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Assured Fish
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Hypothetically drinkable ethanol from methylated spirits
Today i decided to fractionally distill some methylated spirits to see how pure i could make this rather cheap and OTC source of ethanol.
I would like to make it clear that i am not an alcoholic and i am not trying to actually find a way to make denatured ethanol drinkable again, i
merely want the ethanol to be pure enough to drink so that it is sufficiently pure for just about any chemistry I desire to use it for, i do not need
help removing the water as i have molecular sieves on hand.
So the methylated spirits i have chosen to distill is Diggers violet methylated spirits:
http://www.recochem.com.au/index.php/products/consumer_produ...
This is the only msds sheet i was able to find for it and it only says it contains ethanol and water.
https://db1736767dbd5e7094bb-d61bbc5d0b342a54145a236e2d5d1eb...
The issue i am having with this stuff is that it isn't boiling at 78*C as predicted, instead its comming over at about 71-73*C.
I was curious to see if there were any bittering agents that could be messing with my distillation and so i got a drop of the distillate and put it on
my tongue, i could not detect any bitterness, it was sweet as you would expect from ethanol but with a slight caramel undertone there.
I also tried the ethanol from the bottle that it came in (using same technique), this definitely tasted weirder and more chemically but still mostly
like ethanol, a slight bitterness but definitely not with the potency of a denatonium salt.
The distillate that came over was clear thankfully which means i have atleast managed to remove the dye but i still need to know what the other
impurity might be that is lowering the BP of my ethanol.
I have done dozens of ethanol distillations in my life because i have a 30 liter pot still and a 20 liter fermentation vessel so i am generally
familiar with distilling ethanol, but currently it costs me about $10-$15 a liter to produce with the price of sugar and yeast, if i start using
methylated spirits instead, it would bring that down to about $5 a liter.
I would only drink the ethanol that i have prepared by fermentation and would never drink the stuff ive distilled this afternoon with the exception of
trying to determine impurities.
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Chemetix
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When I tried this myself once, I thought I had a really pure ethanol source for chemistry. My still has a very high plate count and a PLC module for
keeping the distilate within a range of 1-2 C. But something like a fulminate synth refused to work. Only a distillate from a ferment worked. I'd love
to run this on a GC one day. There has to be a swag of unlisted stuff in the commercial IMS.
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PirateDocBrown
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Check for methanol.
H2SO4 and Na2Cr2O7. Smell the result. If there's significant methanol, formaldehyde will overpower the smell of acetaldehyde.
Methylated spirits also sometimes have pyridine, bear in mind.
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Assured Fish
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| Quote: |
Check for methanol. H2SO4 and Na2Cr2O7. Smell the result. If there's significant methanol, formaldehyde will overpower the smell of acetaldehyde.
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Methanol does not form an azeotrope with ethanol, it normally cuts cleanly between 65*C to 78*C.
Nontheless i followed your advice because ive got a little over 100g of potassium dichromate on hand, the contents of the test tube just smelled like
rotten apples as expected from acetaldehyde.
I had another look through the azeotrope tables on wikipedia, i found only one azeotrope that kinda looks plausable, the zeotrope between water,
ethanol and acetonitrile had a BP of 72.9*C with a water conc of 1% wt, ethanol conc of 55% wt, acetonitrile conc of 44% wt.
https://en.wikipedia.org/wiki/Azeotrope_tables
Im not sure if putting acetonitrile into methylated spirits is a sane thing to be doing given the price of acetonitrile but ive decided to try and
test for the presence of nitriles.
I dont have full access to this but the following paper descibes using soda lime to thermally decompose nitriles forming ammonia which can then be
detected using a methanolic copper sulfate solution.
http://pubs.acs.org/doi/abs/10.1021/ac60140a043?journalCode=...
I have both methanol and copper sulfate on hand and can carry out a substitution of calcium hypochlorite with sodium hydroxide to precipitate calcium
hydroxide which i can then wash with water and add a pinch of NaOH and KOH, i will have to find a cork or stopper that can fit a test tube but i think
i can do this. The issue is that the ethanol might boil off before its able to react with the soda lime.
