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dan.vlad
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[*] posted on 5-11-2017 at 05:10
Diclhloromethane synthesis


Please someone help with Dichloromethane Synthesis by Chloroform
I can't buy only with firm ,and is strictly controled.
In Eu-country the DCM was banned and in paint strippers was replaced
I've seach all over the internet
Thank you
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Hexavalent
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[*] posted on 5-11-2017 at 05:58


As far as I'm aware, there is no simple process that will allow conversion of chloroform to DCM.

If you meant that you want to prepare DCM via a haloform reaction (as we would for chloroform), then this is not possible either. After the addition of two chlorines to the methyl ketone, the remaining alpha-proton is so acidic that the reaction cannot be stopped at this stage (this intermediate reacts much faster than any other electrophile in the reaction mixture). Besides, even if this wasn't a problem, [CHCl2]- isn't a sufficiently good leaving group to allow DCM to be formed.

[Edited on 5-11-2017 by Hexavalent]




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XeonTheMGPony
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[*] posted on 5-11-2017 at 06:06


only way is gas phase reaction in furnace tube under moderate pressure, can't recall if catylest was required or not but sure others will fill in blanks
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[*] posted on 5-11-2017 at 06:59


Simple DCM synthesis is not a viable option, but perhaps chloroform could be used as a replacement....if it is to be used as a generic extraction agent for separating organics from water based systems then quite often it can be used instead of DCM. It will depend of cource on the particular purpose and combination of reagents in question.
Apart from that there are other solvents and solvent mixtures available OTC which can be used for generic extraction puposes: alkene mixtures, heavier ester mixtures, xylene etc.... Perhaps some of these could be a suitable replcament?




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unionised
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[*] posted on 5-11-2017 at 07:35


It ought to be possible to do some sort of exchange reaction between methane and chloroform at high temp in the gas phase.
Not sure it's worth it.
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dan.vlad
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[*] posted on 5-11-2017 at 07:48
DCM synthesis


I have read somewhere about a reduction of Chloroform :
Chloroform + Zn + HCl in Ethanol ..but I can't find anything about
I've spend all the night to search online and in chemical books
I know about synthesis by Methane,but is very complicated,and is needed a real industy investition
Thank you to all
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dan.vlad
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[*] posted on 5-11-2017 at 08:16


DCM can also be prepared by reducing chloroform with hydrochloric acid and zinc metal in ethanol.

CHCl3 + Zn + 2 HCl → CH2Cl2 + ZnCl2 + HCl

http://www.sciencemadness.org/smwiki/index.php/Dichlorometha...
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dan.vlad
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[*] posted on 5-11-2017 at 08:29


http://www.nature.com/nature/journal/v319/n6051/abs/319308a0...

What about that??
It is achievable?
Thank you
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S.C. Wack
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[*] posted on 5-11-2017 at 10:33


https://books.google.com/books?id=pdcBAAAAYAAJ&pg=PA522



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dan.vlad
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[*] posted on 5-11-2017 at 10:53


Quote: Originally posted by S.C. Wack  
https://books.google.com/books?id=pdcBAAAAYAAJ&pg=PA522


Thank you,but what is in that book ?
I don't see the synthesis
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dan.vlad
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[*] posted on 7-11-2017 at 08:22


I've found a gas tank with refrigerated agent DCM
Can I condense the gas to get DCM in liquid form ?
What about the freon disoved in DCM?
I think the freon is tha carrier gase
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battoussai114
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[*] posted on 7-11-2017 at 08:40


Quote: Originally posted by dan.vlad  
I've found a gas tank with refrigerated agent DCM
Can I condense the gas to get DCM in liquid form ?
What about the freon disoved in DCM?
I think the freon is tha carrier gase

Are you sure about that? I've never heard of DCM being used as a refrigerant. Have you checked how much DCM is in the tank?




