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.
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.Chemetix - 3-6-2017 at 00:59
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.PirateDocBrown - 3-6-2017 at 04:29
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.Assured Fish - 3-6-2017 at 17:22
Quote:
Check for methanol. H2SO4 and Na2Cr2O7. Smell the result. If there's significant methanol, formaldehyde will overpower the smell of acetaldehyde.
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.
clearly_not_atara - 3-6-2017 at 18:09
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?Assured Fish - 3-6-2017 at 19:31
Quote:
Diethoxymethane forms a ternary azeotrope with ethanol and water that boils around there
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.Corrosive Joeseph - 4-6-2017 at 03:52
Methanol does not form an azeotrope with ethanol, it normally cuts cleanly between 65*C to 78*C.
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 2057 times
Schleimsäure - 4-6-2017 at 13:51
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.byko3y - 4-6-2017 at 14:41
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.Assured Fish - 4-6-2017 at 15:40
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.
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
I haven't found any data in regards to isopropanol and ethanol mixtures could you provide a reference.byko3y - 4-6-2017 at 15:59
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.Assured Fish - 4-6-2017 at 19:17
Quote:
Assured Fish, you should start with basic theory of distillation, which you don't seem to be familiar with
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.
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.byko3y - 5-6-2017 at 01:28
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.Assured Fish - 5-6-2017 at 02:11
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.Corrosive Joeseph - 5-6-2017 at 02:21
The ethanol-ethyl acetate azeotrope boils at 71.8c and is 69.2% by weight with a specific gravity of 0.863
[Edited on 5-6-2017 by Corrosive Joeseph]byko3y - 5-6-2017 at 02:32
Hypothetically you can drink a pure isopropanol. If you need ethanol for reaction, then you should try refluxing it with NaOH and then distilling.Assured Fish - 5-6-2017 at 20:35
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]clearly_not_atara - 6-6-2017 at 15:22
Practical considerations regarding the diethoxymethane/ethanol/water system are disclosed in this patent:
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]alking - 8-6-2017 at 08:34
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.Assured Fish - 8-6-2017 at 21:45
@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.Corrosive Joeseph - 8-6-2017 at 22:42
If you ferment your own the only component that has a lower boiling point than ethanol is methanol.
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
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]Assured Fish - 9-6-2017 at 02:29
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%.Corrosive Joeseph - 9-6-2017 at 02:55
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]alking - 9-6-2017 at 14:26
@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.AJKOER - 10-6-2017 at 12:43
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]AJKOER - 10-6-2017 at 16:31
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 proceed in an exothermic manner that may require cooling. One of
the products of the reaction is Mg(CH3O)2.
Example of some possible reaction paths with a galvanic couple producing a current:
2 CH3OH + 2 e- = 2 CH3O- + H2
Or, a path leading to HCHO:
H2O + e- = .H + OH-
CH3OH + .H = .CH2OH + H2
.CH2OH + Fe(lll)/Co(lll) = HCHO + H+ + Fe(ll)/Co(ll)
Reference: See equations (1), (3) and (4) in the open article, "Dehydrogenation of anhydrous methanol at room temperature by o-aminophenol-based
photocatalysts", by Masanori Wakizaka, et al, in Nature Communications 7, Article number: 12333, (2016), doi:10.1038/ncomms12333:fc "Dehydrogenation
of anhydrous methanol at room temperature by o-aminophenol-based photocatalysts", by Masanori Wakizaka, et al, in Nature Communications 7, Article
number: 12333, (2016), doi:10.1038/ncomms12333, Link: http://www.nature.com/articles/ncomms12333
Another reference, in the possible use of magnesium metal, cites Mg turnings, pretreated with HCl and employed at 50 C, in select 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 11-6-2017 by AJKOER]
[Edited on 11-6-2017 by AJKOER]draculic acid69 - 23-4-2019 at 18:39
I was about to start a post about this exact thing and as I googled the page I was looking for this post popped
up.https://forums.whirlpool.net.au/archive/2235624 is the best discussion on this topic so far.i would try a sodium bisulfite addition to trap ketones
and aldehydes.or a boil with hydroxides to break any esters and polymerize ketones and aldehydes. I'd also recommend a cryogenic crystallization to
freeze out any unwanted substances.in the above link the guy describes an olive oil purification that sounds like a really clever trick.Boffis - 10-5-2019 at 10:18
We use a clear "bio-ethanol" in table warmers. It has a distinct small of MEK so today I tried a little experiment and add a few ml of 50% sodium
hydrogen sulphite solution to it. The alcohol became cloudy but that could be jst the low solubility of Na H sulphite in 95% alcohol. The label on the
can does not state what the denaturants are but distillation alone did not remove the smell of MEK. Interestingly the bisulphite solution did! I
filtered off the white precipitate, the quantity was tiny and is drying at present but when mixed with a little dilute acid it regenerates the ketone
smell plus sulphur dioxide.
