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Author: Subject: Purification of denatured alcohol
kclo4
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[*] posted on 16-6-2005 at 15:34
Purification of denatured alcohol


Denatured alcohol contains methanol and ethanol it is obviously hard to separate and I am not to sure if it is even possible but if you turned it in to NaOCH3 and NaOCH2CH3 it seems like there could be a way having both the salts with different melting points dose a any one have an idea how to separate the two

Melting point of NaOCH2CH3 = 260 C
I cant seems to find the other ones meting point




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12AX7
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[*] posted on 16-6-2005 at 15:48


Then instead of an azotrope you have an eutectic. If they form either, that is.

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Marvin
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[*] posted on 17-6-2005 at 01:59


Methanol and Ethanol do not form an azeotrope but the composition of the vapour is close to the composition of the liquid so a very good reflux column is needed for any seperation.

The question is really, not how do I seperate, but how well can I seperate. What ever you do there will be some methanol in your ethanol and vice versa. I would suggest it isnt practical to make drinkable ethanol this way. If you need the methanol reduced for general chemistry this is probably feasable.

The only relavent data I was able to find is here,

http://users.chartertn.net/lpartin/software.html
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Hellhound
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[*] posted on 19-6-2005 at 11:13


Pirydine and its bases are also often added to EtOH to make it undrinkable.
They gave alcohol bitter taste and cold be revealed with litmus paper. Pirydine boiling point is 115 'C and it can't be removed from alcohol either by distilling or freezing. Maybe an addition of some mineral acid would cause it to turn to pirydinium salts(though i don't know about solubility of these salts).
On the other hand ,pirydine can easily coordinate with any metal ions(e.g. Ag , Al , Co & Cu chlorides) giving insoluble complexes.
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The_Davster
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[*] posted on 19-6-2005 at 11:34


I have some 95% EtOH that is denatured with camphor, diethyl benzy benzoate and diethyl phthalate. It is a brand of rubbing alcohol.



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FriendlyFinger
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[*] posted on 19-6-2005 at 16:01


The Denatured alcohol I use has 95% ETOH, 4.25% H2O 0.25%; MIBK, Denatonium Benzoate and Fluoroscein.

I'm told you remove the MIBK using NaOH and distilling. How exactly do you do that, and what about the rest of the junk?

Thanks,
regards FF
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Hellhound
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[*] posted on 19-6-2005 at 17:12


MIBK can react with oxidizing agents, you may try to treat your alcohol with KMnO4 and then decantate cleared liquid. (Through this reaction various carbon acids may appear and probably you have to neutralize them). In some cases i think this method would be more convenient.
Fluoresceine,as it's triphenylmetane dye, can be also easily oxidized,though intermediate products, such as quinones may appear.
Camphor oxidizes easily with KMnO4 or other reactants to CO ,CO2 and H2O.
I don't know about denatonium benzoate. Judging by formula ,it's not so easy to oxidize this.
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sparkgap
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[*] posted on 20-6-2005 at 02:59


"...I don't know about denatonium benzoate. Judging by formula, it's not so easy to oxidize this."

I guess not. :) But maybe an alkaline extraction might be useful? It's still a quaternary ammonium compound after all.

(edit: heh, missed that, cyclonite4's right, it'll all become acetic acid if you keep ethanol and permanganate standing long enough.)

sparky (~_~)

[Edited on 20-6-2005 by sparkgap]




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cyclonite4
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[*] posted on 20-6-2005 at 03:41


Quote:
Originally posted by Hellhound
... try to treat your alcohol with KMnO4 ...


Somehow I see this oxidising the ethanol too (to ethanal and ethanoic acid)!




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Hellhound
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[*] posted on 20-6-2005 at 04:32


I agree about oxidizing EtOH too, but ,believe it or not, there's a long history of cleaning alcohol with KMnO4.
The hint is that a lot of admixtures will oxidize more quickly before a decent amount of EtOH would. (e.g. camphor, etc...)
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[*] posted on 20-6-2005 at 14:38


So what's the proceedure for removing MIBK? Do you just ad a bit of NaOH and distill? Simple as that?
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hAzzBEEn
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[*] posted on 22-7-2005 at 07:24
Methanol removal... moonshiners


I've read in distillation (moonshine) literature that methanol is removed from "mash" (mixture containing ethanol) by distillation and discarded. They are usually talking about < 1% methanol, but sometimes close to 1%, depending on the starting material for the fermentaion. They usually monitor/control the temperature in the boiling pot, and control the temperature in their uper and lower column by controlling the flow of cooling water to each.

