Sciencemadness Discussion Board - Dichloromethane ?

Dichloromethane ?

Wolfram - 8-11-2003 at 16:05

Do you know any way to do dichloro methan, diiodo methan, or dibromo methan at simple lab?

[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: subject "Dichloromethan" → "Dichloromethane"]

[Edited on 31.8.13 by bfesser]

Rhodium

PrimoPyro - 8-11-2003 at 16:18

http://www.rhodium.ws/chemistry/ch2br2.html

http://www.rhodium.ws/chemistry/ch2i2.html

EDIT: You may recieve a forbiddon error at these links. This is due to server maintenence and tweaking, and won't last long. If you get this error, check back in a half hour and it should work.

[Edited on 9-11-2003 by PrimoPyro]

DDTea - 8-11-2003 at 20:26

The synth of Methylene Chloride can be bought OTC as a solvent.. Check the Hardware stores, and read the labels on their solvents. It may be mixed with Toluene or something, but it should be possible to separate the two (MeCl2 is very volatile).

Organikum - 23-11-2003 at 10:18

paint remover.
1 liter = 0,5 liter DCM by distillation.

unionised - 23-11-2003 at 12:12

Last paint stripper I used had methanol in as well, how do you break the azeotrope

vulture - 23-11-2003 at 14:14

Adding a bit of toluene?

EDIT: Even better, it seems that NH4NO3 dissolves in methanol.

[Edited on 23-11-2003 by vulture]

unionised - 23-11-2003 at 15:00

I'm sorry, could you explain that please, I know they add toluene or benzene to the ethanol water azeotrope and redistill it, but I'm not sure it will work in general.

As for the NH4NO3, so it dissolves in methanol, it dissolves in water too. So what?

vulture - 23-11-2003 at 15:27

Outsalting the methanol. The methanol and DCM will form 2 separate layers --> gone is the azeotrope.

Same thing goes for toluene. It will mix with the DCM (IIRC) and separate it from the methanol.

[Edited on 23-11-2003 by vulture]

unionised - 23-11-2003 at 16:17

Toluene mixes with both, come to think of it you might try isooctane or cyclohexane which don't mix with methanol. I'm not sure if they would azetrope with the DCM anyway.
The NH4NO3 is interesting; salting out works for some materials. The one I use it for most often is unmixing acetonitrile and water by adding common salt. The problem is that if you add methanol the liquids don't separate; the salt just doesn't dissolve very well. I might try the DCM/Methanol/ Nitrate mix in the lab if I get a chance.
I have a vague memory that you can't use CaCl2 to dry alcohols because they solvate it. I wonder if that migt strip the alcohol from DCM.

vulture - 24-11-2003 at 07:55

Methanol has a higher dielectric constant than most alcohols and I'm pretty sure there are a lot less ionic salts that dissolve in ethanol.
I don't know if CaCl2 dissolves in methanol though. It would be nice, since it's dirt cheap.

You're right about toluene not working.

Doh! I forgot the most obvious method of all. Given that there is no emulsifier or water in the mix you might want to try to flush it with icecold water.

[Edited on 24-11-2003 by vulture]

unionised - 24-11-2003 at 14:24

CaCl2 does dissolve in methanol, but that's not the point.
If you wanted to remove traces of water from DCM you might add CaCl2 and filter off the hydrate. If you want to remove methanol form DCM you could shake it up with CaCl2 and filter off the "methanolate" (Not sure if that is a word). At any rate you could filter off the complex of CaCl2 and methanol.

Mendeleev - 2-10-2004 at 15:36

Why not add water? Methanol will go into the water, and DCM will separate out on the bottom. Then distill the DCM, dry with CaCl2, filter, and redistill. Also:

http://www.eurochlor.org/chlorsolvents/publications/methyl.h...

This site says under section 2 summary:

"There is no evidence that methylene chloride causes cancer or has any other serious effects in workers exposed long-term to relatively high concentrations. "

Are they braindead, or trying to kill us? DCM is listed as a known carcinogen. Bad carcinogens such as benzene are referred to as possible carcinogens. If it says it is a known carcinogen that means it's even worse. Did i get something wrong? Are all the paint stripper cans wrong? Is it not a carcinogen?

neutrino - 2-10-2004 at 17:43

I have seen it referred to as a possible carcinogen in the handfull of MSDS sheets I have seen. Where is it listed as a known carcinogen?

Mendeleev - 2-10-2004 at 19:54

On the back of every paint stripper can I have ever found. I could have had it the other way, benzene may have been the known, and DCM the suspected, but I still find the claim that workers exposed to high long-term concentrations are safe, to be a little incredulous.

[Edited on 3-10-2004 by Mendeleev]

neutrino - 2-10-2004 at 20:07

Those claims might be eggadurated for liability purposes. In any case, are you sure that they say that it will cause cancer or that it may do so? I don't think they'd sell it if it really was a known carcinogen.

mick - 3-10-2004 at 07:42

This is from
Prudent Practises in the Laboratory, NAS
LABORATORY CHEMICAL SAFETY SUMMARY: DICHLOROMETHANE

Substance Dichloromethane
(Methylene chloride; aerothene MM)
CAS 75-09-2
Formula CH2Cl2

Physical Properties
Colorless liquid
bp 40 °C, mp -97 °C
Slightly soluble in water (1.32 g/100 mL)
Odor Odor threshold 160 to 230 ppm
Vapor Density 2.93 (air = 1.0)
Vapor Pressure 440 mmHg at 25 °C
Flash Point Noncombustible
Autoignition Temperature 556 °C

Toxicity Data
LD50 oral (rat) 1600 mg/kg
LC50 inhal (rat) 88,000 mg/m3; 30 min
PEL (OSHA) 500 ppm (8 h)
TLV-TWA (ACGIH) 50 ppm

Major Hazards
Low acute toxicity; skin and eye irritant.

