Sciencemadness Discussion Board - Diclhloromethane synthesis

Diclhloromethane synthesis

dan.vlad - 5-11-2017 at 05:10

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

Hexavalent - 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]

XeonTheMGPony - 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

markx - 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?

unionised - 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.

DCM synthesis

dan.vlad - 5-11-2017 at 07:48

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

dan.vlad - 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...

dan.vlad - 5-11-2017 at 08:29

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

What about that??
It is achievable?
Thank you

S.C. Wack - 5-11-2017 at 10:33

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

dan.vlad - 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

dan.vlad - 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

battoussai114 - 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?

dan.vlad - 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 ..

dan.vlad - 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?

dan.vlad - 7-11-2017 at 10:18

R 30 refrigerant is DichloroMethane

https://www.researchgate.net/publication/283410683_R30_An_ov...

dan.vlad - 7-11-2017 at 10:24

https://www.phenomenex.com/Compound?id=R30+(Refrigerant)

PirateDocBrown - 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.

Melgar - 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]

aga - 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]

NEMO-Chemistry - 7-11-2017 at 18:54

isnt ethyl acetate considered the more 'green' solvent for many extractions like caffeine?

vmelkon - 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.

clearly_not_atara - 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]

Assured Fish - 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]

dan.vlad - 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..

Mabus - 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.

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.

Melgar - 9-11-2017 at 11:38

That only works at low concentrations though. At high concentrations, you'd get a lot of stuff like tetrachloroethylene.

dan.vlad - 11-11-2017 at 09:06

The teacher,author of many chemistry books, replied to the mail and thanked for that :
"The methods of preparation of compounds given in my book are what I have been reading and teaching for a number of years from differnt books without actually synthesizing them. You may have to go through books on synthetic organic chemistry to know exact synthetic conditions to prepare dichloromethane. "
So..the synthesis exist somewhere..
If somebody know about that..please help
Thank you all for responses and sugestions

clearly_not_atara - 11-11-2017 at 09:42

Quote: Originally posted by dan.vlad

So..the synthesis exist somewhere..
If somebody know about that..please help
Thank you all for responses and sugestions

What's wrong with the route I posted? I don't think you're going to find an "easy" method.
Here's a synthesis of dibromomethane from bromoform, which *may* be an effective replacement -- apparently you're not looking for a solvent:
http://pubs.acs.org/doi/abs/10.1021/es00047a016?journalCode=...

[Edited on 11-11-2017 by clearly_not_atara]

clearly_not_atara - 12-11-2017 at 17:02

Regarding the preparation of methylene halides, I found a paper which describes the bromination of chloroacetic acid to bromochloroacetic acid using aqueous bromine and sodium hypochlorite in 72% yield. Assuming that this can be decarboxylated by heating similar to trichloroacetic acid (see AssuredFish's post on the last page) this gives a reasonably simple preparation of chlorobromomethane.

"62 g (0.83 moles) of sodium hypochlorite was added into 894 mL of alkaline bromine intermediate, containing a total of 262 g (3.26 moles [of Br]) of dissolved bromine in the form of 4.7:1 ratio of Br-:BrO3-. The contents were mixed thoroughly and allowed to react for 24h in a closed 5L round bottom flask, to obtain the 2:1 Br-:BrO3- reagent having 241g of available bromine."

The reaction is essentially 2 Cl⁺ + 2 Br₂ >> 4 Br⁺ + 2 Cl^-, although Br+ and Cl+ are never free ions in solution. Note that the moles of bromine quoted are moles of atomic bromine, Br, not molecular Br2.
The bromination of chloroacetic acid is performed with hydrochloric acid to activate the bromine, in the ratio 1.5g bromine (~3x molar excess) : 5 mmol substrate : 15 mL of 0.9N HCl, rxn for about 3.5 hours or until complete on TLC and quenched with sodium sulfite. The active brominating reagent may be BrCl or its congener HBrCl2, which is reported to form in solutions of bromine (I) in hydrochloric acid. It may be fruitful to experiment with a smaller excess of bromine or other methods of preparing dichlorobromic acid.
Chlorobromomethane boils at 68 C and probably reacts similar to methylene chloride.

Attachment: adimurthy2006.pdf (309kB)
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dan.vlad - 19-11-2017 at 05:18

"Direct conversion of Methane to Methanol, Chloromethane and Dichloromethane at room temperature"

https://www.nature.com/articles/319308a0

If somebody can read this article,please help
Thank you ,all

ninhydric1 - 19-11-2017 at 10:09

Here it is @dan_vlad.

Attachment: methanoltoDCM.pdf (119kB)
This file has been downloaded 547 times

dan.vlad - 19-11-2017 at 22:24

Thank you.
But it's too complicated..

SWIM - 20-12-2017 at 15:52

Ha Ha, this bit of info's been knocking around the back of my mind since ephedrine was OTC in bulk quantities:

Freebase Ephedrine, if left dissolved in chloroform for an extended period, slowly deposits crystals of ephedrine hydrochloride.

Sounds like ephedrine is capable of de-halogenating chlorofrom on an extended time-scale. Don't recall if this required exposure to light or not.

Makes me wonder if ammonia or some alkyl amines might do this, and be re-cycleable to just keep making more and more DCM.

NEMO-Chemistry - 20-12-2017 at 18:35

Quote: Originally posted by SWIM

Ha Ha, this bit of info's been knocking around the back of my mind since ephedrine was OTC in bulk quantities:

Freebase Ephedrine, if left dissolved in chloroform for an extended period, slowly deposits crystals of ephedrine hydrochloride.

Sounds like ephedrine is capable of de-halogenating chlorofrom on an extended time-scale. Don't recall if this required exposure to light or not.

