Sciencemadness Discussion Board

Glacial Acetic Acid from Sodium Bisulfate + Sodium Acetate - No Yield?

LuckyWinner - 23-6-2022 at 08:00

1.
Sodium Bisulfate 35g sourced from a 'Pool Ph down' article.
(mol excess of Sodium bisulfate was recommended by 1 youtube vid)
Was put in oven at 150C to dehydrate for ~1h.
it formed a liquid puddle which crystallized into a hard rock upon cooling.
rock was grinded up in coffee grinder into fine powder.


2.
Sodium Acetate 20g, prepared by mixing sodium bicarbonate (pharma grade)
with distilled white vinegar 20%.
1:1 mol ratio
then put in oven at 150C till it crystallized out.
ran through a coffee grinder and dried again.
fine dry white powder obtained.


3. both powders are manually mixed together inside a beaker for 1 minute with a spatula.
then placed in RBF, heat was steadily increased up to ~300C...


OBSERVATION:\
-----------------------
powders did not liquidize, stayed in the same shape the whole time.
a hazy cloud formed and condensed into a couple ml of hazy liquid.
very low yield compared to powders used.

product was added to baking soda and fizzled for several minutes.

whats the problem?



[Edited on 23-6-2022 by LuckyWinner]

clearly_not_atara - 23-6-2022 at 09:09

The problem is that your salts didn't melt. Two chemicals can't react if they aren't touching each other.
Quote:
The single most important condition for a successful synthesis is good mixing
- Nicodem
Sodium bisulfate melts at 315 C, sodium acetate at 328 C, while potassium bisulfate melts at just 195 C. I thought sodium nitrate might help but that only brings the mp down to 308. You either need to use potassium or go a little hotter.

LuckyWinner - 23-6-2022 at 13:17

Quote: Originally posted by clearly_not_atara  
The problem is that your salts didn't melt. Two chemicals can't react if they aren't touching each other.

Quote:
The single most important condition for a successful synthesis is good mixing
- Nicodem
Sodium bisulfate melts at 315 C, sodium acetate at 328 C, while potassium bisulfate melts at just 195 C. I thought sodium nitrate might help but that only brings the mp down to 308. You either need to use potassium or go a little hotter.


thanks, you are right.
upon cranking the hotplate to full power I got the powders forming a uniform cake...
but more heat is needed...

i guess a cooking hotplate or a high temperature heating band a la 'nurdrage sulfuric acid distillation' is necessary.

[Edited on 23-6-2022 by LuckyWinner]

Rainwater - 23-6-2022 at 14:04

https://www.google.com/search?q=alcohol+burner+temperature

clearly_not_atara - 23-6-2022 at 20:18

^the first few results of that Google search are quite misleading! The adiabatic flame temperature of ethanol is a searing 1800 C, but this is only achievable when ethanol vapor is combined with oxygen in the ideal fuel/air proportion for combustion. However, a flame above liquid alcohol reaches a much milder temperature of just 850 C:

https://www.researchgate.net/figure/The-flame-temperature-di...

PirateDocBrown - 23-6-2022 at 22:54

Anhydrous sodium bisulfate doesn't melt at 315. It decomposes at that temp.

Why are you dehydrating it? It will melt as the monohydrate at a much lower temperature. It will then dissolve the acetate.

Hydrous acetate is a trihydrate, so you will have 4 waters for each molar equivalent of acid.

But sodium sulfate, the end product, prefers to be a decahydrate. So it will try to hang onto water pretty hard.

You will get pretty pure acetic acid just using hydrous salts.

But don't worry! You can fractionally distill acetic acid. It doesn't form an azeotrope with water.

LuckyWinner - 24-6-2022 at 01:01

Quote: Originally posted by PirateDocBrown  
Anhydrous sodium bisulfate doesn't melt at 315. It decomposes at that temp.

Why are you dehydrating it? It will melt as the monohydrate at a much lower temperature. It will then dissolve the acetate.

Hydrous acetate is a trihydrate, so you will have 4 waters for each molar equivalent of acid.

But sodium sulfate, the end product, prefers to be a decahydrate. So it will try to hang onto water pretty hard.

You will get pretty pure acetic acid just using hydrous salts.

But don't worry! You can fractionally distill acetic acid. It doesn't form an azeotrope with water.




my source for this experiment
canadian chemist
https://www.youtube.com/watch?v=ZuZTujNV84c

1.at the beginning he says that its very difficult to frac distill acetic acid and water to get GAA...

2.directly after he says you need anhydrous sodium acetate and anhydrous sodium bisulfate
cause any water present in these 2 will lower the GAA concentration in the final product...


3.freezing the acid to purify it is also limited to a max 50% concentration...


Google:
'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.'


I want to make glacial acetic acid (waterfree acetic acid)


if this is all wrong then what is the optimal way WITHOUT using 98% sulfuric acid?




