Identifing Methanol - test?

Matt Simis

I have 2 gallon drums of excess stock from a Model Shop sold to me to clear as methanol. Unfortunately these are unmarked drums, so its always been at the back of my mind that perhaps these isnt even methanol.

They have sat outside the house for 6mths and were in storage for about the same in the Shop. Im going to use it mixed with Water in a Car (Water-Meth injection) so it shouldnt matter if its spoiled with some water by now.


Anyway I can put my mind to rest?

SOL

I'd say run an NMR of it, but unless you know someone who works in research chemistry thats not really an option...

Matt Simis

The other likely candidate for this liquid is ethanol.. so really only need a test that differentiates ethanol and methanol?

Professor_Fink

Matt Simis wrote:

The other likely candidate for this liquid is ethanol.. so really only need a test that differentiates ethanol and methanol?

Just work out the density of the liquid you have (mass/volume), and compare it to the density of the candidates.

DemocAnarchis

You could do a comparative tlc test with a pure sample of methanol & ethanol?

j4vier

a mass spectrum will differentiate the two of them since the peaks that will be seen depend on the molecular mass of the fragments .most analytical labs will have GC-MS so that would be easier to get ur hands on rather than an NMR.
Otherwise if you are sure that only ethanol and methanol could be present,
even a carbon 13 test will make it clear which one is present.

Mucco

Methanol and ethanol are probably too small to see on an MS. TLC wouldn't show them either. Densities are probably too similar to differentiate. A referenced GC trace would do, or a proton NMR, or refractive index (maybe), or boiling point. Rough and ready would be smell (careful, methanol is toxic).

If you don't have access to a lab, boiling point might be best.

MeOH
refractive index n20/D 1.329
bp 64.7 °C

EtOH
refractive index n20/D 1.3600
bp 78 °C

Professor_Fink

Maybe we should stick to practical solutions here. NMR, ESR, mass spectromity, optical absorbtion spectra, neutron irradiation, freezing and using an AFM, using microwaves to break specific bonds and any other over the top physical or chemical technique probably aren't going to help him. Let's live in the real world.

Boiling point, density, melting point, etc. are things you can actually do in you kitchen.

ApeXaviour

Boiling point would be the way I'd go. Put a bit in a pot over a (non-gas) hob, with a thermometer in it, I'd also make sure the ventilation fan is on. You can get electric thermometers in the two-euro shop these days (look basically like this though a little less sophisticated).
Even if it's a mixture of say water-methanol. It will appear to boil at around 65C for a while until all the methanol boils off, then quickly rise to 100. You'll see this yourself on the thermometer. If at any point it stops on this rise, say at around 80C, and stays there for a while then you could well reckon there's a good portion of ethanol in there.
Propanol bp is ~97.5 so it'd be a little difficult to tell if theres much of that in it if there's also water there.

Matt Simis

Thanks all, the practical test sounds pretty good. I assume only a small portion of liquid will be required/advised, 100ml or so?

Matt

DemocAnarchis

You just need enough to cover the bulb of the thermometer. Touching the bottom of the pot will cause a massive error in the readings, as you will be reading the pots temperature, not the liquid, so i'd suggest filling the pot with some water, and placing a second, smaller glass/plastic container inside, with it containing the methanol/ethanol. Obviously, this cant touch the base or sides of the pan either, so logistically might be a bit fiddly, but should provide much more even heating.

SOL

What ever you do
DO NOT BOIL 100ml, or any other ammount of Methanol without a fume hood and very high powered ventilation

SOL

if you do you may very well kill yourself, but more likely you will just do irreversable damage to your eyes, and internal organs. if you want a quick test and the only alternative is ethanol have a careful smell, Methanol is prettymuch odourless, if it is Ethanol it will ahve a sweet smell, that said if it smells of ethanol it may be Methylated spirits, which has a few % methanol, an so is somewhat toxic... so don't drink it. (Ever heard the phrase blind drunk?)

Matt Simis

Thanks for the warning, though I can assure you Im not planning on drinking it!
Can you confirm the methanol smell? I was led to believe it (not ethanol) smells slightly sweet , as does this liquid which would be unfortunate. However I have found lots of info on line that contradicts itself, "Methanol has grape fragrence added, smells sweet, methanol is odourless, ethanol smells sweet, ethanol is an odourless liquid".

One other potential test Ive considered is dropping Aluminum in a tub of it and observing. Methanol is meant to be quite corrosive to Aluminums oxide coating while ethanol isn't. Any thoughts?

SOL

Well I was in the lab this morning and Methanol was still odourless to me while ethanol still smells like a cheap bottle of vodka... dunno about the aluminium test, give it a go I suppose... I'd imagine if it has that smell what you have is methylated spirit, i.e. Ethanol with some Methanol in it, does it have a colour? (Most Methylated spirits come with purple dye in them to make sure people don't try and use it as ethanol)

Sev

What about boiling 100ml of methanol outside on a relatively windy day? Would that be ok?

ApeXaviour

I used to distill and I remember the "heads" of the distillate would always have a much sweeter smell (good portion of methanol) than the main run (mostly ethanol). According to wikipedia it has "a distinctive odor that is somewhat milder and sweeter than ethanol".

If methanol is so poisonous (it's not that poisonous) and yet volatile, then I would have thought boiling a small amount of it outside on a windy day (as sev said) is less dangerous than sniffing it directly?

Professor_Fink

ApeXaviour wrote:

If methanol is so poisonous (it's not that poisonous) and yet volatile, then I would have thought boiling a small amount of it outside on a windy day (as sev said) is less dangerous than sniffing it directly?

I have to agree on this. Methanol is not something you should go about taking swigs of, but its not as dangerous as SOL is making out. Wikipedia has more: http://en.wikipedia.org/wiki/Methanol#Health_and_safety

SOL

Look, you might get away with what ever but it is not a good idea and I wouldn't like to see you make a mess of yourself, and I use both solvents every day, and to mee methanol is odourless, and ethanol smells like a bad night out, and as for ste, **** off, if you do it out doors you will need a heat source and if it is electric be careful but if it is gas you will probably set it on fire and methanol flames are virtually invisible in bright light, so you see the problem

Red Hand

Refractive index is the safe and cheap way to identify, so long as you know that that what you have is definately not a composite.

Matt Simis

Jeremiah 16:1 wrote:

Refractive index is the safe and cheap way to identify, so long as you know that that what you have is definately not a composite.

Not looking for cheap, looking for easy..

Red Hand

Ha, it is easy! Just dropper one or two drops onto the viewing plate, line up your sights, compare the number you read to the number given for methanol in any Aldricht volume and hey presto-its either methanol or not.

SOL

Yes, but where do we find such a "viewing plate"?

Skyhawk

DemocAnarchis wrote:

You could do a comparative tlc test with a pure sample of methanol & ethanol?

Really ????

Gas chromatography is your answer.

SOL

Yeh, just see how they elute a known sample against reference ethanol and methanol... but it probably wouldn't be so reliable,

SOL

Did you ever get an answer then?

John_C

It might be an old wive's tale but does milk curdle in methanol but not ethanol?

oneeyedsnake

Just give some with sleeping pills in it to a down and out,tell him its vodka,come round the next morning beforre he wakes up,if he starts screaming I'm blind,then you've got methanol, punch him in the face and make a swift exit.