Nevermore - 10-7-2003 at 01:24
Some time ago a read a few post from Polverone about obtaining chloroacetic acid from hydrolizing trichloroethanol with sulfuric acid, now i wish to
obtain perchloroacetic acid from perchloroethanol, is that possible?
did anyone succeed in following polverone's idea, and what kinda yeld did he get?
Thanks
yields: not so great!
Polverone - 10-7-2003 at 14:13
Industrially, trichloroethylene is hydrolyzed with aqueous H2SO4. I don't recall the exact temperature used, but it's above the BP of TCE,
so I assume it is done under pressure. Since I have no autoclave, I tried to use an atmospheric pressure reflux for extended periods. After 24 hours
of heating, my TCE/water/H2SO4 mixture had a sharp acid scent to it, matching my previous impressions of lab grade chloroacetic acid. Unfortunately,
it had also turned black, there seemed to be some tar stuck in the flask, and I didn't have the necessary distillation apparatus to try purifying
it. I tried again with a more dilute aq. H2SO4 (closer to 50% acid than 75%) in the hopes that I might avoid the Black Gunk, but it still turned black
and this time I didn't even smell chloroacetic acid. I haven't made another attempt since and probably won't until I have the
distillation equipment. This may be months or years (I try to plan ahead) so don't hold your breath waiting for me to refine the procedure.
It is at least possible that the black nastiness came from the H2SO4, as this was a brand of drain opener that was new to me and seemed darker and
less pure than my previous brand. It seemed to turn black in a number of other reactions as well, though I doubt I can blame the tarry bits on it.
Nevermore - 11-7-2003 at 08:34
I will try soon using pure 98% H2SO4, i guess the black you see is just C, but i can be wrong, anyway my acid has never turned black in any reaction,
and is quite clear, just a lil more yellow than water.
I'll just try and see what happens, i do not have distillation equip too so..unless i find a visible layer of chloroacetic i won't be able
to separate!
Nevermore - 15-7-2003 at 13:49
i tried the reaction it yelded up something because the smell, but i was not able to separate it, althought it was severely impure.
Now i am looking for a recipe for chloroacetone, should be easier to make...
ziqquratu - 15-7-2003 at 22:00
For chloro- or bromoacetone, check out http://www.rhodium.ws/chemistry/haloacetone.html