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Murexide
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Dichloromethane
DCM is a common solvent, and my purpose is for caffeine extraction from caffeine pills (probably the most common beginner amateur use for DCM), as
well as for coagulating AgCl suspensions in certain argentometric titrations (chloroform replacement). Apparently, it smells somewhat sweet, but it is
dangerous at levels where it can be smelt.
The downside to DCM is that it is probably carcinogenic. Apparently it is less so than chloroform, which makes it more suitable (as well as
significantly easier to obtain in Australia). It is sold as paint stripper 87% dichloromethane, which is apparently a liquid rather than a gel
(significantly more convenient for distillation). Separation from ethanol can be achieved with CaCl2/H2O complexation
The other problem is storage and hand protection. Currently, in its paint thinner state it is in a metal can and it can be stored at and slightly
above room temperature without explosion or leakage hazards. However, in its pure form it must be stored in either a metal container (risky, due to
potential compatibility issues) or glass reagent bottles (explosion hazard unless in a freezer, which is not available, and the type of plastic cap is
also an issue). Apparently, DCM creates a strong burning sensation upon contact, so it would be wise to use gloves. Unfortunately, DCM penetrates
almost all common glove types. It is interesting that despite the problem of its high volatility and penetration, it is suggested as a chloroform
replacement.
If DCM experiments are conducted outside for select experiments, how high is the carcinogenic risk of DCM? It would need to be distilled from a retort
connected to a Ahlin connector (I am certainly not distilling a compound bp. 40C with an air condenser!), so some vapours would be released.
[Edited on 26-12-2018 by Murexide]
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DavidJR
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Why would glass bottles present an explosion hazard?
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Murexide
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DCM is very volatile even at room temperature, as it’s boiling point is 40C. If stored for long periods of time in glass bottles especially at
slightly above room temperatures, pressure (of its vapour) can build up and then cause glass bottles to explode.
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Justin Blaise
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I don't think you're going to have any compatibility issues with storage in a metal can. It comes in a metal can, for one, and it's not so reactive
that the surface of a metal can will appreciably reduce it. Unless your can is made of sodium. You could even just clean out the original container
and put the purified stuff back in there.
Hand protection is tough. I've gotten DCM drops on my gloves and then felt burning shortly after. Best solution I could come up with was to work
carefully and quickly remove gloves after I notice spills. You get a couple seconds of protection, even if DCM can penetrate, and you can use that
time to quickly get your hands out of there. According to this source https://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@te... there is inadequate evidence to say it's a human carcinogen. So just distill it
outdoors or in a fume hood and you'll be fine.
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Murexide
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Cleaning the original can is certainly an attractive option given that the formula is liquid and not gel so it will be easier to clean out (water,
base would be preferable as it will destroy DCM but metal can will also be destroyed). With some luck, I can probably extract out 250-300mL of the
435mL theoretical DCM, the azeotrope 95% DCM 5% ethanol. The ethanol in fact is probably necessary to keep as a stabilising agent (although DCM is
much less risky than chloroform in terms of phosgene formation, it is nevertheless a good idea). So 50% fillled should not provide too much of an
explosion hazard, considering it will be used soon after and destroyed after with aqueous NaOH.
For the distillation, I will probably attempt something similar to my nitric acid distillation by using remote switching of the hot plate (of course
using a hot water bath) situated outdoors from indoors. This should limit DCM inhalation significantly. Even though it says there is inadequate
evidence of it being a confirmed carcinogen and is certainly less so than benzene, it does say it is a probable carcinogen (confirmed for lab
animals), so it should probably be treated cautiously.
Thick latex gloves seem to be the best option, as they extend the period of time between exposure and contact perhaps from a few seconds to 10 or so
seconds. That should be enough time.
Edit: The volatility and capacity of DCM to escape the container when not cooled in a freezer is the main reason I prefer to limit use and destroy
soon after
[Edited on 26-12-2018 by Murexide]
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Deathunter88
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Stop being so paranoid! The fact that it's sold as a consumer product DESIGNED to be spread over large areas and evaporated means that the exposure
you will get from working with it as a chemistry reagent is perfectly safe. I personally wouldn't even bother wearing gloves, since it evaporates so
rapidly wearing gloves is just going to trap it against your skin for longer.
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Heptylene
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You can use vented caps for glass bottles if you want to minimize the risk of explosion. It really depends on the temperature of your lab. If it's at
around 20°C you will be fine. Professional labs store DCM in glass bottles at room temperature.
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fusso
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I don't think storing in a metal can will make it explode. I live in a warm place and my DCM is stored in glass beer bottle. The lid is capped loosely
and has been sitting there for a year. It's still intact.