With ethanol boiling at 78.5 F or ethanol/water azeotrope at 78.15 F and methanol (no azeotrope with water) boiling at 64.7 F, this seems feasible. One source did this by starting the boiling pot at 70 F and upper column at 62 F (for theirs). They carefully slow the flow of cooling water to the column until the temp at column top rises to 68 F and this releases the methanol vapor to the condensor. This is held until no more distillate is produced.

Could one use a vertical condensor with some type of packing as a column for temp control and a distilling adapter with thermometer on top of that to monitor the temperature? One could place a T in the cooling water line - run one of the outlets to the reflux condensor (column) and one to a shutoff valve and a return line to the cooling water tank or drain. The valve could be opened to slow the cooling water to the column and control the temperature. I have a T for my water hose with a valve for each outlet that could suffice (hard to control). If one column condensor wouldn't produce the temperature difference needed, maybe two would be required.

I know this is much more trouble than it's worth; this is pure curiosity. If I wanted ethanol, I'd just buy some Everclear or other PGA. It may be easier to control the temperature in 4 ft tall columns used for distilling 'shine. I'm sure the temp in the copper or stainless columns responds faster to the cooling water. It seems like if a moonshiner could do it, a mad scientist could do it, better. Enlighten me.


[Edited on 22-7-2005 by hAzzBEEn]




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neutrino
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[*] posted on 22-7-2005 at 07:30


Yes, a simple fractional distillation should do. A trick used by those too lazy to go to all this trouble is to just discard the first part of the distillate. By the law of partial pressures, most of the methanol is there.
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hAzzBEEn
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[*] posted on 22-7-2005 at 07:50


Yes, I have also read about this shortcut. I think the shortcut is used by most home distillers. I was quite interested in this some time ago.

According to the FDA:
Quote:
The Food and Drug Administration (FDA) advised ATF that 0.1 percent of methanol by volume in wine was a safe level. Any wine containing methanol in excess of this amount is deemed adulterated pursuant to the Federal Food, Drug and Cosmetic Act, 21 U.S.C. 34l(a)(2)(C) and 348

I found that info in the Methanol Info located at homedistiller.org. I thought it was ironic that on the same page, this was found:
Quote:
Methanol is a by-product of fermentation; more methanol is produced in fruit fermentation than in grains. Brewers do not remove the methanol in beer and wine because methanol is not especially toxic at low concentrations. You are looking at between 0.4%-1% methanol in wines and brandies and smaller amounts in beers. Distillers remove almost all the methanol in most cases. Ever notice how vodka produces clean hangovers and wines (particularly reds) give you very nasty hangovers? Methanol. That, and dehydration!




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[*] posted on 2-8-2005 at 21:20


Interesting quote hazzbeen.

As Neutrino mentioned, most home distillers just toss the first couple ounces that come over.

I don't know if it's such a good idea to use a fractionalizing column with storebought denatured alcohol until it's been 'cleaned' up so to speak. The actual column is expensive, and rather large, mine is about 1.4m in height and has electric heating elements and probably the biggest thermometer I've ever seen.
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[*] posted on 10-5-2016 at 17:53


Perhaps use borate esters to separate them? Trimethyl borate boils at ~68C and triethyl borate boils at >100C. Both are decomposed into the alcohol + boric acid in water



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[*] posted on 11-5-2016 at 05:47


Around here the denat. alcohol contains whopping 1% of denatonium benzoate(or so the safety data sheet claims) and about 2% of methyl ethyl ketone.
But what is weird that the website says its denaturated by adding 2 grams of denatonium benzoate to 100 liters of ethanol, but that was years ago when i saw it....
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[*] posted on 11-5-2016 at 05:56


Denatonium benzoate tastes foul, doesn't it? Is denatured alcohol just horrible-tasting or actually toxic?
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[*] posted on 11-5-2016 at 06:03


If you need pure you make it your self! but as a challenge re-distilling denatured would certainly fun.

