Sciencemadness Discussion Board

OTC glacial acetic acid need help

LD5050 - 29-7-2017 at 07:18

I'm looking to make some otc GAA I have found a few methods on YouTube and stuff but it seems they don't get actual GAA and rather just concentrated AA. I was thinking g of getting sodium acetate from nuetrilizing vinegar and evaporating off the water but I read somewhere getting the sodium acetate from ethyl acetate might be better? Any body familiar with this process?

I know that I'll need anhydrous sodium acetate and 98% sulphuric acid. I plan on taking the sodium acetate and drying it in the oven but I heard it usually carmalizes the sugars that are in the product making it impure. I also plan on distilling drain cleaner to obtain the 98% H2SO4.

What is the best way to go about making otc glacial acetic acid? Will the method I mentioned work? I also have some acetic anhydride so maybe after I distill the sodium acetate and h2so4 together if I add some acetic anhydride it will remove the remaining water? But how much do I add? Do I reflux after audition or just add and stir?

Any help would be great.

XeonTheMGPony - 29-7-2017 at 07:37

I made my glacial as followes:

Acetone free nail polish remover: Distill 3 bottles the waste fractions will fill one bottle, distill again tighten the temp of the fraction down more, then finally distill a 3rd time over anhydrous magnesium sulfate, oven dry the receiving flask and precharge with some magnesium sulfate as well.

Set aside the triple distilled Ethyl Acetate with a stopper

Prep your boiling flask and condenser for reflux, dry thoroughly (I oven dried mine)

Measure out the hydroxide charge based on your ethyle acetate.

(If you own a dehumidifier now be a good time to let it run in your lab over night befor this part!)

Load into the boiling flask while still warm, promptly attach your reflux condenser (Which should have coolant running through it and be cool at this point with the male end lubricated) and add the cooled Ethyle Acetate leaving behind the sulfate of magnesia.

Allow it to do its thing with no added heating (Have a bowel of ice water to cool the flask if the dissolution of the hydroxide gets too vigorous)

Once fully dissolved and stable temp is reached heat to a steady reflux then leave it be for a couple hours or better.

During this time set up a new distillation apparatus after the thoroughly drying it out. if need be concentrate your Sulfuric acid during the reflux time, Set aside the acid in a very well sealed container.

Reset distillation rig, distill off all the ethanol, add an excess of acetic acid to the remainder to fully remove any sodium hydroxide, dehydrate by air then microwave to dehydrated state. Now at this point you can recrystallize in methanol or ethanol, I didn't bother with either first run.

Add the microwaved anhydrous sodium acetate to the distillation flask whilst hot from drying, allow to cool to room temp well sealed.

Take your fresh clean and concentrated sulfuric acid and chill in the fridge while you do the above prep work.

Once every thing is set up and your condenser is running and cool add the acid to the acetate charge and allow to react under its own energy, again when it reaches a state of rest slowly ramp up heat till distillate comes over.

Once don take the distillate flask and seal and place in the fridge till it crystallizes.

Place up side down with out the stopper and allow it to slowly warm up to 16c allowing any thing that melts to drain into a beaker.

That's how I separated out the concentrate from the glacial.

NOTE:

I ended up with allot of char in the boiling flask in the final run, after doing a recrystallization of my acetate I found some form of white goop left over as a small fraction, So I would recrystallize my Sodium Acetate in methanol next time round.

note 2:

The more you take the time to distill the precursors better the resualt from the get go, and as a side benefit you end up with anhydrous pure ethanol from the above method, very use full in the lab!

Note 3:

If your first run doesn't work out do not fret as the concentrated acetic acid will be needed for the next runs any ways so no matter what you win on time spent! Took me 3 runs befor I got good solid glacial.

[Edited on 29-7-2017 by XeonTheMGPony]

karlos³ - 29-7-2017 at 07:43

You have Ac2O, no? You mention it in another thread.
Are you really that determined to make glacial AcOH out of sodium acetate, because it would be very easy from Ac2O on?
After hydrolysis of some quantity of it, you can even make more absolute GAA by adding a tiny amount of Ac2O to it. And then freeze it for further purification.

Corrosive Joeseph - 29-7-2017 at 07:56

Handy table for anyone attempting GAA.............

http://askavantor.force.com/articles/FAQ/Freezing-Points-of-...


/CJ

LD5050 - 29-7-2017 at 08:27

Awesome write up Xeon I will defiantly give this a try thank you very much writing this up very helpful.

As for hydrolising acetic anhydride into GAA how would one do this? How much water does one add?

XeonTheMGPony - 29-7-2017 at 08:39

No prob there!

Oh and don't waste time trying to re distill from sulfuric acid to concentrate it! all you end up is with acetic acid just much less and allot of char!

Was a waste of time.

