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Author: Subject: Purification of UK standard denatured spirits?
ChocolateStirBar
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[*] posted on 7-11-2017 at 08:51
Purification of UK standard denatured spirits?


Hi guys. As far as I'm aware the standard UK formula for "completely denatured alcohol" is:

"For every 100 parts of alcohol by volume, add 3 parts of isopropyl alcohol, 3 parts of methyl ethyl ketone and 1 gram of denatonium benzoate"

Now I read this post, which makes me believe that the MEK can be removed from this mixture:

Quote: Originally posted by karlos³  
MEK is easy to remove if you just distill the EtOH over NaOH, the MEK will self-condense in an aldol reaction to a higher boiling substance and so the EtOH can easily be freed from the MEK/its condensation product.


After distillation if I did not rush it I believe I would be left with purely ethanol and a slight amount isopropyl alcohol (likely water too). Is there any way I could remove this final isopropyl alcohol from the resulting distillate?
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unionised
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[*] posted on 7-11-2017 at 09:37


Very careful fractional distillation.
What do you want it for?
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Corrosive Joeseph
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[*] posted on 7-11-2017 at 10:19


Quote: Originally posted by ChocolateStirBar  


"For every 100 parts of alcohol by volume, add 3 parts of isopropyl alcohol, 3 parts of methyl ethyl ketone and 1 gram of denatonium benzoate"



I was always under the impression that this is the EU standard and that the UK formulation is different -

"Completely denatured alcohol must be made in accordance with the following formulation: with every 90 parts by volume of alcohol mix 9.5 parts by volume of wood naphtha or a substitute and 0.5 parts by volume of crude pyridine, and to the resulting mixture add mineral naphtha (petroleum oil) in the proportion of 3.75 litres to every 1000 litres of the mixture and synthetic organic dyestuff (methyl violet) in the proportion of 1.5 grams to every 1000 litres of the mixture."

Ref 8, taken from this page - https://en.wikipedia.org/wiki/Denatured_alcohol


/CJ
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ChocolateStirBar
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[*] posted on 7-11-2017 at 11:46


Quote: Originally posted by unionised  
Very careful fractional distillation.
What do you want it for?

Making ethyl sulfate. I do not want methyl sulfate (so ideally no methanol) and I don't even know if isopropyl sulfate exists!

I think you're also right Joseph, but a good UK source has an MSDS with the EU recipe. Having read your post more in depth I'm now pretty sure that was the old recipe for UK CDA.

[Edited on 7-11-2017 by ChocolateStirBar]
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LearnedAmateur
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[*] posted on 7-11-2017 at 12:28


Possibly a novel route, but a mixture of ethanol and isopropyl alcohol can be separated via conversion to their nitrite esters and subsequent hydrolysis. For every 10mL of spirit, 6mL of sulphuric acid and 5mL water (optional) is added and in a separate container, 13g of NaNO2 or 15g KNO2 is dissolved in 20-30mL water. After chilling the solutions to <5C, the acidic mixture is added to a flask equipped with a system for bubbling gas and an addition funnel containing the nitrite solution is placed with access to the reaction flask. Dripping in the nitrite solution at a rate of 1 drop every 2-3 seconds should create a layer of isopropyl nitrite and ethyl nitrite. When complete, allowing the mixture to come above 17C will cause the ethyl nitrite to boil - this is bubbled through a solution of sodium hydroxide, hydrolysing the ethyl nitrite to ethanol and sodium nitrite which can then be distilled and dried. Unsure on the practicality of this idea, but it might be worth a shot, I might give it a go when I get the chance to see what sort of purity I can acheive.

[Edited on 7-11-2017 by LearnedAmateur]




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[*] posted on 7-11-2017 at 12:31


Separating the nitrites is going to be a PITA. (Possibly less so than fractionating the alcohols, but...)
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[*] posted on 7-11-2017 at 13:35


I'm just thinking because the ethyl nitrite is a gas whereas isopropyl nitrite is a liquid at room temperature, then again I am familiar with the incredible volatility and vapour pressure of iPrONO having synthesised it before. Enough to pop a glass stopper out of a test tube at room temperature, so I guess there would be some isopropyl alcohol in the final product having been carried over, but it definitely wouldn't be much if the temperature is tightly controlled.



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ChocolateStirBar
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[*] posted on 7-11-2017 at 15:07


I appreciate the suggestion but as ethyl nitrite is an energetic material I do not want to work with it.
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[*] posted on 12-11-2017 at 16:12


Distilling bioethanol (from UKs well known hardware store) is the way to obtain usable EtOH (perfect for recrystallisations). After normal (not fractional) atm dist. the bitter taste was no longer present. Vapours were collected at 78 °C , only one fraction had come over.
Purple methylated spirit is full of ketones. Hard to remove from the mixture . Denatonium benzoate on the other hand can easily be removed hence its a solid compound with high vapour pressure (mp:163 to 170 °C).

[Edited on 13-11-2017 by Mush]
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[*] posted on 13-11-2017 at 00:26


To be able to purify the denatured mixtures or any other sort of "troublesome" source for EtOH one first needs a very presentable and efficient fractionation column system with full reflux regulation capability and the understanding to operate this system. The task of building or sourcing this system shall be quite complicated, long and expensive, but there really is no reasonable alternative for the task at hand....well apart from buying the pure ethanol of course, but that would be boring :)




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