The filtered alcohol was treated with calcium hydroxide to precipitate the excess SO2 as calcium sulphite. Tomorrow I'll filter and distill it.Pumukli - 12-5-2019 at 11:25
Great! Please keep us updated on how well/unwell the process really went! I've been working with MEK denatured ethanol recently and reached a point
where this denaturant really caused problems. (No, it was not about strengthening apple cider.)zed - 14-5-2019 at 18:22
Hnuh?
Converting methylated spirits to drinking likker?
Gosh! Sounds like a great idea.
Keep us posted!
But, buy yerself a braille-keyboard, or a voice activated computer system, and practice with it for a while, before you embark on the ultimate
drinkin' experiment.
That way, if things go squinky, you can still share your results with us.Pumukli - 15-5-2019 at 01:51
In these parts of the globe "methylated spirits" is a misnomer, the actual product doesn't contain methanol. It is pure ethanol but made undrinkable
by addition of methyl-ethyl-ketone and/or denatonium benzoate, sometimes a dye also added.
So if one could get rid of the denaturant ketone the resulting ethanol would -in theory- become drinkable.
Getting rid of the ketone is the tricky part of course, because it forms an azeotrope with the ethanol and can't be separated easily. draculic acid69 - 15-5-2019 at 07:20
Here in Australia the metho as it's known contains no methanol either. I think it's denatonium benzoate mek, ethyl acetate and some other stuff
suspected to be cyclohexyl something or other. I think the purple stuff has a different composition to it as it smells different.but I think they can
definitely be made drinkable.zed - 16-5-2019 at 15:30
Ah! Well, here in the USA, "Methylated" means "Methylated".
Often 20% Methanol, or higher. I recently considered purchasing some Methylated Spirits for lab use. Had so much Methanol and other weird shit in
it, that I decided it just wouldn't work out. The Methanol to Ethanol ratio, was very unfavorable.
This stuff will blind you and kill you. Might have enough Methanol present, to kill you, three times over.
Moreover, the ATF (Alcohol, Tobacco, and Firearms) is wildly enthusiastic about imprisoning folks who produce distilled ethanol products, without
paying the beverage tax.Assured Fish - 16-5-2019 at 21:45
Zed The reason i started this thread was not to make a cheap source for ethanol for drinking purposes, the thread title might be a
tad misleading (i had assumed people would understand the hypothetical part).
Im pretty sure we all have access to methylated spirits OTC for cheap and so i just wanted to find a way to make this stuff pure enough to use for any
chemical reaction no matter how scrupulous the required conditions.
I know a few people have tried using methylated spirits ethanol in certain preps and found it to fail whereas ethanol prepared from fermentation tends
to work fine.
The issue is that we cannot all do our own ferment and sugar isn't cheap.
I think i have come to the conclusion that in reality if i needed ethanol for a very sensitive reaction i would happily just make it via fermentation
or dig into the drinking stock, then just use the methylated spirits for making ether and the likes.
But the topic still carries merit atleast for curiosity sake, I mean come on surely you haven't atleast considered how pure you could make that stuff?Pumukli - 17-5-2019 at 03:38
Back to the topic: once I tried dissolving NaOH (a few percent) into the stuff and then added a few grams of kitchen Al foil pieces. The content of
the flask was stirred with a magnetic stirrer. Reaction was fairly vigorous. The addition of the foil took 1-2 hours, expect heavy bubbling, frothing,
anything.
With the help of Al foil one could remove all water and maybe reduce the MEK to sec-butanol. Sec-butanol boils around 100 C, hence the conversion
-theoretically- would give you 20-22 C difference in the boiling points. With a fractionating column it may be possible to get pure (absolute!)
ethanol from the "sludge".
The smell of the stuff after this treatment changed appreciably, maybe the reduction was successful, I don't know. I just distilled (without column)
the contents of the flask. I don't have a decent column so I did not bothered.