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Ubya
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where i live temperatures in summer can easily reach 35-40 °C, i expect to be hot as well in australia, so metal or glass container you still need to
keep it cool somehow. i'm distilling right now all the solvents i found OTC that contain DCM, i had to wait so long because tadaaa i didn't have the
right container (i will be using a glass bottle used for solvents i found while hiking on the italian Alps, really random i know, and to the cap i
added a teflon disc).
i think you are a bit paranoid too, sure you don't want to breathe chlorinated solvents all day but a few whiffs won't give you cancer, if DCM does
this reaction to you i don't know what benzene would do.
ps gloves are not an instoppable barrier, they are there just to slow contact with skin, if something spills on them, you must change them anyway
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feel free to correct my grammar, or any mistakes i make
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DavidJR
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Quote: Originally posted by Deathunter88  | | Stop being so paranoid! The fact that it's sold as a consumer product DESIGNED to be spread over large areas and evaporated means that the exposure
you will get from working with it as a chemistry reagent is perfectly safe. I personally wouldn't even bother wearing gloves, since it evaporates so
rapidly wearing gloves is just going to trap it against your skin for longer. |
I agree that it's pretty safe to use in a lab situation where you aren't evaporating large quantities into the lab atmosphere. However, I disagree
that it's safe as a paint stripper since there have been numerous deaths from people using DCM based paint strippers in poorly ventilated areas. This
is why it's banned in paint strippers in many places.
Re gloves, the only gloves which offer real protection against DCM are ones made from polyvinyl alcohol. They aren't suitable for general use though
because they are water soluble. Any other kind of glove offers at most a few seconds of protection. Keep this in mind if you're handling DCM solutions
of anything that is toxic or otherwise hazardous.
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XeonTheMGPony
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| Quote: Originally posted by Murexide | | DCM is very volatile even at room temperature, as it’s boiling point is 40C. If stored for long periods of time in glass bottles especially at
slightly above room temperatures, pressure (of its vapour) can build up and then cause glass bottles to explode. |
Guess no one has told my glass bottle this information, poor thing will be embarrassed, it's been sitting there and working for a year and some now
just doing its job!
HINT: Look up some thing called a PT Chart (Pressure Vs temperature)
Screw it here it is: https://en.wikipedia.org/wiki/Dichloromethane_(data_page)
[Edited on 2-1-2019 by XeonTheMGPony]
[Edited on 2-1-2019 by XeonTheMGPony]
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Mr. Rogers
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All the DCM I've ever bought came in a glass bottle.
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Dan Vizine
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Have you ever simply looked up sellers of industrial solvents in your town? I went to "Buffalo Industrial Solvents" and said that I wanted to buy
methylene chloride. The guys said "5 gallons, 60 bucks". I said fine.
I also simply walk into Riverside Chemical Company (a local JTB distributor) and just order what I want, be it PE, toluene, acetic acid, etc. You
don't need certification, identification, or company-affiliation to buy these commodity grade materials in NY.
"All Your Children Are Poor Unfortunate Victims of Lies You Believe, a Plague Upon Your Ignorance that Keeps the Youth from the Truth They
Deserve"...F. Zappa
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Herr Haber
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Gloves: nope. It'll go through the gloves yes. But not alone ! So I'd rather avoid gloves at all. The burning is tolerable in the beginning but after
a short while the only thing you want to do is wash your hands again and again.
Bottle: Not gonna explode. A media bottle is fine. I have my DCM in a media bottle, it survived last summer 35 degrees without a problem. I've had
some years ago from APC Pure delivered in HDPE bottle and THAT is bad.
Someone on the forum used to words "escape artist" for DCM. So true. The HDPE bottle was inside a plastic bag. I stored it, forgot about it and came
back months later to find an empty bottle. The bottle and plastic bag were intact and showed no sign 1 liter of DCM had gone through.
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woelen
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I read a lot of fear mongering in this thread.
DCM, stored in glass bottles forms no explosion risk. Period. Not even at very hot summer afternoons, when stored in a normal cupboard in the house or
a garage. You may get some pressure buildup in a bottle, but a normal glass bottle withstands quite some pressure. Think of bottled drinks like coca
cola in glass bottles. They have MUCH more pressure inside than you will ever get in your bottle of DCM.
DCM hardly is a skin risk. It evaporates very quickly, simply waving your hands for a few seconds removes the DCM. Using gloves is overkill or even
adds extra risk.
DCM is toxic, but it is not instant death in a bottle. I would worry about slow long-term release when this is in the same area as where you live on a
day-by-day basis, such as was the case with the 1 liter plastic bottle which lost all DCM over a period of a year.
Occassional spills on your hands are no problem. Clean DCM simply evaporates and is not quickly absorbed, because it is not water-soluble. Things may
become different if the DCM is used as solvent and contains other toxic compounds. Then a spill on your skin may be problematic, because the DCM is
gone in seconds and a thin film of the toxic compound remains on your skin. If that occurs I would wet a piece of tissue with DCM and quickly use that
to wipe your skin to get rid of most of the dissolved compound and then wash thoroughly with water and soap.
Again: use common sense, respect the things you work with, but do not fear them!
[Edited on 7-2-19 by woelen]
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S.C. Wack
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DCM is a skin irritant for sure though and it would not surprise me if it is absorbed...anyways, my last order of DCM came in typical quart cans, and
when I went to jug it up a year later, half the DCM was gone.
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zed
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Should be sealed tight with an inner metal plug.
Even high boilers, sneak away, if not properly sealed.
