealed the new AcOH distillate as quick as I could to prevent it from sucking up moisture in the air. Tommorow when the suns out and its not so humid outside I will measure how much I have but from the looks of it I am only a few ml shy of the what the first distillate measured. This means out of 80ml I recovered about 70 give or take. This is more then expected considering some of the "80"ml could have been IpOH.

Happy as a clam since I only needed like 10ml from the start I think I will turn the whole shee-bang into AcOH-HBr solution for future use.

Can someone suggest something better then MgSO4 for drying? I need it dry as can be for hydrobromination reaction of an alkene. MgSO4 has a hard time getting it to where I want it to be. Normaly I would use lithium to dry something completely but in this case I can not use it here so what should I do?

Perhaps polyphosphorics acids could dehydrate and provide me with the non oxidising acid I need all at the same time?

All in all I think it is about time to release this information in a published form. I wish I had my cable for the camera but I can not find it

. I will work something out.

Stay tuned because Im getting more DCM tonight and am going to try to make ALOT of AcOH tommorow from NaOAc + HCl then salt out and extract with DCM.... Wish me luck folks.

Douchermann · « **Reply #23 on:** September 26, 2009, 06:07:25 AM »

I'm a big fan of molecular sieves, even a 4A can remove H2O leaving the AcOH. Just be sure to remove the seives before adding HBr. Molecular sieves are suitable replacements for sodium in applications such as ether drying for grignards IIRC, just to give you an example of their power.

Sedit · « **Reply #24 on:** October 22, 2009, 02:39:26 AM »

Ok after a little bit of test tube testing I have been able to oxidise EtOH to AcOH in what appears to be higher yeilds then I thought. When it hits temperature fine bubbles like soda fizzing start and even on such a small scale run for about 5-10 minutes before the reaction dies down. Its not extremely strong reaction but pretty steady.

I decided to pay no mind to the Acetaldahyde being formed since its smells strong at lower levels and I worked up the results by adding sodium bicarbonate. After it was neutral I evaporated the Solution to gather my NaOAc and acidified with H2SO4 smelling strongly of acetic acid and a hint of formic acid or something more then likely from MeOH as the denaturant.

I now want to do a larger test but the issue presents itself of workup now. I want to seperate EtOH, H2O, AcOH and Dissolved Acetaldahyde. I can not distill the EtOH since that will carry AcOH along with it. Salting out as a first step could also be a problem since the salt will not be very soluble in EtOH/H2O mix.

Im sure I will think of something but any suggestions would be great,

Naf1 · « **Reply #25 on:** October 22, 2009, 04:58:04 AM »

Well the acetaldehyde can be distilled at room temp (nearly), methanol and acetic acid are miscible so thats a pain in the ass. If you need quantification before going to the trouble of separation, to see how much you have in solution you just need a small sample of the material and use simple titration. Here is a good straight forward write up;

http://sharebee.com/4be20df4

Sedit · « **Reply #26 on:** October 22, 2009, 05:12:58 AM »

Titration is no problem at all and normaly I do a true titration before proceeding to an A/B, quantify anything, ect... I want to know my yeilds without wasting a lot of solution and titration will be the best way. When most say titration they mean just dump acid on base until neutral ect.... Not me, I do that shit right even if it is getto style with an eye dropper and not a burret. I know what im dealing with far before I attempt to change the PH of a solution like everyone should.

Do you know if EtOH and AcOH form an azeotrope off hand? I have feeling that will be my main problem by far if it does form a binary distillate which im pretty sure it does at some concentration. The Acetaldahyde seems to linger as well so I may wish to remove this some other way then distilling but thats yet to be seen.

Naf1 · « **Reply #27 on:** October 23, 2009, 01:09:23 AM »

The acetaldehyde should be able to be oxidized in the open air to yield more acetic acid. And ethanol can also be fermented to produce acetic acid, could you not put a couple of drops of naturally fermented vinegar in? to add a culture of acetic acid bacteria? then ferment (culture the bacteria like a brewing kit, should convert the ethanol that would be otherwise painfull to remove) Or is the concentration too high aleady? Naturally fermented vinegar can get up to 20+% acetic acid so I would assume you could use the rest of the ethanol to produce acetic acid in situ.

Dehydration of acetic acid by azeotropic distillation
Patent 5160412
http://www.freepatentsonline.com/5160412.html
"Currently there are at least four commercial ways to manufacture acetic acid. The fermentation of fruit (apples) or wood waste are the oldest. The reaction of acetylene with water to form acetaldehyde followed by air oxidation is still in use. Fermentation of ethanol to acetic acid is used when cheap ethanol is available. The reaction of methanol with carbon monoxide in aqueous solution is currently in favor because of cheap methanol. The air oxidation of butane to give a multitude of products, approximately forty, including acetic acid is currently attractive. All of these processes present the problem of separating water from acetic acid. Acetic acid boils at 118° C., water at 100° C. but although these two do not form an azeotrope, they are far from being an ideal mixture. The separation of water from acetic acid by distillation becomes especially difficult at high concentrations of acetic acid."