Toxicity
Dichloromethane is classified as only slightly toxic by the oral and inhalation routes. Exposure to high concentrations of dichloromethane vapor (>500 ppm for 8 h) can lead to lightheadedness, fatigue, weakness, and nausea. Contact of the compound with the eyes causes painful irritation and can lead to conjunctivitis and corneal injury if not promptly removed by washing. Dichloromethane is a mild skin irritant, and upon prolonged contact (e.g., under the cover of clothing or shoes) can cause burns after 30 to 60 min exposure.
Dichloromethane is not teratogenic at levels up to 4500 ppm or embryotoxic in rats and mice at levels up to 1250 ppm.

Flammability and Explosibility Noncombustible. Dichloromethane vapor concentrated in a confined or poorly ventilated area can be ignited with a high-energy spark, flame, or high-intensity heat source.

Reactivity and Incompatibility Reacts violently with alkali metals, aluminum, magnesium powder, potassium t-butoxide, nitrogen tetroxide, and strong oxidizing agents.

Storage and Handling
This compound should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C.

Accidents
In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If dichloromethane is ingested, obtain medical attention immediately. If large amounts of this compound are inhaled, move the person to fresh air and seek medical attention at once.
In the event of a spill, soak up dichloromethane with a spill pillow or absorbent material, place in an appropriate container, and dispose of properly. Respiratory protection may be necessary in the event of a large spill or release in a confined area.

Disposal
Excess dichloromethane and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines. For more information on disposal procedures, see Chapter 7 of this volume.

I do not think dichloromethane is that bad. In some of the animal tests where possible evidence of cancer is reported the dose per kilogram is higher than what would be recommended for some foods. Considering it has been used on an industrial scale for so long I would have thought that there would be serious evidence of chemical related cancer in workers.

I am sure it has been mentioned else where but the book is so good and free on the net at

http://books.nap.edu/books/0309052297/html/index.html

It gives excellent safety summaries from the chemists point of view for a lot a regular chemicals without trying to scare.

The one table I like is

TABLE 3.2 Probable Lethal Dose for Humans

Toxicity Rating/Animal LD50 (per kg)-
Lethal Dose When Ingested by 70-kg (150-lb) Human
Extremely toxic/ Less than 5 mg-A taste (less than 7 drops)
Highly toxic/ 5 to 50 mg-Between 7 drops and 1 teaspoonful
Moderately toxic/ 50 to 500 mg-Between 1 teaspoonful and 1 ounce
Slightly toxic/ 500 mg to 5 g-Between 1 ounce and 1 pint
Practically nontoxic/ Above 5 g-Above 1 pint

SOURCE: Modified, by permission, from Gosselin et al. (1984). Copyright 1984 by Williams & Wilkins, Baltimore.
That is supposed to be a table, I might have lost the formatting.

I saw some thing this week that suggests formaldehyde/formalin is being re-classified in the EU as a probable human carcenogen after some re-evaluation by some committee. It has been linked to some rare forms of nasal and, I think, throat cancer which is going to be a big problem considering that so many people are/ have been exposed to it from building insulation to pathologists.
mick

Sorry about the table, probable does not make sense.
It is page 42, and is OK with PDF
mick

[Edited on 3-10-2004 by mick]

Mendeleev - 5-10-2004 at 16:02

Will methylene chloride eat through rubber stoppers? I was thinking of distilling it in a standard still joined by rubber stoppers, a la vogel, but I am not sure if DCM will eat through it. Then again I remember reading that toluene dissolves rubber, but vogel says rubber stoppers are fine in an apparatus with boiling toluene.

Quantum - 16-10-2004 at 15:35

As soon as I get mine I will drop some on rubber and report back!

I got some KleanStrip Stripper KS-3 Premium today. I don't know if this makes any diffrence but it was a thick goopy mix. I hope this will not make it a bitch to clean out of my 1000ml flash when I get all the DCM out!

This is my first real distalation so I am exited and worried! Its coming off at 40C and smells of chloroform like the MSDS say it should so it must be DCM. Should I throw out the first fraction and the last fraction or something? Also I have taken a small tube and put one end on the vacume barb and the other in a flask of water. I was thinking it might dissolve vapors or something without causing overpressure.

Anyone know the proper way to store DCM and such? It seems like such a usefull solvent!

This is sooo cool to watch it drip down into the flask. Can't wait till I try reflux!

Quantum

neutrino - 16-10-2004 at 15:45

Quote:

Originally posted by Quantum
Should I throw out the first fraction and the last fraction or something?

That is only done when distilling several substances with close boiling points. The closest thing in your mix should be far off, so you can keep it all.

Crap! Shit!

Quantum - 16-10-2004 at 16:50

When I came out to check on the setup vapor was coming off at 60C! My plan is to redistill what I got.

Is there a good way to chemicaly test for DCM?
Is the paint stripper you guys use all gooey?

Mendeleev - 26-10-2004 at 20:29

No, the paint stripper I used was not goopy, but it was orange made by crown. I am going to try a brand called Jasco's, according to the site >80% DCM. Your distillate should be around 60 C, the stripper has methanol, acetone, toluene, and some sort of polymer shit in it as well, so to get a more complete distillation of DCM you will also get byproducts, but this is okay since you will wash the DCM with water after the distillation. Several water washes will remove the acetone and methanol, but not the toluene, which is why you should keep the distillation below 80 to make sure no toluene gets over.

The Jasco stuff contains only DCM and methanol, so hypothetically no distillation would be necessary, except that polymer shit ruins everything. You still need to distill. Also I performed the distillation with stoppers made from natural rubber, they were fine. DCM does not smell much like chloroform in my opinion, but a lot more like ether, I unstoppered a bottle of DCM at room temperature, causing a venting of gasses and it smelled just like when that happened to my bottle of ether.

[Edited on 27-10-2004 by Mendeleev]

Magpie - 5-9-2005 at 09:05

Chris the Great:

I noticed your post about a successful distillation of dichloromethane from paint thinner in Whimsy. I will be needing some of this most useful solvent. Will you please let us know what brand you of thinner you used and what if any problems you had with the distillation. Thanks.

