Sciencemadness Discussion Board

Puryfiing 99% denatured alcohol

Schleimsäure - 9-7-2021 at 09:07

So got myself another 2,5l of denatured 99% Ethanol.

New is, the alcohol thistime is not only denatured with 1% MEK and a few ppm Bitrex.
Bitrex can be get rid of with simple destillation. MEK with Hydroxylamine.

But thistime it reads also 1% IPA (which makes 101% but anyway).

Boiling point of IPA is much too close to Ethanol.

So no chance of getting rid of the IPA, I guess?

karlos³ - 9-7-2021 at 10:26

Ah the damn new EU laws... yeah, mucic acid, I stumbled upon this new adulterant too :mad:

They are even in the cheaper spiritus brands now... I loved to use the good old AHK spiritus in the clear bottle with the green cap... besides it getting almost twice as expensive very recently, now they added that crappy IPA to it.
I don't know either.

Just wanted to express my frustration about this new law as well.
PS: I remove MEK usually by refluxing with some NaOH, and then distilling the ethanol off, as the MEK will selfcondense in an aldol to a much higher boiling compound.

Tsjerk - 9-7-2021 at 11:46

What do you need the IPA seperated for? It should be fine for most purposes.

stamasd - 9-7-2021 at 11:58

Not a direct answer to the OP question, but bitrex/denatonium can be removed easily by treatment with an acidic ion exchange resin such as polystyrene sulfonate. It's cheap, fast and effective. It works because denatonium is a quaternary ammonium compound. Also, mucic acid should be just as easily to get rid of using a similar basic ion exchange resin.

[Edited on 10-7-2021 by stamasd]

Fulmen - 10-7-2021 at 01:59

Quote: Originally posted by karlos³  
mucic acid, I stumbled upon this new adulterant too


Wait, what? I can't find any references to that that, and it's supposed to be insoluble in alcohol. Either way it should be easy to remove by distillation.

[Edited on 10-7-21 by Fulmen]

karlos³ - 10-7-2021 at 02:50

The new adulterant I meant is the IPA, which
was formerly not in denat. alcohol here, it is now in use EU-wide.
Bitrex is easily removed via distillation indeed.

E: with "mucic acid", I spoke to the user Schleimsäure, which is the german word for mucic acid.
It is not in denatured alcohol :D
Sorry for the confusion :P

[Edited on 10-7-2021 by karlos³]

Fulmen - 10-7-2021 at 03:32

:D

Schleimsäure - 10-7-2021 at 07:40

Quote: Originally posted by Tsjerk  
What do you need the IPA seperated for? It should be fine for most purposes.


Sometimes you need pure EtOH. Also isn't it neat to have pure reagents?

Schleimsäure - 10-7-2021 at 07:42

Quote: Originally posted by karlos³  
Ah the damn new EU laws... yeah, mucic acid, I stumbled upon this new adulterant too :mad:

They are even in the cheaper spiritus brands now... I loved to use the good old AHK spiritus in the clear bottle with the green cap... besides it getting almost twice as expensive very recently, now they added that crappy IPA to it.
I don't know either.

Just wanted to express my frustration about this new law as well.
PS: I remove MEK usually by refluxing with some NaOH, and then distilling the ethanol off, as the MEK will selfcondense in an aldol to a much higher boiling compound.


Ja, didn't know it was new "EU law". Concerning MEK I used once also some NaOH. But hydroxylamine is the safer choice as far as I know, making the oxime of the MEK.

Schleimsäure - 10-7-2021 at 07:47

Found a very old source. They should have some "old stock".

https://www.aurelio-online.com/epages/61694983.sf/de_DE/?Obj...


5l for 19 EUR is also kind of ok in price.

EDIT: Spoke too soon, also with IPA already.

[Edited on 10-7-2021 by Schleimsäure]

Tsjerk - 10-7-2021 at 16:44

Quote: Originally posted by Schleimsäure  

Sometimes you need pure EtOH. Also isn't it neat to have pure reagents?


I have been looking around for ways to selectively oxidize secondary alcohols, but couldn't find much useful.

Schleimsäure - 10-7-2021 at 18:14

Most probably not worth the effort. In case you will have to pay the price for absolute ETOH, I guess.
But you are right oc, for many purposes den. EtOH is sufficient.

