nodrog19
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making dichloromethane
is it possible to make dichloromethane from methyl alcohol in the home lab?
how would one go about doing that?
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Nicodem
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It is not possible by using any simple and rational approach. There are however a bunch of irrational approaches though none suitable for a home lab.
Just out of curiosity, why would you want to do that?
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Zinc
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Dichloromethane can be easily bought. There is no point in trying to make it yourself.
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BromicAcid
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| Quote: | | Dichloromethane can be easily bought. There is no point in trying to make it yourself. |
What a simple minded attitude. Although it can be bought, it is hardly available pure and purification procedures can be a pain in the butt depending
on the brand and even if it is locally available. Besides, how many people here have defended manufacturing given chemicals at home simply for the
novelty of making them themselves? Some members here will remind you that thionyl chloride is an industrial chemical and is available (albeit to a
select few). There is something to be learned and enjoyed in making any chemical, please, most members know that a given chemical might be procured
somehow over the counter, but to be honest, it seems a little off topic in a thread titled "Making Dichloromethane".
As for making dichloromethane at home, photochlorination is something that I have always wondered about :
CH<sub>4</sub> + 2Cl<sub>2</sub> ---> CH<sub>2</sub>Cl<sub>2</sub> + 2HCl.
Complications of course arise from finding a chlorine source, finding a methane source (sometimes easy sometimes hard), finding a continuous method of
reaction and finally finding a method to separate the various halocarbons formed. None the less, with some of the more inspiring chemical
manipulations members here have accomplished in recent months I doubt this is beyond the grasp of some of the people here.
[Edited on 6/16/2008 by BromicAcid]
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undead_alchemist
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| Quote: | Originally posted by BromicAcid
| Quote: | | Dichloromethane can be easily bought. There is no point in trying to make it yourself. |
What a simple minded attitude. Although it can be bought, it is hardly available pure and purification procedures can be a pain in the butt depending
on the brand and even if it is locally available. Besides, how many people here have defended manufacturing given chemicals at home simply for the
novelty of making them themselves? Some members here will remind you that thionyl chloride is an industrial chemical and is available (albeit to a
select few). There is something to be learned and enjoyed in making any chemical, please, most members know that a given chemical might be procured
somehow over the counter, but to be honest, it seems a little off topic in a thread titled "Making Dichloromethane".
[Edited on 6/16/2008 by BromicAcid] |
I make many chemicals just for the sake of making them.
It can be both fun an interesting to do so.
Even though I work for lab and chemical supplier, and I can buy what I need.
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S.C. Wack
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I wonder if Nicodem's response has a little to do with the poster and the specific question on the use of methanol, combined with the lack of
feasibility from whatever by whatever.
Reduction of chloroform with Zn and HCl in ethanol:
http://books.google.com/books?id=yAADAAAAIAAJ&pg=PA346
This is identical to the article published in JACS 1, 522 (1879). I would have linked to this instead, but Google has pulled 40 volumes that it used
to have, including this one.
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Nicodem
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Asking why he would want to turn methanol to dichloromethane was so that I could know if he is asking out of ignorance (like believing he needs
dichloromethane, while he obviously does not need it since for caffeine extraction he can use some other suitable solvents - or just buy
dichloromethane or products containing it and distill them) or if he is asking because he likes hardcore challenges (like proving that methanol can be
transformed to dichloromethane in home lab conditions). I can not know the maturity, experience and knowledge of the poster in advance. MeOH could be
turned to methylchloride by one of the numerous methods like passing MeOH+HCl gas over alumina at >300°, photochlorinating the formed MeCl and
fractionally distill the products. Obviously that would be hardcore and irrelevant for Nodrog19.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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BromicAcid
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Sorry for the somewhat heated reply Nicodem, I was just venting a little over some of the other threads where other people suggest to just buy some
chemicals which are no where near avalible OTC. I understand where you were coming from, and that this poster was likely ignorant of the avalibility
of this chemical.
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Nicodem
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Well, actually your somewhat heated reply was to Zinc, while I was replying to S.C. Wack. But nevertheless, you should have noticed by now that in
most cases, especially in beginners' posts, questions like "how can I make X?" are not asked because someone really wants to prepare X, but simply
because he needs it for some experiment or something. For some reason such posters don't know how to express themselves and properly describe their
problem. In such case I think it is beneficial to inform the poster of the OTC availability of X.
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Sauron
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In many places chloroform is now hard or impossible to obtain, same as CCl4, and dichloromethane easy to obtain, so reducing CHCl3 to make DCM under
those circumstances makes little sense.
Making chloromethane (methyl chloride) from methanol is relatively easy; chlorinating it is not particulaly efficient and is hazardous but I bet len1
would be undaunted and so would garage chemist. Whether this is a truly appropriate home lab procedure is a judgement call, one on which I am sure a
spectrum of opinions would emerge.
At least for me, Just Buying It is still easy and possible, in reagent, AR, HPLC grades, or in technical grade by the 200 L drum if I wished.
I think it is easy to understand Nicodem's frustration with some questions of this sort. Perhaps we need a Remedial Beginnings section where people
can be instructed in the fine art of cracking a book to learn elementary principles. Or put up a button that flashed DO NOT PASS GO, GO DIRECTLY TO
FORUM LIBRARY, DO NOT COLLECT $200.