Tsjerk - 5-9-2005 at 10:41

Little offtopic question, what are the differences between Dichloromethane and Tetrachloromethane? Can they just be subsituted?
I've got some tetra now.

Blind Angel - 5-9-2005 at 14:09

Tetra = 4
Di = 2
so tetrachloromethan is a methane with 4 H substitued by Cl (CCl4) and Dichloromethane is a methane with 2 H substitued by Cl (CH2Cl2)
They can sometime be swapped when used as a solvent, but I don't think that it's that often due to the polarity difference. As a reageant, they can't be substitued.

neutrino - 5-9-2005 at 17:05

I'm assuming that you want to make nitric acid by the methylene chloride extraction? You should know that the more chlorine atoms there are around the central carbon atom, the less useful the chemical for that particular process. I doubt whether CCl4 would work at all.

Also, you should know that carbon tetrachloride is a dangerous carcinogen.

Chris The Great - 5-9-2005 at 22:40

Quote:

Originally posted by Magpie
Chris the Great:

I noticed your post about a successful distillation of dichloromethane from paint thinner in Whimsy. I will be needing some of this most useful solvent. Will you please let us know what brand you of thinner you used and what if any problems you had with the distillation. Thanks.

I used 'Recochem' brand Paint and Varnish Remover. They are a Canadian company, so you might not find the brand in places other than Canada. It has a green and blue label.

There was a goo mixed into it to thicken it, however there was no problems in distillation. I simply heated the stuff in a waterbath with some pottery chips tossed in for boiling chips. I kept the DCM cool with a small amount of salt-ice mix.
The only problem was that now all the goo is a near solid mass in my jar. I haven't tried to get it out but it dissolves in most solvents (gasoline etc) so I think it can just be scooped out. However, it could not be removed from the inside of the metal can the stuff originally came in, so I had to use another metal can (I had an empty acetone can from the same company and used that). I could not get the goo stuff out with any solvents. Keep that in mind, because you'll probably need a new container for your DCM.

One thing I was expecting was more of other chemicals to come over in the distillation, as it listed dichloromethane, methanol and toluene on the back. My end product smells neither of methanol oir toluene, though I think it might have a bit of methanol in it. So, even if other stuff is listed in the ingredients, it's not a problem in my experience.

I ended up with about 3.25L of DCM and 0.5L of goo from roughly 4L of paint and varnish remover. I spilled some DCM on the floor while pouring it into the new container, since it was ackward to pour it out of my 4L pickle jar reciever, and I think that was the main loss.

Magpie - 6-9-2005 at 07:57

Thanks Chris the Great for that detailed description. I was hoping your source did not have the polymer crap in it.

Mendeleev mentioned that Jasco brand is a a likely good source (also has polymer). I am pretty sure I have seen this at Home Depot.

When I was active in sailing I used to go to BC almost every summer - but those days appear to be over. My son and 1st mate has moved to, of all places, NYC.

Chris The Great - 6-9-2005 at 14:36

I think they will all have the polymer in them, it probably keeps it from evaporating instantly and causing people to pass out. Not the kind of bad publicity you want for a product.

However, I suppose the polymer would cause more of a problem in a nice ground-joint glass setup than in my improvised copper condenser and jam jar still I used! Nice big jar mouth means it is easy for me to scoop it out. I would imagine it would be much more problematic if one had to scoop it out through a 24/40 female joint.

Compleat write up on distillation of DCM with pics

Quantum - 8-11-2005 at 21:10

This is my second post in this thread and what a difference there is; more then a year has gone by and I have gone from being a newbee to well not being a newbee

still not exactly an experianced amature chemist but the Sandmeyer reaction was unthinkable for me then and now is in my very near future

In preparation for a large extraction I needed much more DCM then I have now and so spent the day distilling some from the same can of paint thinner I have had all last year.

"Klean-Strip Paint Stipper" was the type used - a goopy polymer mess if there ever was one. I donned the butyl gloves and plop plop plot the mess was poured into my 1 liter RBF 24/40. I made some boiling stones from pottery and dropped them in there and turned on the heat after assembling a standard distillation setup using a liebig condenser with ice water and a 500ml RBF to collect the distillate.

The distillate came off at 40! and slowly rose as the distillation progressed untill it was stopped when the temp got to about 44! This took about 2h 20min in total and mostly involved me watching the distillation and reading General Chemistry by Pauling.

I disconnected the dflask and quickly flushed it with equal volume of cold water. This greatly helped in getting out the gooey junk left over. I advice this for every DCM distillation where polymers are present.

I then cleaned out all the glassware very well and redistilled the DCM and discarded the leftover 30ml or so that was attempting to come over at much higher then 40!

I then refluxed the DCM over anny MgSO4 using a CaCl drying tube on top of the condenser. This was done for about an hour and a half and then the warm DCM was poured into its final resting place - a HDPE bottle - through a filter.

I have read that DCM can offgas through this sort of container so soon I am going to transfer this solvent into a glasswalled home.

Paintstripper is a viable source of dichloromethane given access to proper distillation equipment. Once taken out of the polymer mess DCM is easy to work with generally speaking.

Now to read Flatlanders and browse the forum.

Magpie - 9-11-2005 at 20:13

Quantum that is nice work! Thanks for the complete write-up. I almost missed it with all my screwing around with Waldo over in Whimsy. This write-up will make it easy for me.

I see you are keeping a notebook. I just started doing this too.