I think in France MeOH is still used to denature. That would be not suitable for certain fragrances things for example.

stamasd - 11-7-2021 at 04:39

It's weird when you think about it that they would use IPA as a denaturant. The purpose of the denaturants is to prevent people from drinking the alcohol and IPA is not much of a deterrent in that regard. It does not add any weird tastes, nor is it overly toxic.

Tsjerk - 11-7-2021 at 06:38

It does make any illicit liquor produced with it easily detectable.

syntheticvibes - 11-7-2021 at 13:27

Along the lines of this thread, I feel like I got cheated out of a good organic lab experience because of covid. For my own purposes, I have just over a gallon of 45-55% ethanol denatured alcohol with the other portion being methanol. Is a methanol denatured alcohol solution really that difficult to separate? I've read a source say they azeotrope and many others not make mention of it. Wouldn't a good fractioning setup work well?

Fyndium - 12-7-2021 at 20:51

What reactions would be such that 1% of IPA would be detrimental to their outcome? Just interested.

My common source for cheap otc EtOH has been contaminated with all other nasties along with MEK, but has been decent for all of my uses so far, so haven't complained. My go-to has been to stir it for few hours with 2-3% NaOH during which it turns tar black and then distill off the ethanol.

50% Methanol ethanol mix would seem somewhat uneconomical to separate, unless you have over 1m active reflux column, and even then most will consider it absolutely unsuitable for consumption of any sort. Reason methanol is verboten in EU is because alcoholics will consume cheap substitute alcohols due to high tax, and may not be too precise what they sip especially under influence. I actually think it's a good thing to keep it off as a denaturant, because it's purpose is to de-nature it to unpotable consistency so that anyone attempting to drink it will desirably puke it up at once, not to poison it by way that tastes exactly like the real thing but will burn off your eyes first and then kill you.

[Edited on 13-7-2021 by Fyndium]

SWIM - 12-7-2021 at 22:20

Quote: Originally posted by stamasd  
It's weird when you think about it that they would use IPA as a denaturant. The purpose of the denaturants is to prevent people from drinking the alcohol and IPA is not much of a deterrent in that regard. It does not add any weird tastes, nor is it overly toxic.


It also serves to remove water as a ternary azeotrope to give nice, dry denatured ethanol.

I used to get denatured ethanol that was 5% isopropanol, but fairly anhydrous.
This was in the USA, and the isopropanol was the sole denaturant.

I suppose you could rid it of isopropanol by adding water and boiling off that ternary azeotrope, but then it would need drying if you needed it anhydrous.

Hoffit - 13-7-2021 at 06:38

I think IPA is a pain to separate from ethanol. I can think of no conventional method that does it easily with typical hobby equipment. (That rules out stuff like rotating columns with hundreds of plates etc) I guess a large column with a huge reflux (perhaps more than once) could do the job very slowly (perhaps multiple very long distillastions). You're probably faster off making acetates, separating them and hydrolizing followed by distillation or whatever other reactions you may like.

Extractive distillation seems one method that can be used industrially but it is not very suitable for a hobby lab and batch jobs. Even with this method you may still need very large number of plates like 50 like estimated here https://scholarworks.montana.edu/xmlui/bitstream/handle/1/62...

Luckily I have available a windshield washing fluid concentrate that has only 1% MEK in it along with some easy to distill off surfactants, parfume and about 20-25% water. Dirt cheap too, something like €15 per 10 liters. Takes a while to distill a canister due to lots of water.

Fortunately slight impurities won't matter often. Even if you use it as a reagent, you still get only 1% of the wrong stuff. You rarely get 99% yield anyway. Isopropanol rarely destroys reactions where ethanol is ok.

If you really need ethanol without isopropanol, you are probably better off starting with something without IPA in it in the first place. IPA free drinkable alcohol is easily available but can cost quite a bit due to taxing.

karlos³ - 13-7-2021 at 08:09

Quote: Originally posted by Tsjerk  
It does make any illicit liquor produced with it easily detectable.

