Methanol

[Guest VooDoo]

I'm currently running methanol at temperatures below zero (-30°C). And when I went and checked the reservoir for the methanol I found some white residue on the metal (aluminium) and it had eaten through some plastic. Now is this normal methanol behaviour? The methanol is mixed with water.

 

I won't go into detail about what the system is being used for.

[budullewraagh]

this is most likely a result of the reaction between aluminum and water, forming aluminum hydroxide. methanol's acid dissociation constant is really high so this probably has no effect whatsoever

[Martin]

this is most likely a result of the reaction between aluminum and water, forming aluminum hydroxide. methanol's acid dissociation constant is really high so this probably has no effect whatsoever

 

many years ago a group I was in was studying options for synthetic fuels and we studied methanol

 

and my memory is not too good of the details, but i remember someone telling me that some parts of automobile engines (or periferal like tank and fuel line or pump) would need to be redesigned with differnt material because methanol did SOMETHING.

 

I curious now and would really like to know. What is there that gasoline doesnt corrode but that methanol does?

 

I trust budu in general but I would like some online source for it, if possible.

[budullewraagh]

thing is, i can't see any reason for aluminum to react with methanol. think of it; the methanol lacks significant negativity.

you'd never see the aluminum attack in a way leaving Al(3x bond)C-H

you wouldn't see the aluminum attack in a way leaving Al(H3CO)3 either because the H3CO- anion is harder to form than the OH- anion with the Al replacing the H

[Silencer]

I don't see why the H wouldn't drop off from the O, wouldn't it be just like what happens with water? And I thought my teacher mentioned that being a donor proton when we were messing with 2-propanol and inks (different substances, but same OH bond).

 

Maybe there were impurities in the water? Did you use tap water, VooDoo?

[budullewraagh]

exactly and thats why methanol wont react with aluminum

[Silencer]

What about the eaten-through plastic?

[budullewraagh]

depends on what sort of polymerized organic it is

[Technologist]

Aluminum hydroxide is a white solid. Anhydrous methanol is very corrosive to most metals I do believe, but in the presence of water methanol is much less corrosive. If chlorides are present methanol will corrode aluminum quickly, forming aluminum methylene chloride. I’m can’t recall its physicals properties. Did you use tap water?