If someone has a better nitrile test id be interested to know.
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clearly_not_atara
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Diethoxymethane forms a ternary azeotrope with ethanol and water that boils around there. Maybe methanol is getting oxidized to formaldehyde and
reacting to form an acetal?
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Assured Fish
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| Quote: |
Diethoxymethane forms a ternary azeotrope with ethanol and water that boils around there
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Do you have information of the exact composition of this azeotrope, i.e. percentage of each component.
There is a test for the presence of ethers or esters called the Zeisel test which involves cleavage of the ether using HI followed by a reaction with
mercury nitrate forming mercury iodide which is a red color. It may be simpler to react with HI to form diiodomethane which could be distilled to
verify its BP and presence, this would also produce ethyl iodide. I don't have any HI but i do have HBr which might be sufficient to cleave the ether.
Option 2 if Atara could supply details regarding the composition of this azeotrope, Activated calcium chloride might be usable to remove the ethanol
and then filter off the calcium chloride and distill to determine BP.
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Corrosive Joeseph
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I have never done it but I was always under the impression that methanol and ethanol are nigh on impossible to separate totally and need many
theoretical plates.............
Here is your paper
/CJ
Attachment: trofimenko1958.pdf (436kB)
This file has been downloaded 2287 times
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Schleimsäure
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In Germany they use MEK usually to denaturate along with some ppm of denatonium benzoate. The latter should easily separate just by destillation.
To get the Ketone out the best way is to react it with Hydroxylamine for some days to form the Oxime. Afterwards destillation should result in pure
EtOH.
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byko3y
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Isopropanol is almost impossible to separate from ethanol efficiently (the cost of the separation would be higher than the cost of making ethanol from
sugar). There's not much to talk about unless you are capable of extensive analysis of your alcohol using either complex old-school
oxidation/derivatization with subsuquent weighting and titration, or an efficient GC on a calibrated device.
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Assured Fish
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Thanks for the reference CJ, as far as i am aware ethanol and methanol do not form any kind of constant boiling mixtures, you might be right about
separating every last trace of methanol from ethanol but for most application this really isn't necessary. A lot of home brewers including myself
don't use a particularly long fractionalation column (mines 100mm) and they are generally able to separate the methanol after the first distillation,
though normally 2-3 distillations are required with a column this small but this is mostly to remove the higher boiling alcohols referred to as fussel
alcohols.
I could be wrong though but i haven't found any references to suggest otherwise.
| Quote: |
In Germany they use MEK usually to denaturate along with some ppm of denatonium benzoate. The latter should easily separate just by destillation. To
get the Ketone out the best way is to react it with Hydroxylamine for some days to form the Oxime. Afterwards destillation should result in pure EtOH.
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This particular mixture that i have been messing with has a BP of about 72*C, MEK and ethanol azeotrope has a BP of 74.8*C, this is certainly worth
considering because im very close to the sea and its possible the air pressure here could be higher than normal, or my thermometer is out.
| Quote: |
Isopropanol is almost impossible to separate from ethanol efficiently
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I haven't found any data in regards to isopropanol and ethanol mixtures could you provide a reference.
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byko3y
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Assured Fish, you should start with basic theory of distillation, which you don't seem to be familiar with. Separation of two liquids
with 4.3°C b.p. difference using distillation is an extremely energy consuming process requiring appropriate devices for extensive processing.
For example, "A Small Scale Approach to Organic Laboratory Techniques" - Donald L. Pavia, p. 729-748, Technique 15. Fractional Distillation,
Azeotropes.
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Assured Fish
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| Quote: |
Assured Fish, you should start with basic theory of distillation, which you don't seem to be familiar with
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How has what ive said in this thread conveyed that i do not know the basic theory of distillation?
I appreciate the book as its not one ive ever read and that section on fractional distillation definitely had some interesting info specifically on
Raoult's law but to merely call my knowledge insufficiant to be carrying out such a process and just give me a book to read without pointing out my
actual faults in the theory is rather inconsiderate.
| Quote: |
Separation of two liquids with 4.3°C b.p. difference using distillation is an extremely energy consuming process requiring appropriate devices for
extensive processing.