I plan to make a Ketene generator to concentrate my current stock of near glacial acid (The stuff that melted off as it was warmed very slowly to 16c) and eventualy to acetic anhydride.

karlos³ - 29-7-2017 at 10:25

You would add one mole acetic anhydride to one mole H2O, to result in two molecules of acetic acid.
Since I know you´re pretty new, I made a quick calculation:
- 10,209g of Ac2O(0,1mol) is reacted with
- 1,8g of dH2O(0,1mol), which results in(of course)
- 12g of AcOH(0,2mol). To make sure it is as waterless as possible, add a tiny bit of anhydride

clearly_not_atara - 29-7-2017 at 12:04

Sodium diacetate is OTC as a salt-and-vinegar flavoring. It's also easier to dry the diacetate than the monoacetate according to everything I've read.

Simply heating the diacetate with an acidic salt like NaHSO4 or NaH2PO4 should work, no?

Corrosive Joeseph - 29-7-2017 at 12:15

Using anhydrous mono-acetate - "Make Glacial Acetic acid using Sodium bisulfate (NaHSO4)"
https://www.youtube.com/watch?v=QQWvgLxtldc


/CJ

Corrosive Joeseph - 31-7-2017 at 18:29

Just found this while searching something completely different.........

Hydrolysis of acetic anhydride - Kennedy Joseph Previté Orton and Marian Jones

J. Chem. Soc., Trans., 1912,101, 1708-1720


Old Skool Attached -


/CJ

Attachment: orton1912.pdf (758kB)
This file has been downloaded 135 times


JJay - 1-8-2017 at 00:28

I found this practically ancient method while I was searching for something completely different:

A practical treatise on the manufacture of vinegar and acetates, cider, and fruit-wines; preservation of fruits and vegetables by canning and evaporation ..
by Brannt, William Theodore, 1844- ed


Untitled.png - 419kB

Apparently in olden times they prepared glacial acetic acid by first distilling acetic acid from anhydrous calcium chloride and then again from anhydrous sodium acetate, further purifying it by fractional freezing.

It's been said elsewhere on this board that copper sulfate and magnesium sulfate can be used to dry acetic acid, but I haven't seen a good writeup on either.

I'm not sure what to think of the distillation of 100 parts sodium acetate with 9 1/2 parts of sulfuric acid discussed in the document above. Those don't seem like the right ratios.... Perhaps it is a typo?

LD5050 - 1-8-2017 at 15:51

Karlos, I tried making the GAA from acetic anhydride. I used the amounts you provided and after mixing and diving the AA time to absorb the water I place the RBF with a stopper on top in the refrigerator and then also the freezer to see if it would freeze like GAA does when introduced to cold temps. I never got crystallization tho so I added 4-5ml more of GAA and still no crystallization. What is going on here, should I add more GAA?

JJay - 1-8-2017 at 15:59

Perhaps your acetic anhydride is partially hydrolyzed. Why did you add GAA when you didn't get crystallization?

You really need to learn how to do this stuff: https://www.youtube.com/watch?v=XnfATaoubzA

LD5050 - 1-8-2017 at 16:48

I'm sorry I meant I added more acetic anhydride*****

karlos³ - 1-8-2017 at 17:59

Yeah you should really learn to proper calculate stöchiometric amounts.
If you have a mixture, you will probably never get it to crystallise, considered the very low melting point of acetic anhydride and composition of the mixture.

The 4-5ml of Ac2O you´ve added ruined any known properties of the mixture, now you´ve got something you can only assume what it is exactly composed of.
4-5ml is way to much, when I said add a tiny amount Ac2O after hydrolysis, I meant somthing like just a drop, maybe two.

Still tho, your mixture is mainly AcOH(=GAA) now, mixed with the 4-5ml Ac2O(at least), which is why it wont freeze.
The mp of Ac2O is -73°C, so adding more Ac2O to the AcOH/Ac2O will of course not induce any kind of crystallisation.
Water will do that instead, but only if its the correct stöchiometric amount.
Substance mixtures usually don´t have the same melting point as the pure chemical itself, that is in fact one of the properties we use to characterise and thus differentiate substances from each other.

If you want precise results, you have to work precise, this isn´t like baking a cake, where you use the quantities as some sort of nonbinding recommendation, or even mix everything together solely by instinct.
Then it really is no surprise that it didn´t worked properly.

And another advice: if you keep proper documentation of your work, then you could just have looked how much Ac2O you´ve added in detail, thus be enabled to add the correct amount of H2O, and convert the whole mixture into GAA/AcOH.
Make it a habit, as it can help to correct many accidental failures you´ve made, like demonstrated here.

Sedit - 1-8-2017 at 22:14

I have stated it many times here and dont know why ots not more common but just add DCM to we acetic acid and add magnesium sulfate till it is dry, it filters quickly and easy and the DCM distills with no problem leaving GAA that crystalizes at normal room temperature and technical y does not need and distillation except to fully purify the final product. It's very easy with 100percpercent yeild starting with acid and acetate.

