Sciencemadness Discussion Board

Troublesome disposal of DMSO/DCM mix

jenijjun - 25-9-2021 at 00:44

So I discovered a waste bottle that should be dealt with and it contains dimethylsulfoxide, dichlorometane and 95% ethanol.

Can't really burn it right away because of the DCM and phosgene hazard, and evaporation is a pain too because dimethylsulfide reeks like crazy, I can smell it everywhere.

Do you have any idea how to deal with this?

unionised - 25-9-2021 at 05:26

There shouldn't be much dimethyl sulphide in DMSO (it smells like there is a lot because the smell is so strong).
Adding something like a solution of copper sulphate will precipitate any thiols.
I think using copper (I) chloride might trap the sulphide too.

Try it on a small scale and see it it works.
And then you can distil out the DCM.
Another option would be to add water until the DCM forms a separate layer from the alcohol/ water/ ethanol mix.
That only works if there's quite a lot of DCM.
But if you can separate it you have solved the phosgene etc problem.

Burning DMSO will generate a lot of SO2 which is toxic.

If the DCM separates out it will carry some of the sulphide with it.
But you can remove that by washing with bleach.

Fulmen - 25-9-2021 at 06:28

Mail it to some random governmental institution and let them sort it out ;-)

unionised - 25-9-2021 at 06:43

Quote: Originally posted by Fulmen  
Mail it to some random governmental institution and let them sort it out ;-)

That might have worked a while ago, but these days it's possibly going to be treated as terrorism.

karlos³ - 25-9-2021 at 12:47

I would try adding water to cause phase separation and then first, add some bleach against the Me2S....
The aqueous phase should be pretty safe to go down the drain then(yes, small amounts of DCM containing, but the ocean is far worse in terms of halocarbons... or are you dealing with waste vat(s) and not bottle(s)? :o).

The DCM can then be separated off and reused by distillation, which I would recommend.

At least that is what I did in similar situations, just lately had to work with a bromohydrin synthesis in aqueus DMSO....
After the first portion of NBS added to it, I remembered why the last time I did this synthesis was 2,5 years ago.... while working it up, fully experienced this :D

After getting rid of all the smelly liquid wastes though, what was left was a strong desire for cauliflower(I kid you not) and I ate 750g of them with nothing than butter and a few sprinkles of salt and pepper two days later :o *
And I assure you, I hate the smell of Me2S than anyone else does.... but the tiny little hint of cauliflower must have infected my pleasure center or whatever because it was a really, really strong desire :D
I hope you find it as funny as me(of course I quickly thawed them up in the microwave in advance of devouring them, butter, saltnpepper and a burned roof in the mouth, did not eat them raw... and I definitely had no time to cook a fresh head of it, oh no sir, I had to devour it as quick as possible).

*Also, maybe some sprinkles of that liquid maggi stuff might have been involved... I put it on everything.... :D

E: bleach, simple hypochlorite solution, oxidises dimethyl sulfide to, I think MSM(methyl methanesulfonate) which is free from any smell.
After a sufficient amount has been added, the smell of the solution will disappear and then you only have to dissipate what already is floating around in a gaseous state.

Also, just thinking about said reaction which caused the great cauliflower-crave, made me think about how tasty a kilo of cauliflower, buttered, and cooked just right would be... I would have two days of farting fun too when I'm alone....
Dimethyl sulfide is not that bad as a chemical!(he said, after having worked not long ago with it, but the memory already muddied up....)
I guess I should have said, cauliflower is not a bad smelling vegetable(don't mention brussel sprouts though...).

[Edited on 25-9-2021 by karlos³]

Tsjerk - 25-9-2021 at 14:07

Flush it down the drain when what you're working with is less than a liter.

unionised - 26-9-2021 at 05:04

If you dump a litre of dimethyl sulphide into the drains you will be in trouble.

karlos³ - 26-9-2021 at 08:47

Quote: Originally posted by unionised  
If you dump a litre of dimethyl sulphide into the drains you will be in trouble.

Hypochlorite, as said :cool:
MSM is not bad at all.

macckone - 27-9-2021 at 06:50

add oxidizer, separate and distill.
DMSO and DCM should not be flushed down the drain.
Ethanol and MSM are fine.
MSM is used as a supplement, so that is no problem.

steel wool is good at binding to sulphides.

BluBoirt - 28-9-2021 at 05:03

If I remember correctly mix of hydrogen peroxide and Fe2(SO4)3 on daylight can destroy dichloromethane as well. (someone please correct me if that doesn't work though)

[Edited on 28-9-2021 by BluBoirt]