Also concerning titration, you can buy great pH indicator drops for under $10. The ones you use for swimming pools, would be perfect for titration. You would just have to take a very small sample, add the specified amount of indicator and start titrating. You know the ones;

Sedit · « **Reply #28 on:** November 17, 2009, 11:25:06 PM »

I got bord today and decided to try extraction of a 5% solution and chronical how it went. This is pretty much a cross post from what I just posted over at SciMad as well but I wanted to stimulate some discussion in this area and prepare to wrap it up sometime soon and place a PDF of all the experiments in the Publication section here. I will wait till I get my camera back because its on vacation right now with out me. I also want to have more success with the oxidation of EtOH before putting it altogether in one neat package.

Its a shitload of bulk but one could yeild 150ml or more from a gallon of 5% Vinegar and when compaired side by side Im not sure which is more of a pain in the ass, converting it all to Sodium acetate or just boiling salt and vinegar and tossing in some IpOH.

Materials
300ml 5% AcOH Saturated with NaCl.
70ml of 70% IpOH saturated with NaCl.

Procedure
Mixing of the two solutions showed no seperation of layers and after extra NaCl was added it still showed only slight signs of seperation.
MgSO4·7H2O was employed to further saturate the solution some more to aid in seperation. Obviously Anhydrous MgSO4 is more desirable but I used it all up and have not made more yet.
This proved effective and approximately 20ml of IpOH/AcOH seperated out of the 370ml mother liquor.

Mild tragedy strikes as 1 single drop of water fell into the 20ml after washing the other glassware and having a single drop fall into the solution. Should not be to much of an issue though considering that it should form an azeotrop with the IpOH and leave as im burning it off.[note 1]

I ignited the 20ml in a Stainless Steel container nestled in an icebath and allowed it to burn out(I feel a bit premature due to the wind)to yeild 7.5ml of slightly yellow liquid with faint hint of IPA.
This was placed in the freezer till chilled to no avail so it was once again taken outside and ignited.
This left me with a mixture that would no longer ignite at about 4ml of now much darker colored liquid.
Placing this in the freezer for only a couple minutes it was obviously much thicker consistancy then before and was simular to thin cough medicine or a thick sugar solution clinging to the sides of the test tube.
It still failed to crystalize on refridgeration.[note 2]

Notes
1: This is obviously not the best way to go and distillation is the prefered methods but Im just running a fun small test and did not feel like getting that involved. Plus it proves a point in that it will cease to ignite once the IPA leaves the system.
2: I would thing it be prudent to add anhydrous MgSO4 and filter prior to distillation.

Discussion:
Well it all pretty much came out of a fit of bordem since I was off work and had the house to myself for a change which left me with an itching desire to do something but since I live in bumblefuck without a store to even go to for a few miles I decided to see what I could play with. I wanted to see if it can be done and to what effect could be yeilded from such a dilute solution. 4ml of not quite anhydrous, or more probable tainted with IPA, Acetic acid sounds pretty bad but basing it more on the idea of how much a given amount of IPA will extract for a given volume does not work out extremely bad given the extreme dilution of the starting solution. Also since only a single extraction instead of the prefered two maybe three shown from previous experients means yeilds could atlest double if not more. I will more then likely not partake in another attempt to extract such a dilute solution again but I do feel confident from the experiment and those prior that a bottle of IPA and a gallon of 5% could yeild about 150ml of Glacial acetic acid if one where determined enough. I perhaps will attempt this one day just for shits and giggles but more then likely not for a while since I want to focus more on concentrated solutions.

Sedit · « **Reply #29 on:** June 11, 2010, 04:34:12 PM »

Running 2500ml of 5% AcOH with 250ml of 70% IpOH. Using MgSO4 to saturate the solution but having issues doing so.

marakov · « **Reply #30 on:** June 11, 2010, 09:16:03 PM »

Quote from: Vesp on September 22, 2009, 10:59:12 PM

Iron reacts with acetic acid.. so don't add iron, unless you want iron acetate - which I believe hydrolysis into acetic acid over time and with exposure to oxygen and water.

Fe/GAA is a well known method of reduction for a nitropropenes.