SM WIKI:

Sodium Bisulfate
'Melting point 58.5 °C (137.3 °F; 331.6 K) (monohydrate)
315 °C (599 °F; 588.15 K) (anhydrous, decomposes)

Boiling point Decomposes '

[Edited on 24-6-2022 by LuckyWinner]

PirateDocBrown - 24-6-2022 at 07:42

First thing I'd try is anhydrous calcium sulfate for a few days, to the wet acid. Then, the distillation from a boiling flaks with fresh CaSO4. And a really tall column.

Tsjerk - 24-6-2022 at 12:37

Quote: Originally posted by PirateDocBrown  
Anhydrous sodium bisulfate doesn't melt at 315. It decomposes at that temp.

Why are you dehydrating it? It will melt as the monohydrate at a much lower temperature. It will then dissolve the acetate.

Hydrous acetate is a trihydrate, so you will have 4 waters for each molar equivalent of acid.

But sodium sulfate, the end product, prefers to be a decahydrate. So it will try to hang onto water pretty hard.

You will get pretty pure acetic acid just using hydrous salts.

But don't worry! You can fractionally distill acetic acid. It doesn't form an azeotrope with water.


Sodium sulfate doesn't hold on to water well at elevated temperatures. The temperatures needed to to distill the AA will effectively dehydrate the sulfate.

LuckyWinner - 25-6-2022 at 01:37

Quote: Originally posted by Tsjerk  
Quote: Originally posted by PirateDocBrown  
Anhydrous sodium bisulfate doesn't melt at 315. It decomposes at that temp.

Why are you dehydrating it? It will melt as the monohydrate at a much lower temperature. It will then dissolve the acetate.

Hydrous acetate is a trihydrate, so you will have 4 waters for each molar equivalent of acid.

But sodium sulfate, the end product, prefers to be a decahydrate. So it will try to hang onto water pretty hard.

You will get pretty pure acetic acid just using hydrous salts.

But don't worry! You can fractionally distill acetic acid. It doesn't form an azeotrope with water.


Sodium sulfate doesn't hold on to water well at elevated temperatures. The temperatures needed to to distill the AA will effectively dehydrate the sulfate.



what is the 'proper way' to make GAA from sodium acetate and sodium bisulfate?
(glacial acetic acid 100% acetic acid, waterfree)

I am confused now after all of these responses.

LuckyWinner - 18-8-2022 at 02:38

still nobody?

how does one make GAA
from sodium acetate and sodium bisulfate?
(glacial acetic acid 100% acetic acid, waterfree)

Tsjerk - 18-8-2022 at 07:24

Do you have a source that says you can? I probably read this thread back then but didn't respond because I don't know.

Now I read back the whole thing, my guess is that unless you know someone actually succeeded, you can't. Many people will have tried.

I definitely think you can get acetic acid when you use hydrated salts, but the problem is; that will give you acetic acid with water. The salts won't stick to the water at the temperatures they melt at.

Distillation afterwards, as you probably know, won't be practical either. Although concentrated sulfuric acid can be used to remove the water. There has been a thread lately, a couple of weeks ago at most, where someone asked how GAA is made in industry, it was something with big scale and CO.

[Edited on 18-8-2022 by Tsjerk]

teodor - 18-8-2022 at 08:54

Waterfree acetic acid is not the same as glacial acetic acid, LuckyWinner.
Glacial acetic acid can still contain 0.5% of water or more. It still can ruin experiments which require water-free acid.
If I properly remember the practical way to make 99.5% acetic acid in a laboratory is to use ethyl acetate to make azeotrope with water. Definitely the topic was already discussed here.
If you want to get glacial acetic acid starting from hydrated sodium acetate and bisulfate then the practical way, I think, is to distill diluted acid first, then to concentrate it with a fractionating column, then by azeotrope method (or fractinal crystallization).

If the purpose of your experiment is to look what you can get from anhydrous salts then use glacial acetic acid or glacial acetic acid + ethanol mix as a solvent to start the reaction.

To get water free acetic acid you need to free it from water either with a help of acetic anhydride or anhydrous cloride (TiCl4, SiCl4) depending on what could be possible contamination. Other ways to remove that 0.5% of water are unpractical.

LuckyWinner - 21-8-2022 at 01:37

Quote: Originally posted by Tsjerk  
Do you have a source that says you can? I probably read this thread back then but didn't respond because I don't know.

Now I read back the whole thing, my guess is that unless you know someone actually succeeded, you can't. Many people will have tried.

I definitely think you can get acetic acid when you use hydrated salts, but the problem is; that will give you acetic acid with water. The salts won't stick to the water at the temperatures they melt at.

