Alastair
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Chloroacetic acid alternative ways
Copper(II) chloride is able to chlorinate the alpha position of carbonyl compounds. This reaction is performed in a polar solvent such as
dimethylformamide (DMF), often in the presence of lithium chloride, which accelerates the reaction.
http://www.sciencemadness.org/talk/viewthread.php?tid=2713
Im not quite certain if i want to bubble Cl2 through acetic acid for a few days, because its winter and theres little light outside.
Can this method be adapted? I dont have DMF  maybe i will find some substitute
though. What about other ''gassless'' methods?
[Edited on 11-12-2011 by Alastair]
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AndersHoveland
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I am fairly certain that CuCl2 is not able chlorinate acetic acid like it can chlorinate acetone. The difference is that acetone is a ketone,
whereas acetic acid is a carboxylic acid. A carbonyl, R2C=O, group will behave very differently depending on what other groups it is
attached, whether H, OH, or CH3.
The reason acetone tends to be more reactive is that it can ionize and tautomerize much easier than acetic acid. Extremely acidic conditions,
using a lewis acid such as acetic anhydride or PCl3, are required for acetic acid to tautomerize and thus be able to react in such a way. Sulfur also
allegedly can catalyze the chlorination reaction. Probably it "acts" as a source of SCl2. There are many examples of reactions where two separate
components can act as if they had already reacted together prior to interaction with a third regent, even though they remain uncombined. For example,
in the industrial preparation of sulfur tetrafluoride, a mix of SCl2 and SCl2 similarly "acts" as a source of the unstable SCl4 toward the fluoride
ions.
SCl2 + Cl2 + 4 NaF → SF4 + 4 NaCl
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Alastair
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Hmm, thats an interesting reaction, i thought F was too poor a leaving group for reacting with sulfur.
Im pretty certain chloroacetone with calcium hypochlorite and later strong acid would give chloroacetic, but seems too much of a hassle.
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AndersHoveland
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Quote: Originally posted by Alastair  |
Im pretty certain chloroacetone with calcium hypochlorite and later strong acid would give chloroacetic, but seems too much of a hassle.
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Actually this would be very problematic. The side that already has the chlorine is much more vulnerable to oxidation, since chlorine is an
electron-withdrawing group, and a hydrogen atom on that side will tend to ionize off, leaving a carbon-carbon double bond in a tautomerization.
Cl-CH2-C(=O)-CH2 <==> ClCH=C(-O[-] )-CH2, H[+]
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mr.crow
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Check this out
Halogens can be added to enols and enolates. Acetic wont work since it can't form an enol but acetyl chloride can and will work. The resulting
chloroacetyl chloride can turn acetic acid into more acetyl choride so its like a catalyst.
In acid the halogen makes the carbon less reactive, but base makes it more reactive so you get the haloform reaction instead.
Double, double toil and trouble; Fire burn, and caldron bubble
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kmno4
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| Quote: | | Chloroacetic acid alternative ways |
Amazing alternative: buying it.
Cheap, no more than10-15 euros per kg. Almost in price of dog's shit.
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mr.crow
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This forum is for education and theorizing, not many people make the things they talk about. Maybe one day Alastair will be able to. I'm also all for
buying things if they are available but sometimes its not possible
Double, double toil and trouble; Fire burn, and caldron bubble
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