This is a good topic. Thanks go to you Sedit.

headstrong · « **Reply #31 on:** June 26, 2010, 08:19:50 AM »

Concentrating GAA from vinegar can be done by freezing first before heating/boiling, so less AcOH vapor will be produced;
"The vinegar was placed into plastic
two liter pop bottles. A space was
allowed for the expanding ice, and
the bottles were placed for 24 hours
into the freezer. We can see here
that the mostly watery part of the
vinegar is frozen, while the acetic
part is not. We must keep in mind
that water has a higher freezing
point than acetic acid. This allows
for us the distillation of the acetic
acid from our vinegar through a
freezing method."
Complete procedure can be found here;
http://www.alchemywebsite.com/distillation_of_vinegar.html

And another way to remove water from (concentrated) AcOH,
"Sometimes azeotropes are useful in separating zeotropic mixtures. An example is acetic acid and water, which do not form an azeotrope. Despite this it is very difficult to separate pure acetic acid (boiling point: 118.1°C) from a solution of acetic acid and water by distillation alone. As progressive distillations produce solutions with less and less water, each further distillation becomes less effective at removing the remaining water. Distilling the solution to dry acetic acid is therefore economically impractical. But ethyl acetate forms an azeotrope with water that boils at 70.4°C. By adding ethyl acetate as an entrainer, it is possible to distill away the azeotrope and leave nearly pure acetic acid as the residue.[2]"
Taken from wikipedia, mentioned under paragraph "Use of azeotropes to separate zeotropic mixtures";
http://en.wikipedia.org/wiki/Azeotrope

Azeotrope AcOH with various solvent;
http://en.wikipedia.org/wiki/Azeotrope_%28data%29

Sedit · « **Reply #32 on:** June 26, 2010, 05:18:20 PM »

I noticed the azeotrope data for AcOH does not this one for EtOH is this correct? I have been trying to find this out since im producing my AcOH from oxidation of ethanol at the moment using nitric acid. I want to know what kind of loss to expect when distilling off any excess EtOH and acetaldahyde from the mixture.

I have never had much success with freezing to produce GAA but I think I know a good way to do it which I will explain later.

headstrong · « **Reply #33 on:** June 27, 2010, 08:13:10 AM »

Quote

I noticed the azeotrope data for AcOH does not this one for EtOH is this correct? I have been trying to find this out since im producing my AcOH from oxidation of ethanol at the moment using nitric acid.

I think they don't form binary azeotrope, both are important substance but the azetrope data never found. Nor in Azetropic Data Rhodium archieve although binary azeotrope of EtOH and AcOH are listed.

Quote

I want to know what kind of loss to expect when distilling off any excess EtOH and acetaldahyde from the mixture.

Only if Ethyl Acetate can be formed IMO.

Why not use Ethyl Acetate to Extract AcOH from salt? It doesn't take AcOH, form azeotrope with water, and more polar than DCM and diethyl ether.

lugh · « **Reply #34 on:** June 27, 2010, 05:21:34 PM »

Some information on this subject was posted in:

https://www.sciencemadness.org/talk/viewthread.php?tid=5528#pid62592

and

https://www.sciencemadness.org/talk/viewthread.php?tid=7775#pid88475

it's not cost effective to produce glacial acetic acid from white vinegar unless there's absolutely no possible way to buy it

Concentration by freezing and subsequent azeotropic distillation is the most effective combination of purification techniques in this circumstance

Alternatively one can basify with caustic soda and crystallize the sodium acetate; then distill that with sulfuric acid to get glacial acetic acid

Sedit · « **Reply #35 on:** June 27, 2010, 07:06:41 PM »

Quote from: lugh on June 27, 2010, 05:21:34 PM

it's not cost effective to produce glacial acetic acid from white vinegar unless there's absolutely no possible way to buy it

I agree that vinegar to GAA is not cost effective however the oxidation of EtOH just may be.
453gr of KNO3 = about $6.50 give or take.
946ml of Denatured EtOH = about $6.50
One liter of H2SO4 = 12$

Add all that up(something I haven't done yet

) and you could generate a good amount of AcOH for 26$. The main point will be to see how much EtOH 1 mol of nitric acid will oxidise.

This is where things get strange because one abstract I have read said to add the substate until NO₂ stops being generated. I have already reached over 50 grams of EtOH to 1 mol of HNO₃ and there is still emissions of NO₂ noted.

I generated my HNO₃ from H₂SO₄ and KNO₃. I added 20 grams of H2O to make things more fluid. The flask contains a slushy mix of Potassium sulfate and red Nitric acid at this point from over heating as the Sulfuric was added to the nitrate.This is a good thing in this reaction BTW since NO₂ aids in initiating the oxidation avoiding a hazardest runaway. Slowly I added 10 grams of EtOH ml by ml which is slightly more then the .2 mol the papers recommend. The reaction at first is very vigorous and may need cooling with a large evolution of NO[sub2[/sub]. Stirring made this worse so I stopped doing that and gave it time to run its course.