Very care full temp control, slow raising of heat. Then perhaps some different adsorbents to help remove impurities.
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[*] posted on 11-5-2016 at 09:53


Quote: Originally posted by Eosin Y  
Denatonium benzoate tastes foul, doesn't it? Is denatured alcohol just horrible-tasting or actually toxic?


If there's methanol added, it's toxic.




As below, so above.
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mr.crow
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[*] posted on 14-5-2016 at 19:52


Quote: Originally posted by The_Davster  
I have some 95% EtOH that is denatured with camphor, diethyl benzy benzoate and diethyl phthalate. It is a brand of rubbing alcohol.


This is the "Rubbing Alcohol Compound" in the drug stores here.

(even though the post I'm replying to is old it is still relevant to the thread)

I poured 1.5 liters of this rubbing alcohol compound into a gallon jug and mixed in ~20g of NaOH. After a month of sitting around it turned brown from the camphor. The aldol reaction will get rid of ketones. Diethyl phthalate will hydrolyze to sodium phthalate and ethanol. Denatonium benzoate will be neutralized to denatonium hydroxide and sodium benzoate with possible degradation of the quaternary ammonium.

WARNING!!! The NaOH will etch your distilling flask. Neutralize it first by adding some sodium bicarbonate or bisulfate.

This is for solvent use. Don't drink it! If you are a hopeless alcoholic then make some prison wine by mixing sugar and baking yeast.

Denatonium benzoate synthesis https://www.youtube.com/watch?v=GOw_I42eUpM
Tasting denatured alcohol https://www.youtube.com/watch?v=ep2I3Gf3Sec




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[*] posted on 17-5-2016 at 14:14


What kind of equipment would be required for removing methyl ethyl ketone and denatonium benzoate from ethanol? The €8/liter price for 99,8% purity is quite tempting.
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[*] posted on 18-5-2016 at 08:42


Here is a new and possibly 'radical' path, that some may find an interesting experiment.

Start by infusing a mixture of C2H5OH, CH3OH and H2O with N2O. Apply sunlight possibly in an atmosphere of O2 and mild heating to foster a largely gas phase photolysis with occasional shaking (or ultrasound). Then distill to recover the targeted ethanol.

Logic: The action of sunlight on N2O and water forms the hydroxyl radical, *OH and liberates nitrogen from the solution.

N2O + H2O + hv → N2 + *OH + OH-

The action of the *OH on the alcohols forms *CH2OH and *CH3CHOH (and H2O) via a H-atom abstraction taking place primarily at the methyl site of methanol and at the methylene site for ethanol. See, for example, full text available at: https://www.researchgate.net/publication/222191508_Kinetics_... and also: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4190665/

*OH + CH3OH → H2O + *CH2OH

*OH + C2H5OH → H2O + *CH3CHOH

The quantity of N2O (and formed therefrom hydroxyl radicals) employed should be sufficient to remove all methanol plus more. The reaction is based on the possible preference for methanol conversion in the gas phase over ethanol (a weak kinetic argument favoring the presence of the lighter CH3OH in the vapor state given the application of heat and sunlight).

Also, I suspect further reaction of the formed radicals with oxygen, producing products with heavier molecular weights and lighter, for example per equation R14 in the second reference:

O2 + *CH2OH → H2O + CH2O

Per Wikipedia (https://en.m.wikipedia.org/wiki/Formaldehyde ), Formaldehyde does not accumulate in the environment as it is broken down within a few hours by sunlight (or by bacteria):

CH2O + hv → Products

Other paths:

*OH + CH2O → H2O + *HCO (see https://www.google.com/url?sa=t&source=web&rct=j&url=http://...

*HCO + *OH → H2O + CO

Hopefully, ethanol can be more easily recovered in post distillations discarding the 'head' and 'tail'.

[Edit] I do not recommend this as a path to potable ethanol given health issues with many of the intermediate compounds, nor do I recommend consuming N2O infused booze during sunbathing.

[Edited on 18-5-2016 by AJKOER]
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