Myfanwy - 29-1-2010 at 04:14
can you make chloroform, by chlorinating acetone with chlorine to trichloroacetone and then adding sodium hydroxide, to get chloroform?
At first sodium chloroformate and acetic acid is produced,then sodium acetate and chloroform.
what would happen with mono- or dichloroacetone?
what are the byproducts?
and whats the yield?
would be better, than using hypochlorites in the haloform reaction.
CH3COCCl3 + NaOH -> NaCCl3 + CH3COOH -> CHCl3 + CH3COONa
would that reaction work. its the same as the haloform reaction. u just get more trichloroacetone, because u chlorinate it directly. 
ScienceSquirrel - 29-1-2010 at 06:03
Not sure what you are getting at there but acetone will react with a variety of halogenating agents at a range of pH, eg in the presence of acid or
base catalysts, to yield chloro, dichloro and trichloroactone.
All the chloroacetones are powerful lacrymators.
Base catalysed chlorination is preferred as it results in rapid reaction to form trichloroacetone which is then rapidly cleaved as the CCl3- group is
an excellent leaving group. Protonation them results in the formation of chloroform.
Only trace amounts of the chloroacetones are ever present in the reaction mixture.
Picric-A - 29-1-2010 at 06:12
You might as well dissolve acetone in NaOH (aq) then pass Cl2 through that solution.
This will form NaOCl in situe which will perform a haloform reaction with the acetone itself producing chloroform.
DJF90 - 29-1-2010 at 06:25
As far as I am aware, you cannot stop a simple base catalysed Monochlorination can be obtained by acid catalysed chlorination.
The problem with dissolving acetone in NaOH(aq) is that you then have conditions set for the Aldol reaction, leading to condensation and in some cases
even polymerisation. Obviously if you are quick to follow up with chlorination this is a minor problem.
bbartlog - 29-1-2010 at 06:54
Going to the trouble of setting up your gear for Cl2 seems pointless if it's just chloroform you're after. Sodium hypochlorite in solution, plus
acetone, will get you chloroform in one step without the hassle of dealing with chlorine gas. The only caveat I'd add is that if you use OTC bleach
(6%) you end up with quite a large aqueous phase compared to a rather small volume of CHCl3, whereas if you use more concentrated solutions you have
to be wary of the exotherm. But you can always add the acetone in small portions, and cool the reaction, to deal with the latter problem.
As others have already pointed out, there are also problems with doing the reaction in two steps (condensation if you start with the NaOH,
lachrymatory gases if you start with the chlorination).
Myfanwy - 29-1-2010 at 07:14
jes but trichloroacetone and sodium hydroxide will give much higher yields, than the haloform reaction. this is all so dilute. i tried with
hypochlorite and acetone... yield was just shitty.
lachrymatory gasses arent a problem for me. i do it always outside. im not afraid dealing with chlorine, just hold your breath and do this outside and
youre fine. but i breathed some time ago chlorine. very nasty stuff especially in big ammounts.
i would gas 54g Cl2 into 15g Acetone. When the reaction is done i would add the concentrated lye. no polymerisation of acetone and no condenation to
diacetone alcohol.
[Edited on 29-1-2010 by Myfanwy]
[Edited on 29-1-2010 by Myfanwy]
bbartlog - 29-1-2010 at 08:18
Whatever floats your boat. Adding 40g acetone to 2600g of 6% sodium hypochlorite solution, decanting most of the aqueous phase after the reaction is
completed, and then putting the rest into a separatory funnel to drain off the CHCl3 sounds easier to me (and with about $2 for the cost of reagents).
The loss of some of the chloroform in the water is more than made up for by the relative ease of execution and it's hard to get too worked up about
lower yield when the inputs are so cheap.