Distillation afterwards, as you probably know, won't be practical either. Although concentrated sulfuric acid can be used to remove the water. There has been a thread lately, a couple of weeks ago at most, where someone asked how GAA is made in industry, it was something with big scale and CO.

[Edited on 18-8-2022 by Tsjerk]


several youtube videos claim you can make GAA from these 2 compounds.

what type of acetic acid concentration are you able to achieve with
Sodium Bisulfate + Sodium Acetate?


what DIY home version is the best to make GAA?

Tsjerk - 21-8-2022 at 08:16

Do those people on YouTube show, by actually measuring it, the concentration of their product? Or do they get a liquid and then just claim it is GAA?

The way to do it is by adding the minimum of water to the bisulfate/acetate to get a product, and afterwards drying the product with a drying agent, MgSO4 for example. This salt doesn't lose all its water of hydration upon heating to 120 ish degrees.

Edit: I watched the video you posted, either you didn't heat your salts hard enough, or what they produce is not dry.

Edit: sodium bisulfate decomposes at those temperatures, and guess what it loses when it does: water. The potassium salt also doesn't melt, it just decomposes at a lower temperature.

[Edited on 21-8-2022 by Tsjerk]

LuckyWinner - 27-9-2022 at 12:42

Quote: Originally posted by Tsjerk  
Do those people on YouTube show, by actually measuring it, the concentration of their product? Or do they get a liquid and then just claim it is GAA?

The way to do it is by adding the minimum of water to the bisulfate/acetate to get a product, and afterwards drying the product with a drying agent, MgSO4 for example. This salt doesn't lose all its water of hydration upon heating to 120 ish degrees.

Edit: I watched the video you posted, either you didn't heat your salts hard enough, or what they produce is not dry.

Edit: sodium bisulfate decomposes at those temperatures, and guess what it loses when it does: water. The potassium salt also doesn't melt, it just decomposes at a lower temperature.

[Edited on 21-8-2022 by Tsjerk]


or use the hydrated sodium bisulfate directly from the store and add it to your anhydrous sodium acetate?

add dry MgSO4 , epsom salt, to distillate and very gently distill off the GAA ?
you should not crank up the hotplate to full blast but slowly raise it and stop when there is still some liquid left?

to determine MgSO4 amount needed to dehydrate AA, add MgSO4 to acetic acid till newly added MgSO4 stays crystalline then start the distillation?

[Edited on 27-9-2022 by LuckyWinner]

Chemgineer - 7-10-2022 at 06:06

I've made concentrated acetic acid from anhydrous sodium acetate and standard hydrated pool sodium bisulfate. I can confirm it was not GAA as it does not freeze when placed in a refrigerator. It is still quite potent though and painful to to nose when inhaled.

Organikum - 7-10-2022 at 11:23

If one heats orthophosphoric acid for a prolonged time to about 150°C it turns into a crystalline mass. This mass is as I believe composed of metaphosphoric polyacids or in short: Some shit you get when you heat H3PO4.
On addition of water this mass turns back to phosphoric acid. This takes quite some time but it happens.

Now we have something what looses water at 130°C+ and turns back to the old state on addition of water. GAA distills at 118°C the complete dehydration of H3PO4 is more near 150°C.

Sounds to me like there is a real chance this will work. Patience will be the key, I would expect a week at least to get near anhydrous, warming it up should help, 50°C maybe 80°C?

Also other organic acid anhydrides might be worth to be looked into, there are several which are not to hard to make and where the correspondending acid has a boiling point far enough from GAA to make separation by distillation possible.

That acetic acid is a bitch and cannot be dried by conventional ways is a dead beaten horse, the mentioning of MgSO4 in earnest was bewildering. Where is the inspiration? The outright crazy and/or insane suggestions?
The doors of registration should be opened at least as much as necessary to have some more slip through then now, in special some fringe personalities.

Tsjerk - 8-10-2022 at 02:03

Good to have you back Organikum, too bad you seem to have turned in a sour prick who needs to put in his political views every other post and uses personal attacks to make a point.

RU_KLO - 25-10-2022 at 10:15

Is it possible to remove last traces of water in a dessicator bag (anhydrous NaOH, anhydrous CaSO4).

Note: Im new in Chemistry, but used this process to remove water and cristallize reagents. Takes time (in weeks).

Used a lot of CaSO4, like a kilo for 30ml of solution. CaSO4 was heated in oven 3hs at aprox 200°





[Edited on 25-10-2022 by RU_KLO]

Polysialate - 25-10-2022 at 17:52

I wonder if this method could be improved by using an equimolar mix of sodium and potassium acetate instead of just sodium acetate? Both Na and K acetates have the issue that they only melt a few degrees shy of their decomposition temperature, and their decomposition produces water.

An equimolar mix formed by drying an equimolar aqueous Na/K acetate solution might result in a eutectic with a lower enough melting point that dry acetic acid is produced.