Darkblade48 - 9-11-2005 at 21:05

That's a really nice setup, interestingly enough, I was poking around the basement the other day and found a large glass bottle (about 1L) of methylene chloride

Turns out my dad used to use it for melting plastic or something....and now uses it for getting rid of the sticky gunk that labels can sometimes leave behind :O My only comment was to show him a bottle of acetone and told him to use that instead of DCM

Also Quantum: check your inbox, I sent you a PM regarding your reflux setup

Magpie - 13-1-2006 at 16:10

I finally got around to buying a gallon of Jasco "Premium Paint & Epoxy Remover" today for around $25. I placed about 250 mL of this goop in a 500 mL RBF and have been distilling (simple) away for over an hour. It is coming over at 36 to 37C. I expected 40C but this could be due to thermometer miscalibration and/or atmospheric low pressure, I suppose.

This stuff is supposed to be 82.4% DCM and 10% methanol. The MSDS lists the remainder as aliphatic hydrocarbons, which must be the white polymer goop.

My handbooks don't list an azeotrope for methanol/DCM. So I don't know what all that talk was about on earlier posts.

This is very time consuming but will provide a reliable supply of this very valuable solvent. Anytime I don't have anything else to do I can just spend a day distilling off DCM.

Edit: The temperature of the distillate finally did rise to 40C right at the end. Yield: 200 mL clear distillate. Is this a mix of DCM and methanol, pure DCM, or what?

[Edited on 14-1-2006 by Magpie]

[Edited on 14-1-2006 by Magpie]

neutrino - 13-1-2006 at 19:10

Pure DCM? I would bet that this is a mixture and that the low temp was caused by a lack of intermolecular forces between nonpolar DCM and relatively polar MeOH. To be safe, I'd wash it with water, dry, and redistill. That should get you the pure stuff.

Magpie - 13-1-2006 at 22:05

Good suggestions, neutrino.

I'm also going to do a little library research on a possible DCM/methanol azeotrope.

Magpie - 14-1-2006 at 11:51

According to Gmehling's Azeotropic Data DCM does form an azeotrope with methanol: 84%DCM/16%methanol, T=37.8C, P=1atm.

For reference I also noted that it forms one with water:
93.3%DCM/6.7%water, T=38.3C, P=1atm.

So this nicely explains my condensate temperature observations. And yes, I have some cleanup to do.

DCM vs CHCl3 or CCl4

Magpie - 15-1-2006 at 15:08

My 1960's college organic chemistry manual never specified DCM as solvent in any of the procedures although it was mentioned in a list of solvents. Chloroform and carbon tetrachloride were occaisionally used as well as, of course, diethyl ether.

Now, during my recent refresher course the lab manual relies very heavily on the use of DCM, and rarely specifies chloroform, carbon tet, or ether.

Surely this must be due to the lower toxicity of DCM vs chloroform and carbon tet. And compared to ether there is the big advantage DCM's non-flammability.

What I'm wondering is: If lower boiling point and somewhat higher solubility in water aren't an issue, is there any reason that DCM can't be generally substituted for these other chlorinated methanes?

For a specific example take the case of the extraction of phenol from water.

Magpie - 16-1-2006 at 19:50

I took my ~300 mL of crude DCM (from paint stripper) and washed it twice with about 450 mL water. Then I placed several grams of anhydrous Na2SO4 in it and let it set overnight. The next morning I decanted off the DCM and placed a little CaCl2 in it for a few hours. Then I filtered it and redistilled it. Distillate condensing temperature was 38.3 - 39.5 C. Yield = 216 mL.

This temperature puzzles me as the bp for DCM is 40C, and that for the DCM/methanol azeotrope is 37.8C. So I think I'll do some qualitative testing for the presence of alcohol.

Esplosivo - 17-1-2006 at 07:50

Each mole of CaCl2 should sequester 4 moles of methanol (and 3 moles of ethanol) by forming some sort of complexes. The mole ratios should be correct. Therefore you should not have any alcohol in the DCM if you used sufficient CaCl2. If you're unsure try increasing the amount of CaCl2 used.

zooligan - 17-1-2006 at 08:54

Quote:

Just FYI, a product called "Plastisolve" can be had from plastics supply places (there is at least one in every good-sized city) that is mostly all DCM and contains no polymer goo...

-z

Magpie - 17-1-2006 at 18:33

Thanks for the tip Explosivo.

I measured the density with a hydrometer at 12C: it was 1.315. CRC handbook says 1.335 at 15C. Methanol is 0.791 at 20C.

With simplifying assumptions I can calculate the fraction of methanol as follows:

Let X = fraction methanol
0.791X + 1.335(1-X) = 1.315
X = 0.037, or 3.7% methanol

So, I think I'll leave it as is. If I have a need for some extra pure DCM I can always treat it with CaCl2 as suggested.

Plastisolve sounds like it's worth looking into.

[Edited on 18-1-2006 by Magpie]

Plastisolve MSDS says it is pure DCM! Now to just find a source.

[Edited on 18-1-2006 by Magpie]

DeAdFX - 10-12-2006 at 23:48

I have a gallon jug of Methylen chloride/methanol in my garage that has been collecting dust for awhile. When I purchased it the Methylene chloride was colorless and now it has darkened a lot. Should I distill the Methylene chloride with Calcium Chloride or should I add water (and hope that the dark crap is water insoluble) distill, then distill again with CaCl2?

alyks - 7-1-2007 at 01:59

Quantum, what was that thing used to supply water to the condenser?

picketfence - 15-1-2007 at 13:01

Some paint strippers it's easy to distill DCM out of, but recently one brand that used to be used with success with hot water now distills as a white distillate containing DCM and some type of low boiling polymer (I'm guessing).

Any ideas what it could be?

gnitseretni - 28-1-2007 at 12:41

It was asked before by someone but went unanswered..

What were you gonna use the DCM for, nitric acid extraction? If so, was it successful? Maybe write a write-up on that as there's not much information to be found on that process, or at least I can't seem to find it. Maybe someone can point me in the right direction?

Maya - 29-1-2007 at 05:01

<< Quantum, what was that thing used to supply water to the condenser? >>

It's a garden pond water pump for recirculating water

additive in paint-stripper

jamit - 13-9-2011 at 21:47

I did an initial distillation of paint-stripper and acquired about 750ml of dichloromethane. I washed it with about 1.5l of water, then dried it with calcium chloride overnight.