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I am not attempting to separate two liquids with a BP difference of 4.3*C, Part of this discussion has been towards the fractional distillation of
ethanol. I am very familiar with the amount of energy required during fractional distillation as i have spent the past 3 day and over 20 hours just
fractionally distilling 800mls of ethanol from some methylated spirits (pointless perhaps but im doing so nonetheless).
This particular brand of methylated spirits does not appear to have any methanol in it, i can make this assumption because the msds did not say it
contained methanol and also i have distilled more than my fair share of methylated ethanol in the past and I always collect a cut at the 65*C mark
which is the BP of methanol, If there is methanol present it is likely formed a ternary azeotrope with a third component.
When i was referring to distilling large quantities of ethanol from a fermentation batch I used a large steel pot still that has a 100mm collumn that
i pack with marbles, this still is specifically geared towards home brewers. When i referred to distilling ethanol from the methylated spirits I was
using a 1000ml erlenmeyer flask connected to a 200ml vigreux column connected to a still head and thermometer and a 200ml liebig condenser, The bottom
of the flask was heated using heating tape and stirred with a magnetic stirrer, the entire column and flask were insulated using aluminium foil in
order to get the vapor up to the head because its rather cold here. The drip rate throughout the entire distillation was about 20 drips per minute and
this remained consistent.
The issue i am having is that i did not get a clean cut of ethanol boiling at 78*C, instead I collected a distillate at about 72-73*C, this distillate
both smelt and tasted like ethanol, i do not know what the other components are that have driven down the BP of my distillate but I suspect that it
was an azeotrope because it had a consistent BP throughout the distillation and my vigreux column would have been sufficient to exclude most other non
azeotropic components.
byko3y If you have discrepancies with my process or reasoning please specify.
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byko3y
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I can tell you what denaturated ethanol in my region contains: it's gasoline, isopropanol, ethyl acetate, and denatonium benzoate.
Distillation columns you use are insufficient to satisfy standards for food alcohol even after two distillations. There could be no excuse for alcohol
to boil at 72-73*C - it clearly contains some major contaminations, such as esters and acetaldehyde.
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Assured Fish
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byko3y you seem to have taken the title of this thread a little to seriously, I know for a fact that i will not be able to purify the
ethanol from denatured alcohol pure enough to be considered safe for regular consumption, thats why i named the thread "Hypothetically
drinkable ethanol".
My intention (which you would understand if you had read my original post on this thread) is to make sufficiently pure ethanol from denatured alcohol
so that i could use it for just about any reaction involving ethanol that i can think of e.g. preparing sodium ethoxide, haloethane, nitroethane etc.
Alcohol boiling at 72-73*C is not an excuse its a problem, one that i intend to solve and hence the reason for this thread. I intend to identify this
contaminant and then if possible remove it.
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Corrosive Joeseph
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The ethanol-ethyl acetate azeotrope boils at 71.8c and is 69.2% by weight with a specific gravity of 0.863
/CJ
[EDIT] - Source - https://en.wikipedia.org/wiki/Azeotrope_tables
[Edited on 5-6-2017 by Corrosive Joeseph]
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byko3y
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Hypothetically you can drink a pure isopropanol. If you need ethanol for reaction, then you should try refluxing it with NaOH and then distilling.
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Assured Fish
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Thank you again CJ I had overlooked that azeotrope but more importantly i had forgotten to check the density.
43.685g / 55mls = 0.794273
So it doesn't look like its ethyl acetate unfortunately. Keep in mind though this stuff may contain water (although water would likely increase its
density), haven't added any water but its likely some has been absorbed by the atmosphere.
Tomorrow i will dry some molecular sieves and try to dry the ethanol to get a more accurate specific gravity.
byko3y I considered doing just that but only if i was able to detect a denatonium salt, the idea was that the NaOH would somewhat decompose the
denatonium salt enough for it to not make it through distillation, alas I couldn't taste any bittering agents in either the bottled stuff or the
distilled stuff.
Edit: As a side not i just checked the specific gravity for the ethanol acetonitrile azeotrope on this table and it says its 0.788,
it does not have the specific gravity for the water/ethanol/acetonitrile ternary azeotrope but as i stated earlier, its likely the presence of water
will increase its specific gravity somewhat.