Back in the days, when such items were unrestricted in commerce, I weighed a 25lb can of Safrole after several years in storage. ~ 23 Lbs remained!
My theraputic Spray and Stretch, Freon spray bottles, though never used or opened, now stand less than 1/2 full.
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AJKOER
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| Quote: Originally posted by Deathunter88 | | Stop being so paranoid! The fact that it's sold as a consumer product DESIGNED to be spread over large areas and evaporated means that the exposure
you will get from working with it as a chemistry reagent is perfectly safe. I personally wouldn't even bother wearing gloves, since it evaporates so
rapidly wearing gloves is just going to trap it against your skin for longer. |
Industries operate based on what their legal department assessment as to acceptable degrees of legal liability. Bottom line, the probability of
lawsuits and the expected amount of settlement costs.
This is likely just poorly correlated to actual toxic levels relating to either short term or long term exposure, so don't derive any inferences of
presumed safety from the willingness of some local suppliers to sell DCM. A company's variation in behavior across the world is likely a better
indicator as to actual safety of a product, in my opinion.
[Edited on 11-2-2019 by AJKOER]
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nimgoldman
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I never had issues with DCM storage even during a hot summer (I use glass reagent bottle with and ABS cap).
Of course I periodically checked and vented the bottles, checking for overpressure.
I used DCM in several extractions, not caffeine but eugenol from clove oil, for example and distilled it many times.
I found that DCM sucked in lots of organic impurities and had to be purified beyond distillation (e.g. shaking with conc. sulfuric acid).
As for the hand spills, you can use two layers of gloves and immediately remove them upon exposure. Although DCM will penetrate them, it takes some
time.
The health hazards manifest for people who work with DCM routinely and breathe the vapours in closed areas. If you use it occassionaly with
precautions (good ventilation), you will be okay.
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DrP
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| Quote: Originally posted by woelen | I read a lot of fear mongering in this thread.
DCM, stored in glass bottles forms no explosion risk. Period.
[Edited on 7-2-19 by woelen] |
I can't remember if it was Dichloromethane or Diethylether... (I get them confused) but I have seen a 2.5L Winchester brown bottle of the stuff on a
bench just break apart without any warning at all right before my eyes. It just broke into 2 or 3 pieces right in front of me on the bench. It was a
warn day, but still. It did not explode though but would have been very nasty if there had been a naked flame on the bench. The guy using it cleaned
it up whilst I waited outside to call an emergency if he passed out from the fumes or sparked an ignition somehow.
It was very strange - as it was evaporating in such a large volume there was massive distortion of vision through the fumes - like looking through
heated air that is rising.
I wonder if the claims of explosion were due to the glass breaking as I described whilst there was a Bunsen flame open nearby - that could make it
look like the bottle just exploded I suppose.
\"It\'s a man\'s obligation to stick his boneration in a women\'s separation; this sort of penetration will increase the population of the younger
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Tsjerk
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DCM is not flammable. A bottle that just breaks is faulty to start with, it would break if it was filled with water.
Check this graph: https://en.m.wikipedia.org/wiki/File:LogMethylenechlorideVap...
Even at 50 it's pressure is just at that of water at autoclave running temperature. I can guarantee you I've run many autoclaves and often opened them
at running temp because I wanted to go home. Never any bottle exploded or broke while doing so.
Edit: a champagne bottle could hold it at 100.
[Edited on 13-2-2019 by Tsjerk]
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DavidJR
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| Quote: Originally posted by DrP | | Quote: Originally posted by woelen | I read a lot of fear mongering in this thread.
DCM, stored in glass bottles forms no explosion risk. Period.
[Edited on 7-2-19 by woelen] |
I can't remember if it was Dichloromethane or Diethylether... (I get them confused) but I have seen a 2.5L Winchester brown bottle of the stuff on a
bench just break apart without any warning at all right before my eyes. It just broke into 2 or 3 pieces right in front of me on the bench. It was a
warn day, but still. It did not explode though but would have been very nasty if there had been a naked flame on the bench. The guy using it cleaned
it up whilst I waited outside to call an emergency if he passed out from the fumes or sparked an ignition somehow.
It was very strange - as it was evaporating in such a large volume there was massive distortion of vision through the fumes - like looking through
heated air that is rising.
I wonder if the claims of explosion were due to the glass breaking as I described whilst there was a Bunsen flame open nearby - that could make it
look like the bottle just exploded I suppose.
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If it was dichloromethane, then even if there was a naked flame right beside it, you'd have no fire, because DCM isn't flammable.
Diethyl ether, on the other hand.........
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Loptr
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Dichloromethane in glass bottles all day long. I dont use anything else. I keep all of my solvents in similar bottles.
"Question everything generally thought to be obvious." - Dieter Rams
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Keras
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I have ordered a litre of pure CH2Cl2 which should arrive to me later this month (it is really cheap, even in a pure form, like
€8/litre). I’ll tell you in what type of storage container I get it, if you want.
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DavidJR
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I paid £9.50 for 2.5L of HPLC grade DCM, and like all of my solvents from that supplier, it came in an amber glass bottle.
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