05-26-02 14:59
No 314401
While reading some organic chemistry books searching the Hive I came up with an idea of performing this synth. Hope it hasn't been posted before.
Procedure
Prepare a mixture of 13g red phosphorus and 143mL of glacial acetic acid in a 250mL RB flask. Connect a Claisen adapter to the flask; attach a reflux condenser to the side arm, and a thermometer adapter to the straight arm. Then place a gas inlet tube into the thermometer adapter.
Place the apparatus on direct sunlight if possible. The sunlight is very important as the light provides the energy necessary for this reaction to complete. Ordinary light bulb will not work, so this reaction should be performed during summer. With adequate sunlight the reaction will require ~12 hours and in winter it will require two or more days. The longer it takes, the more chlorine will be wasted.
When you have your setup placed on a sunlight start heating the flask on a boiling water bath and pass the current of dry chlorine into the acetic acid. [Note: Chlorine gas prepared from potassium permanganate and HCl can be dried by passing it through conc. H2SO4]. After ~12 hours of bubbling the chlorine gas take a small sample into a test tube and cool it in an ice water bath. It should solidify after rubbing the walls of a test tube with a glass stirring rod. If that happens the reaction is complete and you can set up your flask for a simple distillation. Collect the portion distilling between 160 and 190° C. Cool the distillate in a salt-ice bath and rub the walls with a glass stirring rod. The cristals that form are filtered with suction. The filtrate is then redistilled, this time collecting the portion between 175 and 190° C. The crystals are obtained and filtered as before. The combined portions of crystals are distilled to obtain pure chloroacetic acid. Yield ~100g.
You can also use sulfur as an alternative for red phosphorus as discussed several times here on the Hive.
Life without chemistry would be a mistake.
(Chief Bee)
05-26-02 15:25
No 314412
Is it a synthesis taken directly from that book (if so, which one?), or did you extrapolate from a general outline for the preparation of alpha-halocarboxylic acids (Hell-Vollhard-Zelinsky reaction, right?). I believe the general reaction has been discussed before, as a lot of people wanted to prepare alpha-bromopropionic acid a few moths ago (as that was a very simple step from nitroethane), but I don't think an actual chloroacetic acid synthesis has been posted.
I know chloroacetic acid is a solid at room temperature, but I have forgotten its melting point. Perhaps it is a good idea to not keep the water in the distillation condenser too cold, or it will all crystallize and clog the condenser.
(Hive Addict)
05-26-02 21:09
No 314505
mp. of acetic acid: 16.7 deg celcius
mp. of chloroacetic acid: 59 deg celcius.
(Hive Bee)
05-31-02 19:13
No 316334
The synthesis isn't taken directly from any book. It's true, I read some threads about the preparation of alpha-halocarboxylic acids here on the Hive and that is how I came up with idea for this synth. The only book that was used is J.B.Hendrickson, D.J.Cram, G.S.Hammond, Organic Chemistry, 3rd edition, McGraw-Hill, New York, 1970.
Life without chemistry would be a mistake.
(Chief Bee)
06-04-02 21:09
No 317582
You mean that the synthesis hasn't been tested, it is just an adaption from other texts by you?
(Hive Bee)
06-05-02 10:25
No 317774
SWIM has successfully performed this synthesis, but the only problem is he forgot to calculate the yield. But the synth works.
Life without chemistry would be a mistake.
(Stranger)
06-16-02 09:29
No 321999
This procedure is detailed in the book “The practical methods of organic chemistry” (English translation) by Ludwig Gattermann in 1903. I have adapted the procedure from the book on my website here:
http://roguesci.org/megalomania/synth/sy
Visit my site and forum at http://www.roguesci.org
(Chief Bee)
06-16-02 10:14
No 322007
Mega: Don't you have the different synthetic procedures referenced on your site?
(Wonderful Personality)
11-08-04 14:06
No 540419
From the Ullmann:
Benzalchloride and acetic acid plus tin(II) or tin(IV)chloride yields benzaldehyde and chloroacetic acid.
Patent US3691217
Patents referenced in the Ullmann actually work as I learned.
/ORG
I cant spell, I bad look, the only thing about me is the stuff that I cook......