I decided to keep adding EtOH in 5ml portions until it appeared to stop reacting. It so far has not stoped reacting but has slowed down and I now add only 1 ml at a time. A spot test on the smell does not indicate the smell of EtOH and only a trace of actaldahyde while the smell of AcOH is very very strong. On top of that as the EtOH is added Potassium sulfate precipitates due to the alcohol yet now 50 grams of Alcohol later and a long reaction time the entire reaction has become MUCH more fluid assumingly due to K sulfates solubility in AcOH.

One of the papers I read suggest that HNO₃ is nothing more then a carrier of the oxygen since O₂ in the air can reoxidise NO₂ so this may explain why it appears that this is having a never ending ability to oxidise alcohol. Im going to do a few more test and cut the experiment here at 50grams of EtOH and work up to see what I got because its just speculation until I have pure AcOH.

By anymeans used though imagine how cheep GAA could be made if a quantative form of oxidation could be found cheep. 956ml of EtOH could very well make a large amount of AcOH.

lugh · « **Reply #36 on:** June 28, 2010, 02:04:56 AM »

Quote

By anymeans used though imagine how cheep GAA could be made if a quantative form of oxidation could be found cheep. 956ml of EtOH could very well make a large amount of AcOH.

Acetic acid has been manufactured industrially via oxidation of ethanol for many decades

It's generally done in the vapor phase using oxygen as the oxidant

A patent describing one industrial process for doing so is attached

Sedit · « **Reply #37 on:** June 28, 2010, 03:10:05 AM »

Ugg, I hate patent talk. So many words to say so little.

I have stayed away from vapor phase reactions for sometime because im a pussy and fear explosion and fire for sometime. This appears pretty mild and I might just have a crack at it. I love how they labled there yeild as nothing more then Copious. That leaves alot to the imagination and im going to have to do more research before attempting it.

I have considered Ketene as a very nice means of large amounts of GAA and more but this appears much more tame and I think I got what I need already to have a go at it sometime soon.

Sedit · « **Reply #38 on:** June 29, 2010, 06:06:56 PM »

The Nitric acid method has had success but how much success is yet to be determined although it appears to have gone great. I will produce a full writeup in the end but I have abit of odds and ends to do before I can release a full text.

I have decided to try vapor phase reaction so thank you Lugh. You will all be impressed by the simplicity of the design I am working on when it is complete. I have decided to fill 1/4 Cu tubing with a catalyst mad e from mixing Copper chloride solution with Kaoline and then firing it. Once fired it will covert the chloride to the oxide and I will grind the catalyst to the desired mesh size. A couple more soaks in Copper chloride solution to provide the most CuO I can on the catalyst then fill a 1 meter section of the copper tube with it loosely. The tubing will be coiled to the size of a common household electric oven burner allowing me to condense over 1 meter of reaction tube down to an area only abot 6 inches diameter and it will most certinely reach the desired temperatures once it is strapped to the burner with copper cire. For finer control of the temperature and eveness I will also place a mixture of Kaoline and fiberglass atop the coil to maintain temperature and control the heat input with a dimmer switch as I have done in the past.

I think this in the end will be a raving success as long as the catalyst holds up to the theory they give. The entire unit once tested for safety could fit on a benchtop with MUCH room to spare being that it will only take up a little more then a couple cubic feet while still allowing meters of catalyst contact.

Sedit · « **Reply #39 on:** November 26, 2010, 08:55:04 PM »

I think I have worked out the DCM extraction of acetic acid.

I mix the trihydrate of sodium acetate and heat it with Bisulfate. After it sits a while to ensure it all reacted it will normally be a thin slush using the trihydrate. After it sits for a couple days the formed sodium sulfate sucks up most of the water but I have been adding MgSO4 to dry it better. I toss all this in a blender(soon its gonna be a bucket) and add a shitload of DCM. This is hard to filter right so I found best bet is to use a rag like a cheese cloth and then ring it all out. Add more DCM and do it again. Add more MgSO4 to the filtered solution till it shows complete dryness then run it thru a final filter and distill on a warm water bath. Whats left over froze over almost instantly and thats before I have even distilled the left over AcOH so the impure stuff is dry enough to be considered glacial.

Sounds complicated but its really not and it will scale even better then any other at home GAA method I can think of producing faster results. I do fear a bit of AcOH is comming over with the DCM though but if thats true I will find a way to recycle it.

Author Topic: Glacial acetic acid from aq solutions (Read 779 times)

Sedit

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Douchermann

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Naf1

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Naf1

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headstrong

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lugh

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lugh

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