itsafineday
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adding nitrogen to dcm /chloroform
Would adding nitrogen from a tank to a bottle of dcm or chloroform help to increase shelf life?
I don't have a valve to evacuate and then fill the bottle I plan on just putting the hose end into the uncapped bottle , releasing gas for 10
seconds or so and then capping the bottle.
Also, how dangerous would a bottle of chloroform be after about 6 months or a year sitting in a closet at 27-30 c max ?
I am seeking to level up my Chem skills. Corrections welcome! All mentorship in madness appreciated.
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DavidJR
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Probably would help, yes, but I don't think it's necessary. I'm assuming though that you are just concerned with the safety aspect of phosgene
formation, rather than worrying about trace amounts affecting sensitive HPLC/GC analyses etc.
Checking my commercial solvents, the dichloromethane was supplied stabilized with 0.1% methanol and the chloroform was supplied stabilized with 0.5%
ethanol. I haven't noticed any hay odour or anything like that after storage in amber glass - over a year for the chloroform in a part-empty bottle.
My lab is quite cold for most of the year though. I haven't conducted any specific analysis for degradation products though.
If you made the chloroform yourself I would definitely add 0.5% to 1.0% of ethanol. I probably wouldn't worry about dichloromethane even if
unstabilized, because it is a lot more stable. Store them in a tightly-capped amber glass bottle away from sunlight.
[Edited on 11-12-2019 by DavidJR]
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itsafineday
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Thanks DavidJR. That was a very helpful answer.
I am seeking to level up my Chem skills. Corrections welcome! All mentorship in madness appreciated.
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DavidJR
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For peroxidizable solvents like diethyl ether and tetrahydrofuran, it is probably more beneficial to purge the headspace with inert gas. Especially if
the solvent does not contain a stabilizer like BHT. Peroxide formation in ethers can be quite rapid.
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LearnedAmateur
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The worst thing that’s ever happened to me with DCM, is that a small HDPE bottle (not completely airtight) with ~50-100mL, evaporated over the
course of about 2 months.
I’d had a litre of the stuff for around 8 months, no noticeable change in chemical properties (as a solvent, nor via the trusty old smell test). Not
something to worry about like you would with ethers.
[Edited on 7-1-2020 by LearnedAmateur]
In chemistry, sometimes the solution is the problem.
It’s been a while, but I’m not dead! Updated 7/1/2020. Shout out to Aga, we got along well.
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draculic acid69
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I had an old 4litre can of the stuff an by the time i got to the bottom of it 2-3yrs or thereabouts there was a rusty water layer in the bottom.the
stuff on top was still good
though.worst case scenario is some breaks down into water methanol and HCL with some phosgene bubbling out over the years.dont keep it in your living
space that's all.
This takes years to happen so don't worry about it too much.
[Edited on 7-1-2020 by draculic acid69]
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