Next day I redistilled in a 1liter rbf. The distillate started to come over at about 38C and quickly rose to 39.5-40C and stayed there for about 1.5hrs. I collected about 600ml.

Then the temperature rose to above 44C and I collected about 100ml. Then the temperature rose again sharply to about 60C where I collected the rest of the distillate, about 40ml.

My question is: should I discard the last two distillate, the ones collected at temperature of 44C and 60C? What is it that I'm collecting at those high temperature?

The msds of my paint stripper only has dichloromethane, methanol, and some polymer stuff.

Any ideas and suggestions? thanks.

drago57 - 13-9-2011 at 22:08

Quote: Originally posted by Magpie

Now, during my recent refresher course the lab manual relies very heavily on the use of DCM, and rarely specifies chloroform, carbon tet, or ether.

Surely this must be due to the lower toxicity of DCM vs chloroform and carbon tet. And compared to ether there is the big advantage DCM's non-flammability.

The lack of modern references to carbon tet. is probably as much to do with it being banned under the Montreal Protocol as anything else.

[Edited on 14-9-2011 by drago57]

purification of otc dichloromethane

jamit - 20-9-2011 at 21:33

Just wanted to share with the sciencemadness community my result in otc dichloromethane and its purification.

I got great result. I did the initial distillation and got about 600ml of dichloromethane between the temperature of 38C to 44C. My source of OTC dichlormethane had only methylene chloride, methanol, and polymer stuff to thicken it and slow the volatility. The initial distillation probably got rid of all the polymer stuff. dischloromethane forms an azeotrope with methanol (93% and 7%) and with water (97.5% and 2.5%).

I did a second distillation and collected only what came over between 39C to 41C. I got rid of what came over initially and the final 100ml in the initial rbf. I collected about 500ml.

Next, I washed the dichloromethane with equal volume of water in a separatory funnel. YOu want to keep the bottom layer. Dichlormethane is heavier than water.

I did a second water wash and allowed it to stand overnight. Next morning I drained the lowered layer into a container and then added 10g of calcium chloride. I let that settle for several hours and then set up for a final distillation. The distillate started to come over between 39C and quickly rose within minutes to 40C and stood there for about 1.5hrs, til almost the end of the distillation.

I was happy with the result: 450ml of pure dichloromethane!

I think its pure, it was coming over at ~40C.

Steve_hi - 21-9-2011 at 08:20

probably a lot cheaper to buy it

[img]http://www.newhorizonsscientific.ca/catalogsearch/result/?q=dichloromethane[/img]

chemicals_2_39.jpg - 8kB

13.49$ for 500ml

simba - 21-9-2011 at 08:24

Quote: Originally posted by Steve_hi

probably a lot cheaper to buy it

[img]http://www.newhorizonsscientific.ca/catalogsearch/result/?q=dichloromethane[/img]

13.49$ for 500ml

I don't know about other countries, but dcm, like many other solvents, is a list II controlled substance and you can't buy decent amounts from supplier without a license.

[Edited on 21-9-2011 by shivas]

simba - 21-9-2011 at 08:34

Quote: Originally posted by jamit

I think its pure, it was coming over at ~40C.

The azeotrope of dcm with methanol is 37.8 ºC and 38.3 ºC with water (according to magpie's post), so boiling temp is not a good thing to be based on in this case.

Takron - 24-9-2011 at 09:43

Quote: Originally posted by neutrino

I don't think they'd sell it if it really was a known carcinogen.

*(cough) Asbestos *(cough)

peach - 26-9-2011 at 07:32

Asbestos is well controlled in the UK, as I'm aware of things it's not allowed in any new installations, only being used for some gaskets on things like centrifuges. Although that may be being phased out as well. I seem to remember most asbestos mines have been closed too.

Benzene is the known carcinogen, it is in List 1 of the IARC tables, which means it is known to positively caused cancer in humans, as opposed to suspected. DCM bottles now have the warning on. I believe that it is a suspected carcinogen due to it showing activity in some animal or cell tests.

Washing paint stripper / grill cleaner first with water also has the benefit of removing any polymers used to thicken the DCM. If not removed first, and they are present, they will stick to the inside of your boiling flask and not come back off with any commonly available solvent.

It will gradually go through plastic. Most common halogenated solvents will at least cause the plastic to swell, or extract things from the plastic; PTFE included. So it's usually stored in glass or metal.

DCM is being phased out of UK paint strippers. The new kind is a thick water based gel and contains no DCM.

One neat thing about DCM is that it's boiling point is only a few degrees over body temperature and it comes in metal cans. You can distil it directly out of the can provided you can make some semi-decent seal on the top and attach a condenser.

Quote:

I think they will all have the polymer in them, it probably keeps it from evaporating instantly and causing people to pass out. Not the kind of bad publicity you want for a product.

It's to make it stick. DCM on it's own is like water and pours off anything that isn't perfectly flat. And it boils off very quickly.

The polymer makes it easier to paint onto door frames and other vertical surfaces.

If you're stripping small parts, the best way to get maximum bang for buck is to paint it on and then wrap the objects up in foil and bags so the solvent has a harder time boiling off, then leave it until it's well blistered.

The new stripper is admittedly much nicer to use. DCM based versions burn like a twat when they make skin contact, they melt brushes and gloves, and go clean through the 'chemically resistant gloves' the DIY shops sell.

The new stuff is like painting on emulsion. No burning, no stench, stays put easily and it entirely washes off with a jet washer; it comes off like a soap.