[Edited on 6-6-2017 by Assured Fish]
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clearly_not_atara
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Practical considerations regarding the diethoxymethane/ethanol/water system are disclosed in this patent:
https://www.google.com/patents/US4740273
although the nature of the ternary azeotrope is referenced to this patent with an older separation method:
https://www.google.com/patents/US4613411
| Quote: | | A quantity of ethanol/diethoxymethane distillate (541 ml.) removed from the first column is added to a second flask with an identical distillation
column. This solution contains 248 ml. of diethoxymethane, 255 ml. of ethanol and 38 ml. of water. To this solution is added 450 ml. of cylclohexane
in order to form an azeotrope with ethanol (63% cyclohexane, 37% ethanol). |
We can assume this (47EtOH:46(EtO)2Et:7H2O) is reasonably close to the azeotropic composition. However based on this I think it is unlikely that DEM
is your problem because the ethanol/DEM azeotrope contains a large amount of DEM.
[Edited on 6-6-2017 by clearly_not_atara]
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alking
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Ime it's best to start with a relatively pure source of ethanol and even then it's hard to concentrate it to 95%, and especially so to remove any
lower boiling components. With a well insulated 500mm steel wool packed column and a large still head (consisting of a half packed 250ml
chromatography reservoir connected to a claisen adapter (plus thermometer) and then a 105 degree adapter) it takes me about 24hours to concentrate
1.75ml to ~92-94% EtOH.
From there I will dry it with molecular sieves and redistill if I need it to be more concentrated, however then it boils at around 74.5C so clearly
there are some lower boiling components present and that is from drinkable ethanol. I'm not sure what they are, but I imagine they form an azeotrope
as I cannot get a stable distillate to come over less than that, probably some combination of ketones, aldehydes, and ethyl acetate I would imagine.
To get rid of ketones and ethyl acetate you could reflux the EtOH in a strong base. The ketones will polymerize and the ethyl acetate will hydrolyze
to acetic acid and ethanol, the acetic acid will then further react to form a salt with your base. I do not believe the aldehydes will react, but you
can form a complex with a sulfite salt as well. All of that is a lot of work just to get pure ethanol though.
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Assured Fish
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@alking By pure drinkable ethanol do you mean vodka?
If you ferment your own the only component that has a lower boiling point than ethanol is methanol.
I tried the nitrile test today, I added 3mls of the ethanol to a test tube with a bit of calcium hydroxide at the bottom, I sealed the test tube and
connected a bent glass tube to the seal test tube and ran the other end into a methanolic copper sulfate solution. I heated the test tube containing
the ethanol using a blow torch and watched as the ethanol boiled out an into the methanol solution.
No cloudiness was seen and no other reaction appeared to be happening.
To test the activity of the methanolic copper sulfate solution I added some aqueous ammonia to it and it immediately produced a purple precipitate.
Conclusion: It would appear as if the test was negatve for the presence of acetonitrile.
The only thing is that i had used calcium hydroxide that i had prepared myself, thus im not sure if it was actually capable of decomposing the nitrile
to ammonia before the acetonitrile/ethanol distilled out of the test tube.
I think im going to try what everybody else is suggesting and reflux with some NaOH followed by distillation. The other idea i had was to try and
remove the ethanol using a copious amount of calcium chloride and then distilling it to see what the other components are.
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Corrosive Joeseph
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Oh dear, you are in for a big shock............!!
Ethanol is the main product of fermentation but depending on many things there could also be methanol, longer chain alcohols, aldehydes, ketones,
organic acids, esters, lipids, sulphur compounds, amino acids and who knows what else
Check this out -
https://byo.com/body/item/630-fermentation--flavor-compounds...
And.......... Taken from another page
"Where does the methanol come from?
Basically it can be produced biologically in 2 ways; through the oxidation of methane by methane monooxygenase, or by the reduction of formaldehyde,
by methanol dehydrogenase (and this reaction normally works in the reverse direction).
