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Author: Subject: Dichloromethane ?
Wolfram
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[*] posted on 8-11-2003 at 16:05
Dichloromethane ?


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

<!-- bfesser_edit_tag -->[<a href="u2u.php?action=send&username=bfesser">bfesser</a>: subject "Dichloromethan" &rarr; "Dichloromethan<u>e</u>"]

[Edited on 31.8.13 by bfesser]
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[*] posted on 8-11-2003 at 16:18
Rhodium


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]




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[*] posted on 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).
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[*] posted on 23-11-2003 at 10:18


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




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[*] posted on 23-11-2003 at 12:12


Last paint stripper I used had methanol in as well, how do you break the azeotrope
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[*] posted on 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]




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[*] posted on 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?
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[*] posted on 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]




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[*] posted on 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.
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[*] posted on 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]




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[*] posted on 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.
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[*] posted on 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?




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[*] posted on 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?
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[*] posted on 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]




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[*] posted on 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 <i>will</i> cause cancer or that it <i>may</i> do so? I don't think they'd sell it if it really was a known carcinogen.
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[*] posted on 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]
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[*] posted on 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.



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[*] posted on 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




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[*] posted on 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.
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[*] posted on 16-10-2004 at 16:50
Crap! Shit!


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?




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[*] posted on 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]




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[*] posted on 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. ;)




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[*] posted on 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.




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[*] posted on 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.




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[*] posted on 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 CCl<sub>4</sub> would work at all.

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