Yeah, I agree, that might have been their point with this addition.
Up until around ~1,5 years ago, I could distill the denat. ethanol (AHK Spiritus) that was sold for I think around 2,40€ back then, after refluxing with some sodium hydroxide, and after redistillation it smelled as clean as vodka.
A taste test confirmed cleanest ethanol as well :o :P

It was a good source for pure ethanol, and I can imagine some people with the facilities would be tempted to turn the cheap denat ethanol into taxed drinking ethanol(of which the denat. EtOH has merely 5% of its worth, before the recent inflation, making the whole process very worthy if you have huge distillation equipment for some reason).

Now that stuff stinks after IPA after the distillation, but of course it is still good to use it for almost everything.

Tsjerk - 13-7-2021 at 09:07

In the end, the purpose of denaturing alcohol is indeed not to make it undrinkable, the goal is to not lose taxes.

karlos³ - 13-7-2021 at 09:50

Yes, I would even think that is indeed one of the largest worries the states have.
Considered that the liquor tax is among petrol and tobacco taxes resulting in the highest incomes.

I would want to protect that source too, if it fills my wallet.
its was a bigger problem in the eastern european states, but since this is now enacted EU-wide.... we'll see.

Also, the denatured ethanol got much more expensive, is this the same in other EU countries?
It suddenly increased about 40% for the good denat. EtOH I usually buy(AHK Spiritus, as said), now it costs almost 4€.
And that can definitely not be explained with the recent addition of IPA!
Either its ripoff or inflation.

Oxy - 13-7-2021 at 09:50

If you want it really clean, have a time and will to distill it then maybe a sugar and turbo yeast are good option? Needs some time for the process and purification but in the end can be really clean

karlos³ - 13-7-2021 at 10:26

Yeah if its for the production of drinkable/clean ethanol, I heard good things from a friend who makes, what was it called... "poitin" I think?
True *** local whiskey is a clear liquid, i've been told.
A friend from europe told me that, local declaration... eh... maybe it was another name from another country? :P
But its just sugar, turbo yeast, distillation and no liquor tax.

Do swedes and danes do that too?
They brew to avoid the state liquor shops, thats known, but do they also moonshine?
And if, how do they call it?


Tsjerk - 13-7-2021 at 11:44

I heard moonshining is big in Scandinavian countries, I don't know how they call the process, but the liquor is called snaps. They use to bring their own snaps to parties as buying alcoholic drinks for many guests becomes expensive real fast.

Fulmen - 13-7-2021 at 11:53

It's a bit of a dying art most places I think, but there are always some that keep the tradition going.

Oxy - 13-7-2021 at 12:02

Quote: Originally posted by Tsjerk  
I heard moonshining is big in Scandinavian countries, I don't know how they call the process, but the liquor is called snaps. They use to bring their own snaps to parties as buying alcoholic drinks for many guests becomes expensive real fast.


I've read somewhere that in Norway(?) it can even bring some attention to buyer. Government agencies can even start procedures which may have severe consequences like separating from children when they think the alcohol intake is too much.
Norway has however really strange politics when it comes to children. I don't live there but I wonder if it's really such effective as their agencies want and if it really helps children instead of ruining them psychologically.

karlos³ - 13-7-2021 at 12:24

They call it "snaps"?
No doubt that stems from the same root as the german word Schnaps :o
Very interesting!

Schleimsäure - 13-7-2021 at 13:52

Quote: Originally posted by karlos³  

Either its ripoff or inflation.


Mix of both. Inflation is quite nasty with all the central banks "printing".

Mateo_swe - 17-7-2021 at 07:31

In Sweden we call homemade ethanol made for drinking "Hembrännt", hem=home, brännt=brewed, distilled.
In my youth i had a stainless distiller rig with 20L capacity.
I made the "Mäsk" with turboyeast + common sugar in 25L pails, it took 4-5 days something to be ready for the distiller.
After distilling, diluting to 40% and purification by activated coal it tastes almost nothing, just a warmth in the chest.
Way better than store bought vodka.
The secret to very good homemade ethanol is the quality of the activated coal.
I still have the stainless distilling rig somewhere but it hasnt been used for 15-20 years.
Maybe i could start using it for making absolute ethanol.
But how to get rid of the last 5% water, molecular sieves?