JJay - 1-8-2017 at 23:34

Quote: Originally posted by Sedit  
I have stated it many times here and dont know why ots not more common but just add DCM to we acetic acid and add magnesium sulfate till it is dry, it filters quickly and easy and the DCM distills with no problem leaving GAA that crystalizes at normal room temperature and technical y does not need and distillation except to fully purify the final product. It's very easy with 100percpercent yeild starting with acid and acetate.


That's a very interesting idea. I think I might give it a try....

XeonTheMGPony - 2-8-2017 at 06:43

Well tested drying with magnesium sulfate and distilling, was crappy, Now testing Calcium chloride and this seems to be the winner.

Will be distilling some DCM out of stripper soon so will give that a shot as well.

Got every thing I need to Make SO3 so next acetic acid run will be very dry!

LD5050 - 2-8-2017 at 07:43

Quote: Originally posted by karlos³  
Yeah you should really learn to proper calculate stöchiometric amounts.
If you have a mixture, you will probably never get it to crystallise, considered the very low melting point of acetic anhydride and composition of the mixture.

The 4-5ml of Ac2O you´ve added ruined any known properties of the mixture, now you´ve got something you can only assume what it is exactly composed of.
4-5ml is way to much, when I said add a tiny amount Ac2O after hydrolysis, I meant somthing like just a drop, maybe two.

Still tho, your mixture is mainly AcOH(=GAA) now, mixed with the 4-5ml Ac2O(at least), which is why it wont freeze.
The mp of Ac2O is -73°C, so adding more Ac2O to the AcOH/Ac2O will of course not induce any kind of crystallisation.
Water will do that instead, but only if its the correct stöchiometric amount.
Substance mixtures usually don´t have the same melting point as the pure chemical itself, that is in fact one of the properties we use to characterise and thus differentiate substances from each other.

If you want precise results, you have to work precise, this isn´t like baking a cake, where you use the quantities as some sort of nonbinding recommendation, or even mix everything together solely by instinct.
Then it really is no surprise that it didn´t worked properly.

And another advice: if you keep proper documentation of your work, then you could just have looked how much Ac2O you´ve added in detail, thus be enabled to add the correct amount of H2O, and convert the whole mixture into GAA/AcOH.
Make it a habit, as it can help to correct many accidental failures you´ve made, like demonstrated here.


I should have been more specific in saying that I added a total of 3-4 ml more of AA. At first after mixing the correct amount I placed in the fridge and when it didn't solidify I added 1-2 drops more of AA put back in the fridge and when it still didn't solidify I continued to do this until a total of 3-4 ml was added.

clearly_not_atara - 2-8-2017 at 11:10

Feels kind of silly to recommend it but if you were to add e.g. zinc to your acetic acid it will dissolve and the salt will form hydrates that dehydrate it completely. You can't over-dehydrate by this method, although you will lose some acetic acid to the zinc. Activated aluminum probably works even better.

Be aware that GAA is hygoroscopic.

But seriously, people, look on the ingredients of a bottle of "salt and vinegar" flavor at the grocery store sometimes. I'm not making this up. And it is -way- more concentrated than liquid vinegar.

[Edited on 2-8-2017 by clearly_not_atara]

karlos³ - 2-8-2017 at 12:51

Damn LD, I hope you haven´t discarded the hydrolysis experiment... you should, even with the lack of precise notes about the quantities added, be able to make some AcOH of above 90% just by carefully "fiddling around" with water addition...
Don´t know if you need only the glacial AcOH or if super concentrated one suffices as well, but it would be a shame anyway to throw away what you´ve produced there.

JJay - 2-8-2017 at 13:02

At this point, probably your best bet is to titrate your acetic acid/acetic anhydride mixture and also to titrate your acetic anhydride to determine concentration/purity. Then you can determine exactly how much acetic anhydride or water to add to the mixture to obtain GAA.

LD5050 - 2-8-2017 at 13:33

No karlos I did not throw away the now unknown mixture that I have but it is only a tiny amount and I have a large amount of acetic anhydride to play with so I probably will just get rid of it and start over.

XeonTheMGPony - 2-8-2017 at 17:26

CaCl seems to be the winner after sitting for the day a noticeable increase in viscosity Going to let it sit longer then decant to another beaker with fresh CaCl then distill and see what happens at 15c

XeonTheMGPony - 26-8-2017 at 08:42

FAILURE!

After siting for several weeks over calcium chloride I ended up with a viscus fuming fluid.

I loaded it into a 250ml flask and then attached a 300mm fractional column and started slow heating, during this I got white fuming from the vent.

I suspect I ended up with HCl and Calcium Acetate, I recovered some Acetic acid + water :(

So I would not recommend drying with CaCl