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dan.vlad
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[*] posted on 7-11-2017 at 08:47


DCM is used as refrigerant from long time
Is no more alowed to use,but I've found ..
My answer is ,how I can condese to get DCM in liquid form?
In DCM is also F ..
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dan.vlad
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[*] posted on 7-11-2017 at 10:05


https://en.wikipedia.org/wiki/Dichlorodifluoromethane

The refrigenrant is known under the name R12
I think can I condese the gas from the cylinder wiht a good condenser coil with negative temperature
How can I get out the Hydrogen Fluoride?
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dan.vlad
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[*] posted on 7-11-2017 at 10:18


R 30 refrigerant is DichloroMethane

https://www.researchgate.net/publication/283410683_R30_An_ov...
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dan.vlad
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[*] posted on 7-11-2017 at 10:24




https://www.phenomenex.com/Compound?id=R30+(Refrigerant)
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PirateDocBrown
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[*] posted on 7-11-2017 at 11:14


I just distill DCM out of paint stripper, then wash out any methanol. Dry with MgSO4, then redistil for purity. I even redistil the MeOH, to get a technical grade stuff good for rinsing glassware.
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[*] posted on 7-11-2017 at 13:43


If you ABSOLUTELY need CH2Cl2 and CHCl3 won't do, then I imagine it's for a reaction and not a solvent, in which case you might want to look into anhydrous cleavage of various forms of polymerized formaldehyde using hydrogen halides. You might find that CH2Br2 suits your need even better than the chloride version?

Ugh. R12 is Freon. You know, that ozone-destroying shit that actually got the world to cooperate enough to enact the Montreal Protocol. Difluorodichloromethane. There's no hydrogen fluoride in there, and if there was, you'd probably kill yourself getting it out. HF is usually obtained by reacting CaF2 with H2SO4, but I highly recommend against attempting that any time soon.

Quote: Originally posted by Hexavalent  
Besides, even if this wasn't a problem, [CHCl2]- isn't a sufficiently good leaving group to allow DCM to be formed.

I'm actually wondering now, if something like the Riemer-Tiemann reaction could be done in the presence of ammonium formate or something else that easily loses hydrogen without a subsequent reaction with the rest of the reactants? Maybe Pd/C under hydrogen pressure, even? It'd be kind of pointless, but sometimes these thought experiments can be fun.

[Edited on 11/7/17 by Melgar]




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[*] posted on 7-11-2017 at 15:26


DCM is one of those things that you either Buy or Don't.

Some chemicals you can make in a reasonable time/with reasonable effort, some you can't.

DCM is one of the 'not worth the trouble' types.

If it's for a solvent, re-think your process and choose another - there are many, some of which Can be made in an amateur environment.

Edit:

Is there Any procedure that you think you Need DCM for, or do you just want to have a bottle on the shelf labelled 'DCM' ? (better in the fridge really).

[Edited on 7-11-2017 by aga]




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[*] posted on 7-11-2017 at 18:54


isnt ethyl acetate considered the more 'green' solvent for many extractions like caffeine?
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[*] posted on 8-11-2017 at 17:25


Quote: Originally posted by dan.vlad  
DCM can also be prepared by reducing chloroform with hydrochloric acid and zinc metal in ethanol.

CHCl3 + Zn + 2 HCl → CH2Cl2 + ZnCl2 + HCl

http://www.sciencemadness.org/smwiki/index.php/Dichlorometha...


That's interesting.
You'll end up with a DCM and Trichloromethane mixture.

DCM = bp = 39.6 °C
Trichloromethane = bp = 56-57 °C

You separate them by distillation.

Also, there was someone who made this stuff with methane and Cl2 + a powerful UV source. As a bonus, you get CCl4.