[Edited on 26-9-2011 by peach]

Stabilizers for Long-Term Storage of Dichloromethane

bfesser - 27-2-2012 at 15:33

By coincidence, I have the next three days off of work and am feeling a bit under the weather. I've decided to raise my spirits by setting up my rotavap to isolate dichloromethane (DCM) from some <a href="http://www.homedepot.com/catalog/pdfImages/ae/ae03e56d-3b90-4169-8968-69657bb63201.pdf">Klean-Strip®</a> I purchased last year. I plan to dilute the product with distilled water before stripping (pun intended) off the DCM. I will use a CO2(s.)/acetone–chilled trap between the rotavap and my precious virgin <a href="http://www.sciencemadness.org/talk/viewthread.php?tid=17008">ULVAC G-10DA(S)</a> rotary vane vacuum pump.

The recovered crude product will be fractionally distilled and dried to remove any remaining alcohols and residual water, as per this and the threads listed at the end of this post. I plan to divide the product into scrupulously cleaned and dried 125 mL amber glass I-Chem™ bottles with PTFE-lined caps. I will leave very little headspace in the bottles, and – as with all my chemicals – I will wrap Parafilm M® around the cap to prevent loosening of the cap and subsequent leakage. I'm aware that the Parafilm M® is "<a href="http://www.parafilm.com/FloraTapeHome.aspx?Menu=2&Prod=Med">not recommended for use with [chlorinated], non-polar aliphatic and aromatic solvents</a>." I do not believe that this will be an issue, however. The bottles of DCM will finally be stored in a refrigerator designated for laboratory chemical storage. The DCM will likely sit undisturbed for up to several years before use.

Immediately upon purchase of the paint stripper last year, I pipetted a small sample of the viscous mixture into one of the bottles I plan to use for storage of the DCM. This was to test the resistance of the PTFE liner to swelling and absorbtion. I haven't yet checked on the cap, but I have not detected any sign of leakage (odor). The MSDS for the product states that it should be used within 6 months of opening, to avoid deterioration of the can.

My questions are these:<ul><li>Do I need to add a stabilizer, as is necessary with trichloromethane?</li><li>I don't remember the exact date I opened the can to take the sample. From the outside, the can appears to be intact. What reactions might the DCM have with the metal of the can in the presence of atmospheric oxygen, moisture, and other constituents of the paint stripper mixture listed in the MSDS?</li><li>Will standard <a href="http://www.carolina.com/product/tubing,+red+vacuum-pressure,+lab+grade,+1-4+in+bore,+1-8+in+wall.do">red rubber vacuum tubing</a> suffice between the rotavap and trap, or do I need to use something else like <a href="http://books.google.com/books?id=mdmTGNrREK8C&pg=PA35&lpg=PA35&dq=tygon+dichloromethane&source=bl&ots=xp7yZMzSMV&sig=oBF 1TFJuI5cTlaq6cHp8Fp_xHI4&hl=en#v=onepage&q=tygon%20dichloromethane&f=false">Tygon®</a>?</li>&l t;/ul>
Related DCM threads:
<a href="http://www.sciencemadness.org/talk/viewthread.php?tid=18824">nasty klean strip</a>
<a href="http://www.sciencemadness.org/talk/viewthread.php?tid=14401">Storage Bottle for Dichloromethane</a>
<a href="http://www.sciencemadness.org/talk/viewthread.php?tid=10306">Dichloromethane Distillation/Azeotropes</a>
<a href="http://www.sciencemadness.org/talk/viewthread.php?tid=7338">Dichloromethane otc product</a>
<a href="http://www.sciencemadness.org/talk/viewthread.php?tid=2363">Dichloromethane from paint remover</a>

[Edited on 2/28/12 by bfesser]

Magic Muzzlet - 27-2-2012 at 16:15

Hey, you are thinking way too hard about this simple procedure.
I don't see the point of purifying it so rigorously anyway if it's being stored for so long, it will need to be purified again if you want it up to the same standards...
I never had problems using it between dist setup and PTFE pump, pumping vapor throug occasionally. Don't worry about it.
Who knows what happened in the can, just distill it!

But wow! Just such an effort to get some CH2Cl2!!

[Edited on 28-2-2012 by Magic Muzzlet]

bfesser - 27-2-2012 at 17:09

I'm using the opportunity to practice with the rotavap. And by virgin, I didn't mean PTFE. I meant that I haven't yet exposed the pump to anything but dry air. As for the red rubber vacuum tubing, it was hard for me to source and was relatively expensive. I'd rather destroy cheap tubing from the hardware store by leaching plasticizers than damage my precious vacuum tubing.

I know I may be over planning things, but that's just my nature. I can't (yet) help being OCD. It's also in my nature to question everything. I believe that inquiry is the whole point of this forum, and of science as a whole. (Please do not drag this thread off topic by discussing the nature of science further.)

I thank you, however, for your advice. I do worry about everything. But, hey! That's what medication is for.

bahamuth - 27-2-2012 at 17:17

Quote: Originally posted by bfesser

As for the red rubber vacuum tubing, it was hard for me to source and was relatively expensive. I'd rather destroy cheap tubing from the hardware store by leaching plasticizers than damage my precious vacuum tubing.

Your red rubber tubing will be crackled and elswhere degraded by light and air before you can kill it with some DCM, if it is anywhere the same stuff I bought from Sigma and VWR. Even think it was Kartell brand. Latex has a expiration date of not more than a year or so.

If it is butyl or similar you don't have to worry about either DCM or air/light for quite some time..

Other than that a rotavap usually can't build extreme vacuums so a regualr thick/stiff walled tube will last you longer and usually is cheaper than the red latex crap.

PS. the ultra vacuum really thick walled Tygon tubes goes real cheap on Ebay once in a while...

Magic Muzzlet - 27-2-2012 at 17:47

Quote: Originally posted by bfesser

I'm using the opportunity to practice with the rotavap.

Yes, I figured that's why you wanted to use it. I understand, I would be more than happy to use my own, if I had one!

Quote:

And by virgin, I didn't mean PTFE. I meant that I haven't yet exposed the pump to anything but dry air. As for the red rubber vacuum tubing, it was hard for me to source and was relatively expensive. I'd rather destroy cheap tubing from the hardware store by leaching plasticizers than damage my precious vacuum tubing.