Sic gorgeamus a los subjectatus nunc.
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497
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It actually makes perfect sense because while chloroform may be hard to buy, it is not hard to synthesize. Maybe a little tedious because the yields
aren't great, but it seems like a perfectly valid procedure for a home chemist with more time than money (most of us I think).
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Ritter
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| Quote: | Originally posted by Sauron
In many places chloroform is now hard or impossible to obtain, same as CCl4, and dichloromethane easy to obtain, so reducing CHCl3 to make DCM under
those circumstances makes little sense.
. |
I believe all of the 3 chlorinated solvents mentioned are classified as being carcinogens. Too bad, because dichloromethane (better known as methylene
chloride or DCM) is a wonderful solvent for things that not even acetone will remove from glassware.
I worked in a commercial kilo lab where we were doing a multi-step reaction to convert a natural product diterpene into an aroma chemical via low
temperature ozonolysis in DCM solution. The diterpene was a very viscous liquid that was impossible to remove from glassware without using DCM.
[Edited on 24-6-2008 by Ritter]
Ritter
=============================
\"The production of too many useful things results in too many useless people.\"
Karl Marx
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MagicJigPipe
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DCM is going the way of CCl3(4). Mark my word.
That's why I'm trying to get people to go in on a 55 gallon drum with me. As far as I know I still have that oppurtunity. But certainly not for
long.
"There must be no barriers to freedom of inquiry ... There is no place for dogma in science. The scientist is free, and must be free to ask any
question, to doubt any assertion, to seek for any evidence, to correct any errors. ... We know that the only way to avoid error is to detect it and
that the only way to detect it is to be free to inquire. And we know that as long as men are free to ask what they must, free to say what they think,
free to think what they will, freedom can never be lost, and science can never regress." -J. Robert Oppenheimer
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nodrog19
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What would you reduce it with?
NaNH2 is out of the question.
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blacklung
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Distillation
I haven't done it yet, but considering that DCM is not available in most places (including here), I thought that the best approach would be to
directly distill it from the metal can it is sold in.
You can definitely find dichloromethane in just about any town anyone lives in, but it is definitely going to be impure. Dichloromethane is usually
mixed with other chems that have much higher BPs. I was thinking about just poking a hole in the lid of the can, putting a bent glass tube inside the
hole, and leading the tube to a jar packed with ice. Put the metal can in a hot oil bath, and watch the DCM distill right out of the can.
The novelty of synthing your own DCM would be cool, but this method might be more practical for those who would just like to have an easy source of
DCM...
Thoughts?
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nodrog19
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what is it sold as?
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Tsjerk
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dichloromethane
DCM is sold as paint/sticker remover.
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DJF90
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Last time I went to the DIY store near here I had a look at the paint stripper, and in the cheap "own brand" stuff DCM was the major component (90%+
IIRC  ). And for a 500ml can it only costs about £2.50 (I cant remember exact
figures because its been a while since I last visited). Its amazing what chemicals are available if you take the time to look at labels  Caustic soda (aka sodium hydroxide) is available as 98% pure "pearl" form, and its
not terribly expensive either (~£4 for a kilogram ) But thats for another thread
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JohnWW
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| Quote: | Originally posted by Tsjerk
DCM is sold as paint/sticker remover. |
Yes, but as a solution of the technical-grade compound (likely to
contain some other light chlorinated hydrocarbons such as CCl4, CHCl4, CH3Cl, CH3CCl3) in a heavy hydrocarbon solvent like petroleum jelly, and
usually with small amounts of other ingredients. Separating out the stuff would require distillation, and even then it would be unlikely to be
particularly pure.
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nodrog19
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THanks any way, guys.
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Formatik
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The DCM I've obtained from paint remover was quite impure. I've double distilled paint remover at normal pressure and near the boiling point of
CH2Cl2, and it will still contain a small amount of water that volatilizes (see below) over with the DCM vapors, although mostly it can be mostly
separated by siphoning (2 g DCM solubilizes per 100 mL H2O at 20º). I distilled once with water, so the the gel would not stick to the distillation
equipment. The second time, I removed some water with a dropper and then distilled again.
I checked the density of the final distillate and it was significanly below 1.32 (pure DCM), it was 1.26. Maybe with less water a purer DCM could have
been obtained. Best would be no water, but I'd have to find a container I don't care about. The heating needs only to be done with a warm water bath
anyways.
For dichloromethane synthesis: chloroform is said to be also be made from the electrolysis of KCl in dilute alcohol as in DE 29771 and Frdl. I, 576.
The patent gives a working example only for iodoform. I don't know about chlorine and ethanol in an aqueous medium, I would instead go with acetone
like the patent also mentions next to aldehyde. If that works so simple, it is a very simple way to chloroform, and the KCl can be substituted by
NaCl.
[Edited on 27-6-2008 by Schockwave]
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eirikh1996
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That depends on where
you live. In my home country, Dichloromethane is due to its possible carcinogenity a subject to restrictions and bans
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aga
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Whatever you need, it would be as well to know how to make it from the ground up no ?
Us apes are good with tools.
Oook Oook.
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blogfast25
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Yes. But often it isn't really worth doing or can be very risky. Swings and roundabouts.
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