[isojorgon]

Hello,

I have a somewhat stupid question to which I can't find a straightforward answer.

To all you experienced chemists: would you rather use methanol or acetone as your basic bench solvent?

As far as MSDS', both solvents have similar hazard classifications and toxicological effects, but methanol seems to have greater long-term exposure risks. I suppose my actual question is: is methanol dangerous enough that it's worth making the case to my teacher for switching to acetone?

Cheers,
Isojorgon

[Corribus]

No, methanol is perfectly safe. No worse than rubbing alcohol, really. Just follow standard safe handling procedures for organic solvents.

They are also not the same solvent. Acetone has to be handled with a little more care because it will damage a lot of surfaces that methanol will not. As I once found out the hard way.

All things on balance, I'd rather use methanol unless I needed something a little more aggressive for stubborn organics.

[wildfyr]

Interesting. I would consider acetone my default solvent for exactly the same reasons. It has more general solubility, especially since I work with polymers, and therefore dissolves more things, which as a solvent is exactly what I want from it. I also see it as somewhat less toxic, as 10mL of methanol ingested would blind you, but acetone would probably just make you feel like crap.

[P]

I've never liked methanol - we were told at school that it was toxic and I have carried that with me since. I like acetone because it is powerful and volatile. I think it can accumulate in the kidneys or something over prolonged use, but I didn't think it was toxic like methanol. I have never worried about getting little splashes of acetone on me   -  maybe I should.

[Arkcon]

As we move towards greener chemistry, I think most places would like to reconsider having a bench solvent at all.  What's it for?  If you need to wipe down a bench, have a plan taking the needs in mind and execute it.  Just having some solvent around for "wiping down" really isn't in style anymore.  IMHO.

[Corribus]

Interesting. I would consider acetone my default solvent for exactly the same reasons. It has more general solubility, especially since I work with polymers, and therefore dissolves more things, which as a solvent is exactly what I want from it. I also see it as somewhat less toxic, as 10mL of methanol ingested would blind you, but acetone would probably just make you feel like crap.

Are you ingesting 10 mL of any solvent routinely?

[wildfyr]

Ethanol

In all seriousness I'm not suggesting its likely to ingest it, I am simply trying to set a benchmark for relative toxicity. I don't hesitate to work with both of these every single day.

[isojorgon]

Hello,

Thank you all for your helpful responses. I've shown them to my teacher, and it sounds like we should probably consider switching to acetone. FYI, we're not using the solvent to wipe down the bench, but to clean tools and surfaces between handling samples so we don't cross-contaminate.

Best wishes,
Isojorgon

[DrCMS]

While the reported LD50 values of methanol and acetone are similar that does not paint a true picture of the human toxicity where methanol is worse than acetone.  The LD50 data is usually done on rats but rodents metabolise methanol by two different metabolic pathways.   Primates only use one of those and the metabolite is very bad particularly for the optic nerve.  The UK maximum workplace exposure limits WEL are lower for methanol than acetone for this reason: 

15min short term exposure limit 250ppm Methanol  or 1500ppm Acetone
8hr time weighted average limit 200ppm Methanol  or 500ppm Acetone

Based on the rat data methanol is a reproductive toxin but it does not officially get that H361d classification because in primates the levels that cause birth defects in rats kills the mother before they can give birth.

[wildfyr]

If this is biology, the standard is to use isopropanol/water btw

[Arkcon]

Actually, for microbiological cross-contamination, there are abundant commercial sterilants available.  They are mixtures of a variety of chemicals and cleansers -- here's a list of just a few: https://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/ReprocessingofReusableMedicalDevices/ucm437347.htm

But the O.P. has not yet troubled themselves to tell us conclusively what they want to clean.

As DrCMS: explained, there's no conclusive all size fits all interpretation of toxicity.

[OrganicDan96]

in the lab i used to work in (an organic research lab to be fair) we used acetone for washing, probably used far more than we needed. we would get through like 9 L a week. I would definitely go for acetone as a bench solvent.