I know I may be over planning things, but that's just my nature. I can't (yet) help being OCD. It's also in my nature to question everything. I believe that inquiry is the whole point of this forum, and of science as a whole. (Please do not drag this thread off topic by discussing the nature of science further.)

I thank you, however, for your advice. I do worry about everything. But, hey! That's what medication is for.

I worded my post badly, I meant I have used the red vacuum tubing with a PTFE pump, this detail added to emphasize no trap was used and lots of vapor went through. The tubing was fine for a very long time, it was not the CH2Cl2 that I ended up ruining it with.
As for stabilizers, well, there is info in the threads so you can read and decide for yourself if you want to use them or not.
I hope you are worrying about the health effects of CH2Cl2 though, that is worth worrying about.
Have fun with your rotovap!

bfesser - 29-2-2012 at 19:28

Ok, so that didn't work out so well. Apparently the vacuum pump was a little overkill. No sign of condensation or even a reflux ring anywhere in the rotavap condenser, despite the cooling water being barely above freezing. Found the CH2Cl2 condensing in the dry ice/acetone trap--at least something worked as planned. Slowly released vacuum, then shut off the rotavap. This paint stripper is a pain in the ass. The waxy residues clean out of the flask with a few alternating washes of acetone and ethanol followed by a final cleaning of lab detergent and hot water.

Perhaps it'd be worth just purchasing some reagent grade dichloromethane. Or, maybe when it gets warm enough to work outside again, I'll try the distill-from-can method that seems to work so well for everyone else. If only I had a cold finger style condenser for my rotavap.

Glassware porn for your viewing pleasure:
<a href="http://www.adamschittenden.com/Evaporation.php"><img src="http://www.adamschittenden.com/uploads/trotovap/Buchi%20style%20dry%20ice%20condenser.image.jpg"></a>

Sedit - 29-2-2012 at 19:56

Distill from the can is great as a predistillation because all you need to do is solder a copper coil onto a lid and you have the setup you need to do this for a long time but after you get it cleaned up its best to dry it and run it again because it will not come over clean the first time and wax will almost without a doubt carry over somewhat.

Mailinmypocket - 1-3-2012 at 06:38

I have had a few go's at distilling DCM from paint stripper... I eventually got tired of the gunk and hassle and checked on eBay.... Biostain sells DCM in 250/500/1000 ml sizes at very reasonable prices, they ship worldwide and are based in the UK. I receive my orders in great condition everytime. They also sell GAA, Toluene and Xylene I believe but I have never ordered the last two.

http://www.ebay.com/itm/Dichloromethane-99-5-Pure-1-Litre-1L...

thefoxeffect - 30-11-2012 at 16:16

I recently bought a gallon container of Klean Strip Adhesive Remover to distill for the dichloromethane. I did the distillation directly from the metal can that the Klean Strip came in. After a few hours the temperature started to spike so I stopped the distillation. I then redistilled the product once more. I have a few questions concerning the process. In other post and forums, it has been said that methanol and dichloromethane, form an azeotrope, but according to multiple sources I don't think it does,
http://eweb.chemeng.ed.ac.uk/chem_eng/azeotrope_bank.html
It does however from an azeotrope with water, but the % weight is roughly 99.6 methleyne chloride to water, so I am not considering this an issue. So question, am I wrong about dichloromethane and methanol forming an azeotrope? Should I worry about the azetrope between dichloromethane and water, I am wanting decently pure chemical reagents.

Also, I posted some pictures of my setup. I would like to try this again, but to try to achieve maximum efficiency. Would doing a fractional distillation help in this process? The BP of methylene chloride is 39.6 and the BP of methanol is 65. I would like to buy a gallon container of Klean Strip and do a single distillation, straight from the can and into its storage container; that way losing minimal product, and of course having to clean less glassware. Any suggestions or ideas?

One more question, the MSDS of dichloromethane says

"To minimize decomposition, all storage
containers should be galvanized or lined with a phenolic coating. This material may corrode plastic and rubber."

As of now I plan on buying a galvanized paint can at Home Depot to store it, does anyone know of any common storage containers that have a phenolic coating that might be used? Or would I have to order something like that from online?

[Edited on 1-12-2012 by thefoxeffect]

luckybot - 10-2-2013 at 12:17

I have noticed in my own distillate and in the distillate of another users youtube video that there still appears to be a murky whiteness present. I am assuming this might be some of the polymer coming over as an azeotrope. How can this be removed? I have tried placing the DCM in the freezer and this freezes any water present and causes some of the polymer goop to clump together, but it is difficult to filter as the second it starts to warm up the goop disperses back into the DCM.

[Edited on 10-2-2013 by luckybot]

Hexavalent - 10-2-2013 at 12:26

Have you tried filtering over diatomaceous earth, or boiling the DCM (under reflux, of course) for half an hour/a few hours to help increase the particle size of the goop, hopefully causing it to clump together?

Personally, I'd do a rough distillation from the can, and then do a fractional distillation in a glass apparatus to maximise purity: if you're careful, you shouldn't lose too much of your product.

luckybot - 10-2-2013 at 12:48

I just poured in the mess straight out of the KS3 Klean Strip can into a 2L RBF and then pretty heavily diluted it with water to try to thin it out, prolly 50/50 mix. This was stirred and heated on an oil bath using fractional distillation setup. Quite a bit of refluxing was going on and a very large portion of the polymer was clumped together and spinning at the center of the flask. Distillate was then washed 3 times, each time with equal volume of water, this reduced the amount of polymer by quite a bit but it seemed to reach a point where additional washes were no longer helping. After that I placed the DCM in the freezer and returned the next day to find quite a bit of clumped up polymer floating around in it. As far as filtering goes my attempts were made using a medium frit buchner funnel with and without vacuum, while this certainly removed some polymer it looks like there is quite a bit that doesn't clump in the freezer and just makes its way straight through the filter. I will look into acquiring some diatomaceous earth, in the mean time might activated carbon be an option? Thanks.