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[*] posted on 8-11-2017 at 18:32


http://en.wikipedia.org/wiki/Dichloroacetic_acid

According to Wikipedia, chloral reacts with cyanide in the presence of base (calcium carbonate) to produce dichloroacetic acid. Dichloroacetic acid can then probably be decarboxylated to give DCM somehow. I assume this takes place via dehydrohalogenation of the cyanohydrin:

Cyanohydrin formation: Cl3CC(=O)H + HC#N >> Cl3CCH(OH)C#N
Dehydrohalogenation: Cl3CCH(OH)C#N + B- >> BH + Cl- + Cl2C=C(OH)C#N
Keto-enol tautomerism: Cl2C=C(OH) >> Cl2HCC(=O)C#N
Acyl cyanide hydrolyses: Cl2HCC(=O)C#N + H2O >> Cl2HCCOOH + HCN

Cyanide is probably catalytic if I'm right about the mechanism. It's possible that thiamine could act as an alternative catalyst for this reaction because it forms an adduct with aldehydes which is similar to the cyanohydrin. If not, small amounts of cyanide may be prepared from formaldoximes as described here:

https://www.sciencemadness.org/whisper/viewthread.php?tid=23...

EDIT: the reaction is on Orgsyn, I was right, it is catalytic in cyanide:

http://www.orgsyn.org/demo.aspx?prep=CV2P0181

Another compound which has been used as a "nontoxic cyanide" is 1,3-dimethyl-1,2,4-triazolium. I'm not sure how best to synthesize this, however. I think you can make N-phenyltriazole by the rxn of phenylhydrazine with formamide, which is a start....

[Edited on 9-11-2017 by clearly_not_atara]




[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 8-11-2017 at 20:36


As it turns out chemplayer actually investigated the preparation trichloromethane from trichloroacetic acid and just decarboxylated the sodium acetate salt thermally with a yield of 58%.
https://www.youtube.com/watch?v=K0Z_jZd7OeA&spfreload=5

They also investigated the dehalogenation of trichloroacetic acid with zinc.
Curiously they didn't activate the zinc metal before hand.
https://www.youtube.com/watch?v=RDhhJCk2ZbI

If you do intend to try the dehalogenation of chloroform then i would personally suggest activating it first by washing with dillute HCl then water then ether then drying the shit out of it in a desiccator.
activated zinc dust doesn't keep well and will oxidize within a 24 hour span so use it quick or store under an inert atmosphere.

If the dehalogenation fails with activated zinc then i would possibly suspect its a flop.
@dan.vlad I assume you have the necessary equipment to carry out a fractional distillation?

[Edited on 9-11-2017 by Assured Fish]
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dan.vlad
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[*] posted on 8-11-2017 at 20:44


Anyone knows who wrote the page? http://www.sciencemadness.org/smwiki/index.php/Dichlorometha...
At the bottom of the page is a reference,about the DCM synthesis " Organic Chemistry, RL Madan, Tata McGraw-Hill Education, pag. 379"
I think if it's written in the book the synthesis exists
I searched for the book but,I found two of the same author with the same name,but different covers
I've mailed the author " rattanlal.madan@gmail.com " but no response..
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[*] posted on 9-11-2017 at 11:34


I got that reaction from the book when its preview was available through Google books, but later it was removed. I think I might have the book somewhere on my computer, I'll need to look for it. Unfortunately, the reaction in the book didn't have a source, and no mention of any other reaction conditions.
So back then when I had access to Reaxys I did a small search and found a few reactions which involved the reduction of chloroform with Zn.
dichloromet.png - 36kB
Unfortunately I can't access the first 3 articles online, I'm not even sure if some are in digital format.
However, I was able to access the article for the third reaction, and got this interesting bit:
Quote:

Carbon tetrachloride and chloroform undergo rapid reductive dehalogenation in the presence of fine-grained iron metal. With each successive dehalogenation, the reaction proceeds more slowly, and methylene chloride was not significantly degraded over the time scales of our experiments. Relative product distributions do vary with conditions however, so it is possible that circumstances may exist where significant degradation of methylene chloride will occur.

So it would appear that both chloroform and carbon tetrachloride can be rapidly dechlorinated by iron powder in water to dichloromethane, which resists further dechlorination, with little degradation even after a month.
Now I'm curious if this method can be scaled up.




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