Metacelsus
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The Electrolytic Chlorination of Ethanol
87.6 ml (1.50 mol) of absolute ethanol were added to 400 ml of 12 M hydrochloric acid. The mixture was electrolyzed in a cell with a stir bar at 5 V
and 1.2 A for 165 hours. The current density was 24 mA/cm2. Platinum electrodes were used for both anode and cathode.
I thought this reaction would produce chloral, which I planned to isolate by fractional distillation. However, I wound up getting chloroform instead
(b.p. 59-65 oC). The yield of chloroform was 68 ml (0.84 mol), density 1.49 +/- 0.02 g/cm3. Interestingly, the reaction mixture
only had one phase. A possible explanation (although I doubt it) could be that the reaction did form chloral, but that it decomposed upon heating.
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leu
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Two German patents on the chlorination of ethanol to produce chloral are in the attached archive  There's threads on producing chloral on SM already  Do you have any references supporting your hypothesis 
[Edited on 5-5-2014 by leu]
Attachment: ChloralPatents.zip (448kB)
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Chemistry is our Covalent Bond
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WGTR
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With platinum electrodes, it's hard to say what exactly you were making. Why not use graphite? That may be better suited for both cathode and
anode in HCl solution. If you use a platinum cathode, it might be necessary to use a divided cell, where the alcohol is being added to the anode
compartment. This is because platinum happens to be very good at reducing things under cathodic conditions. In other words, what is happening at
the anode could be undone at the cathode, with chloroform building up from a side reaction. But I'm not an organic chemist, so your mileage may vary
on that one.
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deltaH
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I'm amazed Chedite that 50cm^2 of platinum electrodes with 5V across it in a 12M HCl solution only drew 1.2A. Any ideas why the low
current?
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kmno4
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Results are interesing, but not very surprising.
Iodoform and bromoform can be obtained in similar way - electrochemical iodination/bromination of ethanol.
Apparently chlorination also may give chloroform.
Explanation of this reaction is not easy, especially that homogenous mixture is obtained. Possibly, formed chloral is oxidized to chloroform during
heating.
I think that results of this experiment are strongly conditions-dependent (concentrations, temperature, current density, amount of electricity... etc)
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Metacelsus
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@DeltaH
I didn't directly measure the voltage across the cell. My power source (a wimpy cellphone charger) may have been outputting less than the rated 5V.
I usually use a rectifier on a variac (this can easily give up to 20A) but I had burned out the rectifier and was waiting for a new one to arrive.
Maybe I will try a graphite cathode to prevent reduction (if I ever do this again).
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deltaH
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Ah okay... that explains it. The devil's in the details 
Yeah I also think graphite should work much better! Will make a mess of carbon powder though, but not an issue really.
[Edited on 6-5-2014 by deltaH]
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Nicodem
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Quote: Originally posted by Cheddite Cheese  | | I thought this reaction would produce chloral, which I planned to isolate by fractional distillation. However, I wound up getting chloroform instead
(b.p. 59-65 oC). The yield of chloroform was 68 ml (0.84 mol), density 1.49 +/- 0.02 g/cm3. Interestingly, the reaction mixture
only had one phase. A possible explanation (although I doubt it) could be that the reaction did form chloral, but that it decomposed upon heating.
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Chloral can decompose to chloroform, but this occurs in basic media. I can't see any mechanism for such a thing occurring in acidic media. You did
distill the reaction mixture directly?
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Metacelsus
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Yes, I did.
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PHILOU Zrealone
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Maybe the chloral is oxydised to trichloroacetic acid and this afterwards lead to decarboxylation...
CCl3-CH=O + O(2-) --> CCl3-CO2H +2 e(-)
CCl3-CO2H --> CCl3-CO2(-) + H(+)
CCl3-CO2(-) --> CCl3-CO2° + 1 e(-)
CCl3-CO2° --> CCl3° + CO2
CCl3° + 1e(-) --> CCl3(-)
CCl3(-) + H(+) --> CHCl3
It is strange that in the mix you don't find the dimeric termination product:
2 CCl3° --> Cl3C-CCl3 (hexachloroethane)
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Metacelsus
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Well, I wasn't looking for it. Anyway, decarboxylation of trichloroacetic acid is plausible, according to this paper:
Attachment: V70N02_097.pdf (601kB)
This file has been downloaded 573 times
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