Update. I went ahead and filtered it through activated carbon, no luck there. Took what I had and redistilled it. Looks even worse after being redistilled. This stuff is a nightmare. I guess I will be searching for another source of DCM.

[Edited on 11-2-2013 by luckybot]

luckybot - 13-2-2013 at 09:17

Okay, another update. I have found some liquid paint stripper that is a mixture of DCM, methanol, toluene, and acetone. Might be creating more problems than I am solving switching to this mixture. It starts out as a clear liquid that you can shake to your hearts content and it remains a clear liquid after shaking. So I fire up the distillation and to my surprise/rage a cloudy white distillate starts to come over, wtf. So I disassemble everything and start cleaning under the assumption that maybe some gunk is left over from previous attempts. This is when I realize that the fiberglass that I use to hold up the column packing is looking awfully nasty. Remove that and use the vigreux without glass beads in it, getting desperate at this point, lol. Finally a clear distillate comes over slightly above the boiling point of DCM and then between DCM and methanols BP. Proceed to water wash and I am back at a murky white, fail once again. So I check what happens when I water wash the raw paint thinner and the same thing happens and it appears to be even more murky white. Any ideas what is going on here? I am using distilled water and I left the murky white gunk over night to see if it would settle out and of course it didn't.

I suppose I will try removing the methanol with CaCl2 next.

[Edited on 13-2-2013 by luckybot]

mr.crow - 13-2-2013 at 12:00

Organic liquids turn white and cloudy when water is dissolved in them. Using CaCl2 is a good idea

Step 1 - Distill crude DCM from paint stripper
Step 2 - Dry with CaCl2 to remove water and methanol. Should turn clear
Step 3 - Distill with clean dry apparatus
Step 4 - Add methanol and put in well sealed dark bottle, etc...

luckybot - 13-2-2013 at 13:24

So perhaps water washing isn't the best way to go? Do you think it will be practical to remove the 16% methanol azeotrope using only CaCl2 or should I still water wash and then hopefully clear up the DCM with CaCl2? I suppose I will try both methods. Thanks for the reply, any ideas on what I can use to hold the column packing up besides fiberglass?

[Edited on 13-2-2013 by luckybot]

mr.crow - 13-2-2013 at 14:02

Copper sponges are supposed to work well for packing material. They can have steel underneath the copper and might rust. Hopefully copper is compatible with DCM vapors.

luckybot - 14-2-2013 at 09:26

Copper is working fine, results are looking a lot better. Fast distill with column packed produces clear distillate with at least 16% methanol probably more. Water wash this and a large chunk of the DCM/Methanol layer goes into the water layer. DCM layer is now murky. Dry using CaCl2, clears up within a couple shakes. Decant into vacuum filter. Perfectly clear DCM. Thanks for the help.

Also just a tip for anyone working with the goop paint stripper, stuff some wet toilet paper into your rbf and swirl it around as hard as you can, cleans it up nicely.

[Edited on 14-2-2013 by luckybot]

Zephyr - 31-8-2013 at 08:50

as noted, the best source of DCM is paint stripper. ive tried several paint removersand had the best results with JASCO (75% YIELD) industrial strenght strippers may have higher concentrations

Zephyr - 31-8-2013 at 08:51

http://www.homedepot.com/catalog/pdfImages/5e/5e960aaf-5ec6-... this is the Jasco paint remover i used

subsecret - 31-8-2013 at 14:44

- Cancer risk of DCM -

Exposure to many hydrocarbons may cause cancer, with cancer risk being (somewhat) proportional to amount of exposure. It seems that exposure to halogenated hydrocarbons has a greater cancer risk. Chances are that cancer won't occur with limited exposure, but still treat DCM with respect. Use your own good judgement when choosing PPE.

Also, please understand that I am not a doctor, and my advice should not be used as medical information.

[Edited on 31-8-2013 by Awesomeness]

sonogashira - 31-8-2013 at 16:38

Chloroform is found in many cough syrups. DCM is less of a cancer risk than chloroform.

bfesser - 31-8-2013 at 17:17

Quote: Originally posted by sonogashira

Chloroform is found in many cough syrups.

I have never heard of this before. Could you give a few examples, please?

subsecret - 31-8-2013 at 17:22

I don't think that it's still used in cough syrups. I've heard that they used to use it for such purposes, but the United States discontinued that. According to the article below, you can still buy chloroform-based cough syrups in the UK.

http://en.wikipedia.org/wiki/Chloroform
Read "Safety."

bfesser - 31-8-2013 at 17:36

Interesting. I learn something new every day. Thank you.

I will return the favor. If you want to link directly to a section in any Wikipedia article, just append it at the end of the URL, like this:
http://en.wikipedia.org/wiki/Chloroform#Safety
(case sensitive and use underscores for spaces)

sonogashira - 31-8-2013 at 18:08

It could be the missing link in smoking related cancers. Everyone just had a cough! I don't know what it's doing there. It's not an active ingredient.

softbeard - 1-9-2013 at 08:52

Back in the 70s and early 80s here in Canada, a lot of cough syrups indeed had chloroform; quite a bit of it too. The theory was that CHCl₃ acted as a mild irritant and helped dislodge phlem by thinning it out. Same reason they used to add ammonium chloride to these syrups.
In my opinion, the whole idea is utter nonsense. Kind of like Vicks Vaporub where mild irritation by the menthol is supposed to help. I think all of these cough syrups are utterly useless. But what are you gonna do in an age where people believe in things like homeopathy.
BTW occasional ingestion of small quantities of chloroform is apparently not as bad as you might think; little is absorbed into the bloodstream from the gastrointestinal track. Still I think it was nuts; like taking strychnine to improve muscle tone.

careysub - 24-3-2015 at 10:24

Deleted as duplicate.

[Edited on 24-3-2015 by careysub]