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Author: Subject: Electrochemical production of chloroform
Swinfi2
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smile.gif posted on 24-5-2018 at 00:58
Electrochemical production of chloroform


Soonish I intend to get a power supply and start doing some electrochemistry, to this end I'm wondering about what to do first. I could start with inorganic stuff etc. but as I don't have a lot of chemicals I thought it might be interesting (and useful) to turn some acetone and salt into chloroform.

So my idea is set up a cell with graphite (lantern battery) electrodes, some distilled water and acetone, then saturate it with NaCl maybe even leave a bunch of solid salt at the bottom to keep it saturated as it's consumed.

In theory Cl- should electrolyse to ClO- and this should immediately be consumed by the acetone turning it into chloroform which sinks to the bottom, maybe the cell needs a refluxing condenser as I know both the E and C reactions are exothermic and acetone boils easily.

Can anybody think of any major plot holes that make this an inadvisable experiment to try? If I mess up and run out of acetone in the cell will chlorate oxidise the chloroform? (I like not dying of pulmonary edema and posthumously murdering my entire street) (is an additive a good idea to destroy any nasties like a little NaOH)
Is this a crazy fire/explosion hazard?
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[*] posted on 24-5-2018 at 02:11


If you do this experiment on a small scale (e.g. electrolysis at 1 A for just an hour or so), then I see no real danger. Just use good ventilation or do this outside.

Whether you get chloroform or not is another matter. I doubt you will get a smooth production of chloroform. If you have a solution of NaCl + acetone in water, then do not think that you get immediate production of hypochlorite at the anode. In a cell without acetone, you get Cl2 at the anode and hydroxide (besides H2) at the cathode and only after mixing you get hypochlorite.

If acetone is dissolved as well, then you may have all kinds of interesting reactions:
- oxidation of acetone on anode, instead of oxidation of chloride?
- reaction of Cl2 with acetone, giving chlorinated acetone? (if this occurs, keep in mind that chloroacetone is a potent lachrymator, but if you do this experiment at a small scale for a short time in a well-ventilated room, then I see no serious issue).
- What could happen at the cathode? Can acetone be reduced instead of water?

You may have all kinds of unexpected (side)reactions. I would say, just try this experiment and carefully smell the products you make (do not stick your nose in the beaker, gently waft some of the gases to your head and smell carefully). Also, use a graphite anode, otherwise your experiment will be totally useless.

Please report back on your results if you have done the experiment.




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Swinfi2
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[*] posted on 24-5-2018 at 03:21


looks like I'm lucky, i found this research paper from 1904 ("10.1021/ja01995a005") looks like it's been done before.

They were using platinum electrodes and mentioned about chlorate formation negatively effecting their yields.

Build up of alkaline as the hypochlorite reacts was also a main slowdown factor, so I'll top up the cell with HCl to keep it neutral-ish.

Teeple also suggested using CaCl2 (which I've yet to purify) as a different experiment using NaOH, KOH and Ca(OH)2 and Cl2 gas with acetone Ca(OH)2 was most promising.

It might be a while as I've got about another week left of exams but I'll post back ASAP with what I find.
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[*] posted on 24-5-2018 at 03:30


If I remember correctly there is a section in the libary on the subject.

Found it: http://library.sciencemadness.org/library/books/electrochemi...

[Edited on 24-5-2018 by wg48]
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walruslover69
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[*] posted on 24-5-2018 at 11:25


if you saturate a water and acetone solution with NaCl the water and acetone will separate into 2 different layers.
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[*] posted on 24-5-2018 at 11:40


Why not electrolyse NaCl(aq) with a little NaOH without acetone 1st, then add a drop or 2 every few minutes?
(extra OH- is to react with any Cl2 formed instantly so u only need to stir the soln every few minutes instead of every few seconds)




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[*] posted on 24-5-2018 at 14:50


I tried this once, walruslover69 is right on the money. At a later date I tried using much less NaCl and my conductivity was poor but I had a solution, as the electrolysis progressed it separated into two separate layers anyway. It may have had some chloroform in it but not much.