Tsjerk - 17-7-2021 at 14:29

Good idea to pick up a rig like that! I would start the drying with magnesium sulfate, you can distill off the ethanol as it loses only little water at those temperatures, or filter.

Better would be CaO though, when you use enough and distill the ethanol you will get anhydrous in one go.

Molecular sieves are nice, but I think they soak up a lot of solvent when used in amounts enough to dry > 0.1% water.

karlos³ - 17-7-2021 at 14:51

The 5% water can apparently be removed well with potash, K2CO3.
Although I never tried that.
If it isn't complete, which I doubt it is(but it works great to pull residual water from IPA for example), then you can employ mol sieves.
Distillation over CaO, as Tsjerk also said, is usually the standard method.

Such a large still! :o
That would bring customs for tax infringement on the plan here, if they would know... actually, only 500ml's is legally allowed to own without registration :o
But you don't require any registration for labglass, what I told the one or other moonshiner at some point, and a 20l flask from china isn't that expensive :P

Mush - 17-7-2021 at 16:03

Quote: Originally posted by Schleimsäure  
Quote: Originally posted by karlos³  
Ah the damn new EU laws... yeah, mucic acid, I stumbled upon this new adulterant too :mad:

They are even in the cheaper spiritus brands now... I loved to use the good old AHK spiritus in the clear bottle with the green cap... besides it getting almost twice as expensive very recently, now they added that crappy IPA to it.
I don't know either.

Just wanted to express my frustration about this new law as well.
PS: I remove MEK usually by refluxing with some NaOH, and then distilling the ethanol off, as the MEK will selfcondense in an aldol to a much higher boiling compound.


Ja, didn't know it was new "EU law". Concerning MEK I used once also some NaOH. But hydroxylamine is the safer choice as far as I know, making the oxime of the MEK.


Denatured Alcohol Not For Human Consumption EU regulation
Code:
https://ec.europa.eu/taxation_customs/denatured-alcohol-not-human-consumption_en


"Per HL of absolute alcohol

1L methyl ethyl ketone (a smelling agent)
1L isopropyl alcohol (a chemical analytical marker)
1gr denatonium benzoate (a tasting agent)

In a few Member States, there are varying combinations of the quantities of two of the three chemical agents, but all three chemical agents are present in all of the Member States "Euro" formulations for CDA."

EtOH forms a salt alcoholate with Calcium Chloride and Magnesium Chloride .


Attachment: Reaction of calcium chloride and magnesium chloride and their mixed salts with etoh.pdf (770kB)
This file has been downloaded 65 times

[Edited on 18-7-2021 by Mush]

Fyndium - 17-7-2021 at 23:01

Quote: Originally posted by Mateo_swe  
In Sweden we call homemade ethanol made for drinking "Hembrännt", hem=home, brännt=brewed, distilled.
In my youth i had a stainless distiller rig with 20L capacity.
I made the "Mäsk" with turboyeast + common sugar in 25L pails, it took 4-5 days something to be ready for the distiller.
After distilling, diluting to 40% and purification by activated coal it tastes almost nothing, just a warmth in the chest.
Way better than store bought vodka.
The secret to very good homemade ethanol is the quality of the activated coal.
I still have the stainless distilling rig somewhere but it hasnt been used for 15-20 years.
Maybe i could start using it for making absolute ethanol.
But how to get rid of the last 5% water, molecular sieves?


I have 50L DIY stainless steel boiler with 1500mm bokakob active reflux column. It can put out about 2 liters of azeotropic ethanol per hour, or without reflux it can strip at least 5 liters of 60-70%. The column attaches to the boiler with a standard flange and PTFE gasket. It is unsimple to get very good tasting vodka actually, and I must disagree that store bought vodka would be bad, because all of it is distilled to azeotrope in an ethanol plant in the first place, and the producers dilute and if necessary, filter it with carbon.

I have used my still a couple of times to strip clean ethanol and toluene: it is easier and a lot cheaper to buy 10 liter canisters of the stuff right away, and distill them clean at once. The ethanol consists only denaturants and detergents and comes clean over at 78C. Toluene, sold as paint thinner, contains mostly lighter fractions from 55C, and finally toluene fraction. The cuts are very clean and easy to make with that still.

