Hi folks!

DCM is probably one of the less used solvents over here at the nexus as it's not really essential for any extraction listed on this site. Though if you're like me and like to have a good list of things at hand for any eventuality, you probably read that DCM is great for defatting and extracting stubborn molecules.

I came across a couple of 500ml bottles of this stuff about 6 months ago and opened one of the bottles that was stored for purchase in a HDPE bottle in a melt-seal plastic bag. I used about 50ml or so and put it in the cupboard with the lid screwed on tighly and haven't used it since. I just had a look at the bottle this morning and it's now half empty. I checked the lid and the seal mechanism was still intact. The bottle also contained a lot of pressure and let off a little hiss when the lid was removed.

Now I'm hoping that 250ml of DCM evapped slowly over 6 months doesn't have any serious health risks, but more to the point what's the best way to store this sneaky evaporating fiend?

I recently bought 5L of DCM and I agree its a wonderful solvent.The plastic HDPE2 tub had a thickish layer of cardboard-type stuff with a foil surface;the screw-on lid went over this.

I keep my DCM in its original opaque tub under the stairs where its dark and cool;after opening it, I simply got some good old aluminium foil, folded it over several times and shaped it to resemble the cardboard/foil thing that originally came with it, place this over the aperture and then screwed the lid down good and tight.Ive not noted any loss in volume using this approach.Just dont make your foil cover too thick as this can impede the screw thread for the plastic lid.

I keep DCM in the original glass bottle which I put into a cardboard box.

Not to derail but have any of you used DCM in a MHRB extraction ? Got a few questions (either thread or PM).

Chloroform and Dichloromethane typically need to be mixed with a stabilizing agent for long term storage. Other ways to prevent degradation is to store it in dark away from light and air.

Either way the degradation products include hydrochloric acid and phosgene. The 'hissing' sound may be explained by the formation of such compounds or a simply a pressure build up. So yea halogenated solvents can be quite dangerous when they degrade.

Ethanol is one solvent used to stabilize chlorinated solvents. Requies about 1% pure ethanol to extend shelf life considerably. Amylene is the most common preservative used in DCM. See if its in your bottles. Its a small hydrocarbon and is in low concentration so it won't interfere with extractions.

Your sister used to purchase DCM in 4l metal jerry cans. DCM has a very low boiling point so If the temperature goes up after sealing the lid, sometimes the jerry can was bulging due to the vapour pressure. But as far as sister is aware there was no loss of solvent. There was a foil backed cardboard chip in the metal lid to seal it.