dotemily
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Propionyl Chloride
Hey hey,
Is it possible to chlorinate Propionic Acid by passing chlorine gas through it to yield Propionyl Chloride?
I decided to try before asking but released I am now unsure what byproducts etc. might have been created.
I carried out the following:
250ml Flask containing 100ml Sodium Hypochlorite Solution connected to a 2 way dripping adapter.
A 250ml dripping flask contained 100ml Hydrochloric Acid which was added dropwise and controlled to keep the flow of chlorine constant but low (1
Bubble every 5-8 seconds)
The Chlorine gas was washed through 2x water gates containing a 10% sodium Hypochlorite solution.
The gas was then fed into the propionic acid using a small hose adapter to try and disperse it best as possible.
The feed from this was then fed into a final water bath.
From this I have observed the following:
Over an hour the Propionic Acid went from a clear white liquid to a pale yellow and finally to a vibrant flourescent yellow.
The water washes both turned a light/pale yellow, the finally water bath stayed fairly clean, sever so slight tint but I observed this as being the
reflection from the new solution.
I now have a flourescent liquid.
Does anyone know what this might contain? Would it in fact contain Propionyl Chloride which can now be seperated or have I missed something obvious
and ended up with something entirely different or even just stained the propionic acid?
Thanks!
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Chemosynthesis
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Sorry, not possible at any normal lab conditions.
You probably have just a mixture of chlorine and acid, one would assume.
What is the source of your propionic acid? This might have some effect on alpha halogenation, but it is essentially impossible for you to have
produced an acyl halide in the manner reported. The mechanism and stability for the latter make it much more difficult than this. Additionally, your
chlorine gas wasn't dried, and so would have introduced water into your reaction.
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Nicodem
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Thread Moved
23-3-2015 at 06:37 |
dotemily
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Quote: Originally posted by Chemosynthesis  | Sorry, not possible at any normal lab conditions.
You probably have just a mixture of chlorine and acid, one would assume.
What is the source of your propionic acid? This might have some effect on alpha halogenation, but it is essentially impossible for you to have
produced an acyl halide in the manner reported. The mechanism and stability for the latter make it much more difficult than this. Additionally, your
chlorine gas wasn't dried, and so would have introduced water into your reaction. |
Thank you for the reply, I do not have or unsure if I can make any of the chlorines needed for the synthesis, Phosphorus Trichloride/ TCCA etc
The only chlorine based reagents availble ar:
Hydrochloric Acid 12%/28% and stronger
Sodium Hypochlorite 5%, 12%, 40%
Calcium Chloride
Ammonium Chloride
Sodium Chloride
I have benzyl alchohol, toluene, benzaldehyde etc.
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woelen
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None of the available reagents does the job. Chlorine probably does react with the acid, but not in the way you want. It can lead to substitution of
H-atoms on the CH3-CH2-chain.
Replacement of the hydroxyl-group on the acidic part of the molecule requires high oxidation state chlorides or non-metal chlorides (e.g. PCl5, PCl3,
NbCl5, WCl6, etc.) or certain acyl chlorides (SOCl2, POCl3, C6H5COCl). Another compound, capable of the wanted reaction is cyanuric chloride (C3N3Cl3,
not to be confused with TCCA, which is C3N3O3Cl3). Such compounds are very strong chlorinating reagents, capable of replacing HO-groups of acids by
Cl-atoms. These reagents are not easy to obtain and this is for a good reason. They are VERY reactive and corrosive and can be used for making really
nasty compounds (e.g. nerve agents, blistering agents).
TCCA is not useful for such chlorinations. There are two kinds of chlorination to be distinguished. One is oxidative/substituting, which replaces
H-atoms, bonded directly to carbon. This requires Cl2, or strong oxidizing compounds, capable of delivering Cl (e.g. TCCA, hypochlorites combined with
acid). The other kind of chlorination is replacement of HO-groups, transforming acid to acyl cloride and transforming alcohols to chlorides. The
latter kind of chlorination requires the kind of reagents, mentioned above.
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gdflp
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If you have access to sulfur, I believe that sulfur monochloride is capable of chlorinating carboxylic acids. A writeup can be found here http://www.sciencemadness.org/talk/viewthread.php?tid=10377
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