Keras - 5-8-2021 at 02:28

Quote: Originally posted by Hoffit  
I think IPA is a pain to separate from ethanol. I can think of no conventional method that does it easily with typical hobby equipment.


Apparently, according to the excerpt attached below from the book Oxidation of Alcohols to Aldehydes and Ketones bleach or molecular chlorine is able to selectively oxidise secondary alcohols to ketones while primary alcohols are unaffected. Bromine can be used too, so a few drops of a bromine solution in DCM might do the trick.


Screenshot 2021-08-05 at 12.21.53.png - 297kB

Tsjerk - 5-8-2021 at 07:09

Quote: Originally posted by Keras  
Bromine can be used too, so a few drops of a bromine solution in DCM might do the trick.


According to the paper (and the excerpt) that only works in glacial acetic acid. Bromine and chlorine with ethanol and water give HBr/HCl and ethyl acetate. Without water you will halogenate the ethanol.

Attachment: stevens1980.pdf (461kB)
This file has been downloaded 39 times

[Edited on 5-8-2021 by Tsjerk]

Keras - 5-8-2021 at 07:46

Quote: Originally posted by Tsjerk  
Quote: Originally posted by Keras  
Bromine can be used too, so a few drops of a bromine solution in DCM might do the trick.

Without water you will halogenate the ethanol.

Oops. My bad. But that might suggest another way. Some sort of SN1 substitution which would favour the IPA over ethanol.

karlos³ - 5-8-2021 at 09:21

Maybe a weak oxidant, secondary alcohols are much easier oxidised to ketones than primary alcohols to aldehydes or even acids?

Always have to think of the oppenauer somehow, but I doubt that is possible here at all, but maybe there are modifications possible to achieve this?
No idea.
I though I'll mention it anways.

macckone - 5-8-2021 at 10:43

Removing isopropanol from ethanol is easiest via a chlorination with hydrochloric acid and zinc chloride.
Isopropanol chlorinates much more easily than ethanol.
But all of the ethyl chloride will distill off easily.
The much greater difference in boiling points will be easier to distill.
Ethyl Chloride (12C)
Isopropyl Chloride (36C)
Isopropyl Alcohol (80C for 91%)
Ethyl Alcohol (78C - azeotrope and pure differ in less than 0.2C)

Keras - 5-8-2021 at 11:03

Quote: Originally posted by macckone  
Removing isopropanol from ethanol is easiest via a chlorination with hydrochloric acid and zinc chloride.
Isopropanol chlorinates much more easily than ethanol.

So, yeah, that’s basically a SN₁ reaction.
The SN₂ mechanism for ethanol is slower?

Schleimsäure - 5-8-2021 at 11:14

Quote: Originally posted by macckone  
Removing isopropanol from ethanol is easiest via a chlorination with hydrochloric acid and zinc chloride.
Isopropanol chlorinates much more easily than ethanol.
But all of the ethyl chloride will distill off easily.
The much greater difference in boiling points will be easier to distill.
Ethyl Chloride (12C)
Isopropyl Chloride (36C)
Isopropyl Alcohol (80C for 91%)
Ethyl Alcohol (78C - azeotrope and pure differ in less than 0.2C)


Thanks, that is the way to go, I guess. And even economical since HCl and zinc chloride are cheap.

That means for me:
1. First refluxing with hydroxylamin to oximise the MEK.
2. Destilling, getting rid of the oxime and Bitrex.
3. Chlorinate the product with HCl and ZnCl2
4. Destill to separate pure EtOH from 3)

I got a 4l 3-neck, should be worth it.

The hydroxylamine is not the cheapest, but you don't need that much for that bit of MEK.

Thanks again.



[Edited on 5-8-2021 by Schleimsäure]

macckone - 5-8-2021 at 11:38

Keras,

Isopropanol converts via both sn1 and sn2.
With ethanol sn2 is more favorable but the ethanol replacement is less favorable in alcohols and OH is a poor leaving group.
The thermodynamics favor isopropyl chloride over ethyl chloride but not by much.
Both will boil off as they are formed at even modest heat with ethyl chloride boiling at 12C it boils off quickly.

The solution in question is supposed to be 99% ethanol so ultimately more ethyl chloride will likely form than isopropyl chloride even though the isopropyl chloride is more favorable there is less of it.