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[*] posted on 24-5-2018 at 18:50


I am by no means expert in electrochemistry,
but I have noticed that the voltages commonly used (e.g. 5V) are capable of oxidising or reducing most compounds,
so during the electrolysis of mixtures of compounds,
almost any combination of elements/ions/radicals may be formed,
some may be toxic, combustible or explosive.

With my present minimal knowledge I can not predict what may be formed under various conditions but I'm sure plenty of research will be required to be moderately sure of safety.

I am VERY slowly learning a little electrochemistry
- it looks like a very powerful tool but I'm only scratching the surface at the moment.




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[*] posted on 25-5-2018 at 00:33


I actually tried this before. The acetone has a habit of evaporating off, since it's in the top layer. You might consider using isopropanol to start with rather than acetone. It gets oxidized by Cl2 into acetone, and as such, is always at a low enough concentration that it doesn't form a layer. Isopropanol can be salted out too, but not as easily, and probably not if your water/NaCl solution is low-ish. It also keeps the acetone in the vicinity of the anode, which is where the hypochlorite would be forming. I think I worked it out that it's about 20% more energy if you start with isopropanol compared to acetone.

Also, you'll just end up with a mess at the beginning if you run it in a neutral solution, and could easily end up with chloroacetone, which is a potent tear gas. So definitely add some NaOH right at the beginning to get things going.

You could also try adding some mineral oil to it, to prevent evaporation, since you'll need to be running this for a LONG time, and otherwise the chloroform will just evaporate as it forms.




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woelen
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[*] posted on 25-5-2018 at 11:09


I do not think this is a useful way of making chloroform. It is interesting though, but only from an academic/theoretic point of view, trying to understand what happens and what compounds are formed.

So, doing the experiment is not useless or wasteful at all, just manage your expectations well.




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[*] posted on 10-6-2018 at 11:05


For what its worth i always use IPA to make Chloroform, it never seems to get very hot. I do use slightly more IPA (99% stuff) but i think the time saved in chilling down everything and not having boiling off makes up for it. Plus IPA is often much cheaper for me to get.

I would like to hear some thoughts on anodes, A while back i posted a paper that suggested old HDD platters (it wasnt clear if both platters or even if only one side of one platter contained this) that stated the HDD platter was mainly Nickel with some platinum and other rare earth metals in tiny amounts.

As nickel is good in alkali conditions, i wonder if this would make a good anode for this? I do have some HDD platters i will cut them into strips, my feeling is i might need to sandwich two together so the actual nickel platinum side is facing outwards.

Maybe a lowish voltage and current run for a good length of time may be worth while. Anyone got any thoughts before i waste some time?
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[*] posted on 11-6-2018 at 05:10


Quote: Originally posted by Melgar  
I actually tried this before. The acetone has a habit of evaporating off, since it's in the top layer. You might consider using isopropanol to start with rather than acetone. It gets oxidized by Cl2 into acetone, and as such, is always at a low enough concentration that it doesn't form a layer. Isopropanol can be salted out too, but not as easily, and probably not if your water/NaCl solution is low-ish. It also keeps the acetone in the vicinity of the anode, which is where the hypochlorite would be forming. I think I worked it out that it's about 20% more energy if you start with isopropanol compared to acetone.

Also, you'll just end up with a mess at the beginning if you run it in a neutral solution, and could easily end up with chloroacetone, which is a potent tear gas. So definitely add some NaOH right at the beginning to get things going.


I tried this a few years ago (with acetone, not isopropanol). I can confirm the chloroacetone production in neutral solution. Adding NaOH resulted in a bunch of aldol gunk. I should have posted this earlier, but I didn't notice this thread until now.

[Edited on 6-11-2018 by Metacelsus]




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