I think MEK can ruin the smell/taste of ethanol even at 0.02% concentration, so this method even with 99% conversion (I doubt that rate) would yield
an undrinkable spirit. But that spirit would be much better suited for chemical reactions and would be absolute (in the sense of free from water)
ethanol!
Anyway it is just something one can ponder about. AJKOER - 18-6-2019 at 07:12
Perhaps a different approach in the case of other organic additives that CH3OH, add Mg to create the magnesium ethoxide and hydrogen. Isolate the
solid salt free from moisture (assuming no other magnesium salts are formed).
When in need of the ethanol for an application, add water (which can react violently liberating pure ethanol and Mg(OH)2).
Note: This is immediate prep for the ethoxide and not ethanol via distillation (which may be an important legal distinction).
Obvious economic issue is the cost of the magnesium source metal.Pumukli - 18-6-2019 at 07:27
I read somewhere that ethanol and higher alcohols are hard to convince to react with magnesium. Only methanol reacts with it relatively readily.
I've seen it myself: I could make Mg-methoxide but only after a few drops of ethylene-bromide were added to the Mg - methanol mixture to activate my
magnesium. My denatured ethanol did not react with the same Mg.AJKOER - 18-6-2019 at 07:54
Surface area of the Mg makes a difference, and surface preparation by either pre-washing it with dilute HCl, conc NH4Cl(aq), dibromoethane, stirring
with added glass shards to expose fresh metal, or crushing magnesium turnings, ..., are among many other recommendations presented by researchers
available at: https://www.researchgate.net/post/Does_anyone_know_the_best_...
I read somewhere that ethanol and higher alcohols are hard to convince to react with magnesium. Only methanol reacts with it relatively readily.
I've seen it myself: I could make Mg-methoxide but only after a few drops of ethylene-bromide were added to the Mg - methanol mixture to activate my
magnesium. My denatured ethanol did not react with the same Mg.
Have you tried this with your denatured ethanol, Mg and ethylene-bromide?AJKOER - 5-8-2019 at 04:39
Came across a reference (see full discussion at
https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Alcohols/Properties_of_Alcohols/Acidities_of_Alcoho
ls ), to quote in part:
"When considering alcohols as organic reagents, pKas are often used because they reflect reactivity in aqueous solution. In general, alcohols in
aqueous solution are slightly less acidic than water. However, the differences among the pKas of the alcohols are not large."
where the cited PKa of methanol was 15.5 versus ethanol of 15.9. And to quote further:
"There are many sites on the internet with explanations of the relative ordering of alcohol acidities in aqueous solution. The general explanation is
that the larger substituents are better electron donors, which destabilize the resulting alkoxide anions. Because hydrogen is least donating of the
substituents, water is the strongest acid. Unfortunately, although this belief persists, it is incomplete because it does not account for the
gas-phase results. The problem with the electron donation explanation is that it suggests that the order of acidity is due solely to the intrinsic
electronic effects of the substituents. However, if that were the case, the electron donating effect should also be evident in the gas-phase data.
However, the relative acidities in the gas phase are opposite to those in aqueous solution. Consequently, any interpretation of the acidities of
alcohols must take the gas phase data into account.....The inversion of the acidities of alcohols between the gas phase and aqueous solution was
pointed out by Brauman and Blair in 1968.[3] They proposed that the ordering of acidities of alcohols in solution is predominantly due to the
combination of a) polarizibility and b) solvation, and that the electron donating ability of the substituent does not play a significant role.[4]"
The above comments should be taken into consideration in any suggested chemical base separation path between methanol and ethanol. Tsjerk - 5-8-2019 at 07:04
The difference in pKa is only relevant for reactions without a catalyst, at least for determining whether or not the reaction will proceed.
Also reactions running at reflux will not care too much about a pKa difference of 0.4, as the speed of the reaction will be mostly compensated by the
higher temperature.
I don't know of a reaction that does not run with either ethanol or methanol, but that does with the other, where no catalyst is present. But I'm
happy to be corrected. Pumukli - 6-8-2019 at 05:34
No, I did not try the rxn with ethylenebromide. I simply didn't want to contaminate the ethanol with some unreacted carcinogene. (We are talking about
hypothetically drinkable ethanol, right? Using a carcinogene would defeat the purpose of the whole procedure. Even if we don't want to drink that
ethanol in the end.) Tsjerk - 6-8-2019 at 05:55
The reason I asked is because you're claiming a difference in reactivity between methanol and ethanol, and then use an example were you use a catalyst
and compare this with a reaction without a catalyst... A little bit like comparing apples with pears.