You are going to have the same problem with oxidizers as ethanol will oxidize to acetic acid just as isopropanol will oxidize to acetone. Both will be removed by boiling with a base and distilling.

However aldehydes will oxidize to acids much more readily than alcohols will oxidize with a strong oxidizer.

Regardless of method it is easier to just ferment sugar.

karlos³ - 5-8-2021 at 13:48

Sugar sufficient for a liter of ethanol is, here in europe, estimatedly around five times as expensive as the cheapest liter of denatured ethanol.
It might be easier, it definitely is actually, but the effort and cost involved makes denaturing denat. EtOH still much more worthwhile.

Good luck I don't need to care about these tiny IPA contaminations :o
What an effort to get rid of it!
I'm happy as soon as both MEK and denatonium benzoate are gone, especially the latter, as its much more useful to wash glass thats supposed to be used for the recrystallisation of something palpatable this way :)

Bitrex is literally the worst.
Back when I was still a smoker and washed my glass with denat. EtOH, and then smoked a cigarette a few minutes later, I was hit with all the evil bitterness that this compound bears with itself from some traces on my fingers :o
Horrible stuff!
I always feel like I can taste it again when I'm using the stuff right from the bottle as it is :D

macckone - 5-8-2021 at 17:10

Don't forget drying, hydrochloric is going to add water unless you use gas. Probably still need drying as it is going to pick up water from the air.

Keras - 5-8-2021 at 23:33

Quote: Originally posted by macckone  
Keras,
Isopropanol converts via both sn1 and sn2.
With ethanol sn2 is more favorable but the ethanol replacement is less favorable in alcohols and OH is a poor leaving group.
The thermodynamics favor isopropyl chloride over ethyl chloride but not by much.
Both will boil off as they are formed at even modest heat with ethyl chloride boiling at 12C it boils off quickly.

Thermodynamics is one thing, but kinetics are another. If the kinetics of the SN₂ is much slower than the SN₁ at the secondary carbon, then you might be able to get an appreciable amount of isopropyl alcohol out without losing much ethanol.

Thinking of it, thermodynamics won’t help you there because there’s so much more ethanol than the equilibrium hugely favours the formation of the chloroethane (IMO).

Also, what about KMnO₄. Apparently, permanganate readily oxidises secondary alcohols to ketones, but, unless prodded to, leaves primary alcohols untouched? Otherwise what says the attached paper.

Attachment: Oxidation_of_2ary_alcohols.pdf (789kB)
This file has been downloaded 40 times


macckone - 6-8-2021 at 14:07

Quote: Originally posted by Keras  

Thermodynamics is one thing, but kinetics are another. If the kinetics of the SN₂ is much slower than the SN₁ at the secondary carbon, then you might be able to get an appreciable amount of isopropyl alcohol out without losing much ethanol.

Thinking of it, thermodynamics won’t help you there because there’s so much more ethanol than the equilibrium hugely favours the formation of the chloroethane (IMO).

Also, what about KMnO₄. Apparently, permanganate readily oxidises secondary alcohols to ketones, but, unless prodded to, leaves primary alcohols untouched? Otherwise what says the attached paper.

My experience is that KMnO4 does not leave primary alcohols untouched. But it does convert them all the way to acid, which is easy to remove. The kinetics may favor the secondary over the primary.

I know in the chloride reaction the isopropyl is preferentially removed. But short of multiple distillations completely removing the isopropyl alcohol is going to still leave some residual.

Now one path is convert to everything to the respective chlorides, distill then convert back as the chlorides are much easier to separate. If you were going for ultrapure, that would probably be the method of choice.

Keras - 6-8-2021 at 23:32

Quote: Originally posted by macckone  

Now one path is convert to everything to the respective chlorides, distill then convert back as the chlorides are much easier to separate. If you were going for ultrapure, that would probably be the method of choice.


You're prolly right. But if you have one litre of ethanol to purify, this is going to be a huge task. Using a podgy nucleophile would probably solve the problem: SN on the isopropyl group would be hindered by steric occupancy, but still possible on ethanol. But we want precisely the opposite… :/

An alternative route would be to esterify with acetic acid, which is relatively inexpensive. Ethyl acetate boils at 77.1 °C whereas isopropyl acetate boils at 89 °C. They should be pretty easy to separate, provided you use a small Vigreux' column.