Makes me wonder if ammonia or some alkyl amines might do this, and be re-cycleable to just keep making more and more DCM.

With Light/UV wouldnt Phosgene become an issue? Or would the conditions take care of such side reactions?

I ask because the OP has mentioned various routes as being difficult, that would make me nervous suggesting anything that carried a significant risk, unless of course there is a high chance that Phosgene is not an issue in this situation.

SWIM - 20-12-2017 at 19:11

Quote: Originally posted by NEMO-Chemistry

Quote: Originally posted by SWIM

Don't know anything about the reaction mechanism. In fact, now that I think about it I have no idea how this reaction happens or what the products actually are other than ephedrine hydrochloride.

I read about this in a book about the extraction and purification of alkaloids on a commercial scale. I had never given it much thought but methylene chloride as a product of this reaction really doesn't make much sense...

Maybe it does make phosgene, but I'll be damned if I know where the extra oxygen would come from. Maybe it just forms until the air in the bottle's headspace is used up?

clearly_not_atara - 20-12-2017 at 21:59

Christ with the phosgene. Phosgene is reactive and will never "build up" in any solution that contains any kind of alcohol (incl ephedrine) or which is open to the air. It is hard to make phosgene, you won't do it by accident.

Ephedrine probably slowly reacts with chloroform via Sn2, forming N-dichloromethylephedrine which then cyclizes to 2-chloro-3,4-dimethyl-5-phenyloxazolidine and then maybe eliminate to 3,4-dimethyl-5-phenyl-4H-oxazolinium chloride. I don't expect chloroform to be reduced in this process.

NEMO-Chemistry - 21-12-2017 at 04:24

Quote: Originally posted by clearly_not_atara

Christ with the phosgene. Phosgene is reactive and will never "build up" in any solution that contains any kind of alcohol (incl ephedrine) or which is open to the air. It is hard to make phosgene, you won't do it by accident.

Ephedrine probably slowly reacts with chloroform via Sn2, forming N-dichloromethylephedrine which then cyclizes to 2-chloro-3,4-dimethyl-5-phenyloxazolidine and then maybe eliminate to 3,4-dimethyl-5-phenyl-4H-oxazolinium chloride. I don't expect chloroform to be reduced in this process.

Interesting, i thought there was an inherent danger with Chloroform that didnt have ethanol added. many of the posts on here warn to keep in the dark and add ethanol.

I thought it worth asking, just in case we accidentally 'offed' a member

SWIM - 21-12-2017 at 16:49

Quote: Originally posted by clearly_not_atara

You also don't seem to expect ephedrine hydrochloride to be formed in the reaction you proposed, which makes it hard to see how it could be germane to the deposition of ephedrine hydrochloride in the situation described.
I suspect that even in the early 20th century chemists were capable of telling ephedrine from 3,4-dimethyl-5-phenyl-4H-oxazolinium chloride.

clearly_not_atara - 21-12-2017 at 17:57

One molecule of ephedrine reacts with chloroform to generate two equivalents of hydrogen chloride which precipitates two equivalents of ephedrine hydrochloride. Not that surprising IMO.

NEMO: if you use stabilized chloroform it shouldn't be an issue

[Edited on 22-12-2017 by clearly_not_atara]

Assured Fish - 21-12-2017 at 22:12

I think i may know what is happening with this ephedrine thing.

The secondary amine of the ephedrine may be sufficiently basic enough to dehydrohalogenate the chloroform producing dichlorocarbene.

This would make sense as secondary amines tend to be the most basic of the amines due to the electron donation from the carbons to the nucleophilic amine and the lack of sterric hindrance.
This would leave the dichlorocarbene in the chloroform which could in theory be oxidized by atmospheric oxygen to phosgene, given enough time.

A way to test for this may be to throw some ethylamine or another primary amine into the solution which would result in the rather unpleasant odor of the isocyanide.

AJKOER - 24-12-2017 at 17:36

Quote: Originally posted by dan.vlad

"Direct conversion of Methane to Methanol, Chloromethane and Dichloromethane at room temperature"

https://www.nature.com/articles/319308a0

If somebody can read this article,please help
Thank you ,all

Don't have access to the paper, but suspect this path to CH2Cl2 (and other products) is a variation of the classic photolysis of a mix of Cl2 and CH4, which also uses light to break apart the chlorine gas:

Cl2 + hv --> .Cl + .Cl

However, in the new process, required chlorine gas and perhaps some of the chlorine radical can also be formed by the electrolysis of a chloride, along with the light path above:

Cl- --> .Cl + e- (see https://link.springer.com/article/10.1023/A:1016774717213 )
.Cl + .Cl = Cl2
Cl2 + hv --> .Cl + .Cl

My take on a possible radical reaction chains leading to CH2Cl2:

CH4 + .Cl --> .CH3 + HCl
.CH3 + .Cl --> CH3Cl
CH3Cl + .Cl --> .CH2Cl + HCl
.CH2Cl + .Cl --> CH2Cl2

but CH3Cl and CH2Cl2 are not likely the sole products of the reaction system.

I am basing my comments on the following quote from the abstract of the cited article above:

"The key steps in this process are: (1) electrochemical oxidation of the chloride ion; (2) generation of the chlorine radical under illumination; and (3) formation of the methyl radical by the reaction of methane with the chlorine radical."

[Edited on 25-12-2017 by AJKOER]

madcedar - 23-1-2018 at 01:35

Here is the paper that S.C. Wack was linking/referencing earlier in this thread, Preparation of Methylene Chloride from Chloroform, Ethanol and Zinc (Greene 1879).

Attachment: Preparation of Methylene Chloride (Greene 1879).pdf (213kB)
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dan.vlad - 11-2-2018 at 08:27

Seems interesting, I have to try this reaction
Thank you