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Author: Subject: separating propionyl chloride and acetonitrile
kangoo
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[*] posted on 27-8-2019 at 18:53
separating propionyl chloride and acetonitrile


Propionyl Chloride can be made by bubbling HCL through propionic acid and acetonitrile. The general scheme comes from:

Comptes Rendus, 121 1155-6 (1895), “Synthesis of amide hydrochlorides and acid chlorides.
Note of Mr. Albert COLSON, presented by Mr. P. Schützenberger.”,
(available in translation on this site: http://www.sciencemadness.org/talk/viewthread.php?tid=7701&a...) and was worked on by Chemplayer in a video on making acetyl chloride from acetic and and acetonitrile, but other acid chlorides (propionyl chloride in this case) can be made as well.

However - propionyl chloride and unreacted acetonitrile have very similar BPs, 80Cand 81C, respectively. (also very similar freezing points. Does anyone have any suggestions on how to separate these two?
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Mush
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[*] posted on 15-3-2020 at 08:23


Acetonitrile has a melting point of -46- (-44)°C, boiling point of 81-82 °C.
propionyl chloride melts at -94 °C , boils at 80 °C.
propionic acid melts at -21 °C , boils at 141 °C
Acetamide.HCl would precipitate out.

CH3COOH + HCl <-> CH3COCl + H2O

If there was access water present (dilute HCl solution+heat ) this reaction would take place:

CH3CN+2H2O HCl = CH3COOH+ NH4Cl

Being anhydrous the below equation is favourable:

CH3CN +H2O =CH3CONH2

So, as long as one keeps the required molar amount of acetonitrile and hydrochloric acid , all acetonitrile should convert to acetamide.HCl consuming the liberated water.
Thus, one would only need to separate propionic acid from propionyl chloride after filtering acetamide.HCl.



[Edited on 15-3-2020 by Mush]
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draculic acid69
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[*] posted on 16-3-2020 at 03:16


What kind of yeild r u getting? chemplayers yeild for acetyl chloride was 7% is the propionyl yeild any better?
Damn autocorrect yeild becomes trips somehow

[Edited on 16-3-2020 by draculic acid69]
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clearly_not_atara
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[*] posted on 16-3-2020 at 05:33


Acetonitrile reacts with HCl with or without carboxylic acids present:

https://www.sciencemadness.org/whisper/viewthread.php?tid=9&...

As such there probably won't be any acetonitrile left after the rxn even if it is used in excess. Also, I thought chemplayer's yield was 30%.

It may pay to use a cosolvent, although I can't think of anything suitable except maybe chloroform.




[Edited on 04-20-1969 by clearly_not_atara]
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UC235
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[*] posted on 16-3-2020 at 07:55


I would just codistill them and use the acetonitrile as reaction solvent. I think the more you try to mess with it, the more likely you are to incur substantial losses of yield.
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draculic acid69
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[*] posted on 16-3-2020 at 08:17


If what your using it for isn't affected by mecn then why not use it as is
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