It's true that some methanol can be produced during fermentation, but this is not derived from the ethanol or by carbohydrate oxidation. It is
produced in small amounts, either by non-enzymatic reactions or through the reduction of formaldehyde."
Methane isn't present in our washes, so the culprit is formaldehyde. I believe the pectins in fruit are methylated and can break down in the wash into
formaldehyde. But so long as your wash has only pure fermentable carbohydrates, you can expect essentially zero methanol.
Ethyl acetate, OTOH, is produced spontaneously whenever acetate is present with ethanol. There are several possible sources of acetate during
fermentation. In general, acetate is formed by oxidation of ethanol. (In fact, acetate is the 'end-product' of our own metabolism of ethanol). In
fermentation, oxidation of ethanol into acetate can happen as a result of desperate yeast metabolizing its own ethanol, or by contamination with other
yeasts or bacteria.
Methanol is formed when fermenting beverages high in pectins - eg grapes and berries. Starting with a grain or sugar based wort, in a clean fermentor
with a yeast culture from a well aereated source will result in small/none formed.
The methanol comes from the pectin, which mainly composed of methyl esters of galactose. When pectin breaks down, by enzymes introduced by
microorganisms, or deliberately introduced, the methyl esters combine with water to produce methanol, so the aim should be to leave the pectin well
alone if you can.
Fermenting at a high temperature, or adding pectin enzyme, or trying for an abv higher than 12% all increase the risk of methanol being produced, so
low temperature fermentation, adding no exra enzymes, and a target lower than 12%abv is all good stuff.
What causes excessive methanol production during fermentation?
It isn't the yeast that controls methanol, it's what you're fermenting. I believe yeast has very limited metabolic pathways around methanol.
Why is methanol bad and does it really make you go blind?
Methanol is an especially nasty type of alcohol because the body tries to break it down the same way it metabolizes, or breaks down, ethanol, the type
of alcohol in beer, wine and other drinks. Metabolizing ethanol produces chemicals less toxic to the body than alcohol. Unfortunately, if the same
chemical action is performed on methanol the result is formic acid, lactic acid and formaldehyde.
Formaldehyde attacks nerve cells, especially the optic nerve and can damage the liver and kidneys. Formic acid and lactic acid also attack the kidneys
and liver. Most people who have drunk methanol die of severe and sudden kidney and liver failure.
How do we get rid of or prevent the formation of methanol?
A simple (but effective) rule of thumb for this is to throw away the first 50 mL you collect (per 20 L mash used) for a reflux still. If using a
potstill, make it more like 100-200 mL. Do this, and you have removed all the hazardous foreshots, including the methanol. To get a really clean
distinction between the foreshots and the rest of the alcohol, increase the reflux ratio to the point where you're taking off this first 50 mL at a
very slow rate (eg 1 drop per second). This will give a very stable equilibrium within the column to allow all the methanol to collect at the top of
the column and be in this first portion.
If you are doing a double or triple distillation with a pot still, don't worry about removing the heads & tails on the first pass. Wait for the
second run, when they are more distinct & easier to seperate. Once you have removed them, they are gone, so much less will need to be discarded
from the subsequent runs, other than that dictated by taste, and any improved seperation that may result from running a more pure distillate through
the still.
In order to prevent a high methanol content (I'm sure distilling the pectin turns it into methanol), distillers must fully clarify any fruit wine
before cooking it. Rather than use clarifiers, put the wine into 2 or 4 liter plastic jugs (only filled half full) and freeze them solid, then thaw
them out, this will result in perfectly clear (and chill- stabilized) wine ready for distilling. After the thawing is complete or maybe as much as a
week after, the wine will be crystal clear.
pretty interesting. i think that answers about all the questions we had on the methanol production during the fermentation process....."
Hope this helps.
/CJ
[Edited on 9-6-2017 by Corrosive Joeseph]
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Assured Fish
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Im not at all shocked CJ, i did after all state "the only component with a BP LOWER than ethanol was methanol"
And yes i do also follow the cutting rule and cut the first 50-100mls, I wouldn't cut the first 200mls though that sounds a little insane.
I am also quite careful about getting any higher boiling components in my final product, usually they leave a slight banana smell in the ethanol.
