Melgar
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Nitrile hydrolysis methods to get carboxylic acids
I know the standard ways of creating a carboxylic acid from a nitrile: boiling with NaOH to get sodium salt and heating with H2SO4 to get the acid. I
guess what I'd like to know is, are there other methods that work? and which methods have the best yield?
Would calcium hydroxide work as a base? It probably wouldn't work as well as NaOH, but say I applied 50 psi of pressure and cranked up the heat?
Would it work then? And would I get the double salt or something else? Say I'm trying to get calcium diisopropionate from isopropyl cyanide. Would
the best way be to heat calcium hydroxide with the nitrile (direct, one-pot route) or get the sodium salt or the mixture that comes off of the H2SO4
route and convert that to the double salt of calcium via one of the standard workups?
Theoretically, destructively distilling the calcium salt would give isobutyrone. 
[Edited on 2/17/11 by Melgar]
[Edited on 2/17/11 by Melgar]
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Melgar
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Apparently, everyone seems to agree that somewhat diluted H2SO4 gives the best yields for nitrile hydrolysis. It seems the carboxylic acids form an
organic layer that needs to be further purified. They recommend shaking the organic layer with an aqueous solution of NaOH that will form the sodium
salt and make the organic acids water soluble, then acidifying this solution to get the acid again.
Of course, if the desired product was the double calcium salt, it would stand to reason the organic layer could be shaken with hydrated lime solution
instead, then the aqueous solution would just be evaporated. I seem to recall organic calcium salts being exceptionally water-soluble, though I'm not
sure if that applies to all of them or just some.
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Nicodem
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Thread Moved
19-2-2011 at 01:40 |
Nicodem
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From your posts one gets the impression that you asked before even reading a single experimental procedure for the hydrolysis of nitriles. Therefore,
the best advice I can give you at this stage is to do things in the correct order. That is, first do a literature search on how these hydrolyses are
done and only start looking for alternatives once you gather the understanding of the topic.
Also:
Check the solubility of calcium hydroxide.
Read upon the art of separation methods in chemistry, particularly about extractions, filtrations and distillations.
And use references when opening threads in the Organic chemistry section. For example, using phrases like "everyone seems to agree" without mentioning
who that "everyone" is and where you read about it is not a proper way to start a scientific discussion. If you don't have the skills to perform a
literature search, you can always check the secondary literature first and follow from there, for example, you can first start with experimentals
described in Vogel's, Organicum, Experiments in Organic Chemistry, Systematic Organic Chemistry, or other practical org. chem. books (some
available in SM library). Usually these explains the why's and how's better than the articles do.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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