Keras - 7-8-2021 at 12:34

Wouldn't {urea-hydrogen peroxide} do the trick?

Tsjerk - 7-8-2021 at 12:53

If you are thinking about esterfication with acetic acid you can just as well go for the selective oxidation with chlorine/bromine. After distillation residual acetone, ethyl acetate and acetic acid would be removed by refluxing with NaOH.

[Edited on 7-8-2021 by Tsjerk]

Schleimsäure - 7-8-2021 at 15:51

Quote: Originally posted by macckone  
Don't forget drying, hydrochloric is going to add water unless you use gas. Probably still need drying as it is going to pick up water from the air.


Right, thanks, already thought about that. So maybe dried HCl, over H2SO4 in a gas washing bottle, is better. No need for ZnCl2 then too, I guess.

Otherwise depends how much HCl 37% is needed plus waterfree ZnCl2.

karlos³ - 7-8-2021 at 16:53

I am sure that oxidation at freezer temperatures, with KMnO4, would preferably pick up the IPA and oxidise this to acetone even at that temperature.
KMnO4 will be more reactive towards primary alcohols like ethanol at increasing temperature....

But, and thats just a slightly educated guess...
A tiny amount of KMnO4(maybe a few times of the amount of IPA contained in there at most) and a night in the freezer, will very likely oxidise almost all the IPA and almost none of the EtOH.

I know that KMnO4 is still a great oxidant for secondary alcohols, even at freezing temperatures.
But I also know, that primary alcohols aren't that easily and selective oxidised at such cold temperatures.

Keras - 8-8-2021 at 11:19

Apparently cyclopentane works as an entrainer to separate ethanol from a ternary ethanol/isopropanol/water mixture.

draculic acid69 - 9-8-2021 at 01:24

Quote: Originally posted by Mateo_swe  
In Sweden we call homemade ethanol made for drinking "Hembrännt", hem=home, brännt=brewed, distilled.
In my youth i had a stainless distiller rig with 20L capacity.
I made the "Mäsk" with turboyeast + common sugar in 25L pails, it took 4-5 days something to be ready for the distiller.
After distilling, diluting to 40% and purification by activated coal it tastes almost nothing, just a warmth in the chest.
Way better than store bought vodka.
The secret to very good homemade ethanol is the quality of the activated coal.
I still have the stainless distilling rig somewhere but it hasnt been used for 15-20 years.
Maybe i could start using it for making absolute ethanol.
But how to get rid of the last 5% water, molecular sieves?


Here in Oz we also call it home brew.as for the last 5% use dehydrated cuso4
or mgso4 but not calcium salts as they dissolve in etOH.

Fery - 11-9-2021 at 03:33

here I found this interesting info:
https://www.researchgate.net/post/What-is-the-most-appropria...

Quote:

Simplest classical method - reflux with CaO (BaO), distillation and susequent preparation of magnesium ethylate and reflux over them (to achive absolute alcohol).
At pressure below 70Torr, ethanol do not build azeothrope with water, so it can be distilled in relative pure form - this conditions are very attractive to room temperature pervaporation.
To avoid relative complex magnesium ethylate prep-step, absolutization can be performed by standing over 3A molecular sieves.


Has anyone tried the distillation below 70 Torr? I expect coil condenser and suitable cooling liquid necessary (for example ethylene glycol or at least very concentrated salty solution like CaCl2 or NH4NO3). Seems to be suitable experiment for winter time (to cool the cooling liquid somewhere outside during freezing winter temperatures). I expect water aspirator would be preferred as a vacuum source (through which a water with temperature above 0 C must circulate of course) because a rotary oil vacuum pump would create too low vacuum level and would require even much more colder cooling liquid.

[Edited on 11-9-2021 by Fery]

S.C. Wack - 11-9-2021 at 22:12

The question is how many theoretical plates will be required to separate such a mixture with a 16-17C difference in bp to better than 95.6% purity, and how many one's setup/hands has at 70 mm. This method is not left out of lab manuals by accident.