I normally run the first distillation by cutting the first 50mls there and then trying to again predict and cut the last 100mls.
then for the second distillation i again cut 50mls at the beginning and then again try to predict and cut the last 50mls.
For the third and final distillation i don't cut the first run at all and just focus on cutting the last 50mls.
I normally get about 1.5 liters of about 92% ethanol per 20 liter ferment. I use a turbo yeast which can handle ethanol concentrations up to 20%.
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Corrosive Joeseph
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Many of those compounds have a lower BP than EtOH, but there shouldn't be more than trace amounts
Anyways, I thought you might like that, sorry for dragging the topic slightly adrift.........
A friend of mine does quite a lot of brewing and distilling, I have seen my fair share of it.
The initial heads are quite visible and 'bitty', and checking with a shot glass (his set-up is quite primitive), he just cuts when the distillate is
clear. Same on the other end, with a little bit of practice, the operator will know when to expect the 'oils'.........
We are in the process of building him a larger pot with fractionating column and thermometer. I will report sometime in the near future.
Your yield doesn't sound so good........... If I do the math, my buddy gets 3.4 litres of 100% per 20 litre ferment.
That's only first distillation though, with all heads and tails removed.
But that is all the alcohol he is going to get from that batch.
The theoretical yield from his 23% Turbo Yeast is 4.6 litres per 20 litre brew, but I have never seen this
I am going to experiment with our own brand of denatured here soon but it has a different composition to your own.
Hope I have been of some help.
Regards
/CJ
[Edited on 9-6-2017 by Corrosive Joeseph]
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alking
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Quote: Originally posted by Assured Fish  | @alking By pure drinkable ethanol do you mean vodka?
If you ferment your own the only component that has a lower boiling point than ethanol is methanol. |
Yes, I mean vodka. There's definitely aldehydes, ketones, and acetic acid/ethyl acetate present as well though. I have no idea how much, likely quite
minor, but they're production is unavoidable in the fermentation process.
I suspect cheap spirits are going to have a higher concentration of them due to how it's made industrially. They likely concentrate the drinkable head
and tail fractions into the cheaper alcohols while the middle goes to the best. If they do multiple distillations perhaps the top and bottom are again
recombined in the cheaper variants to further concentrate the lower boiling components resulting in much more than you would normally have from
homemade alcohol or an otherwise standard fractionation with a simple head and tail removal. Just guessing, I don't know.
I also don't know for sure how accurate my 74C distillation temp is because I do know my thermometer is off to some degree, but I've used multiple
thermometers and I have no doubt it's significantly below 78.1C as they all register within a degree. You can also smell the contaminants, pure EtOH
doesn't have much smell, but aldehydes, ketones, and ethyl acetate are pretty pungent.
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AJKOER
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I read that methanol is much more vigorous in reacting with a Mg alloy (or Mg with a catalyst including chlorides of Hg, Cd, Pd, Co, Ni,..., which
could than form a galvanic couple, see G.H. Lee, et al, "Magnesium in Methanol (Mg/MeOH) in Organic Syntheses", published in Current Organic
Chemistry, 2004, 8, 1263-1287 1263, full text available at https://www.google.com/url?sa=t&source=web&rct=j&... , which is an SM talk file ) than ethanol.
You may be able to use this to quickly visually (as distinct from smell based methods) estimate CH3OH content by running comparative tests with a pure
methanol and a pure ethanol sample for your particular magnesium alloy source.
The reaction between Mg and methanol is said, after a possible inception period, to procedure in an exothermic manner that may require cooling.
As a source reference in the possible use of magnesium, as Mg turnings pretreated with HCl and employed at 50 C in some organic synthesis, please see
commentary at: http://pubs.acs.org/doi/abs/10.1021/jo00210a035 . Article: "Magnesium in methanol: substitute for sodium amalgam in desulfonylation reactions", by
Alan C. Brown and Louis A. Carpino, in The Journal of Organic Chemistry, Vol. 50: Issue. 10: pages. 1749-1750, 1985.
[Edited on 10-6-2017 by AJKOER]
[Edited on 10-6-2017 by AJKOER]
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