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Author: Subject: Easy pyridine synth. found in a paper, does it work?
subskune
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[*] posted on 25-6-2017 at 08:14
Easy pyridine synth. found in a paper, does it work?


I am in need of larger amounts of pyridine and therefore the niacin decarboxylization, well known in this forum, is no option. At the bottom of this thread
http://www.sciencemadness.org/talk/viewthread.php?tid=62385#...
someone posted several references for pyridine synthesis. Especially this one
http://gallica.bnf.fr/ark:/12148/bpt6k90810b/f29.image.langE...
woke my interest. Although it is from 1891 it seems to be ok.

The author claims that a mixture of pyridine derivates can be obtained from heating glycerol with ammoniumphosphate and continously destilling of products.

According to the author for 500g of glycerol around 6-8 hours are needed to complete the reaction.

He fractional destilled 2.4kg of the product and obtained around 800g fraction below 120°C which seems to contain mostly pyridine and another 800g fraction at 140-145°C which seems to be of 3-picoline.

This sound amazing since this offers a pretty high yield from very cheap educts. I have glycerol at hand but unfortunately no ammoniumphosphate. Has anyone yet tried this?

Check this paper as well:
http://journals.tubitak.gov.tr/chem/issues/kim-14-38-4/kim-3...

They give a lot of detailed information and point out that many other ammonia salts can be used (diammonium phosphate is said to work best). Additionally this seems to be a one pot synthesis.


[Edited on 25-6-2017 by subskune]
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Aqua-regia
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[*] posted on 25-6-2017 at 11:14


The mentioned latest paper saying: The procedure is not only ionic, but free radical mechanism too . You will obtaining a lot of pyridine isomers and stinky tarry mass. The separation and purification of these will be a big challenge for you. (big suck) But never mind. Try it out, thats the chemistry.


[Edited on 25-6-2017 by Aqua-regia]
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clearly_not_atara
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[*] posted on 25-6-2017 at 11:29


The Chichibabin pyridine synthesis results from a Michael addition of acrolein to acetaldehyde enamine. Maybe you can accomplish this by heating glycerol with acetaldehyde ammonia trimer?

But the "correct" way is probably to make acetoacetate by standard methods and do this:

https://en.m.wikipedia.org/wiki/Hantzsch_pyridine_synthesis

[Edited on 25-6-2017 by clearly_not_atara]
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subskune
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[*] posted on 25-6-2017 at 12:26


I found this in almighty wikipedia:

Quote:

3-Methylpyridine is produced industrially by the reaction of acrolein with ammonia:

2 CH2CHCHO + NH3 → 3-CH3C5H4N + 2 H2O

This reaction also affords substantial amounts of pyridine.


I think this is the major reaction that is takung place, taking the ammonia from the salt which is acid catalyst for the acrolein at the same time. (Correct if I am wrong)

@atara:
since I plan to make around a liter of pyridine the reaction needs to be as cheap and simple as possible. This makes the hantzsch synthesis not economical mostly because of the acetoacetate.

@aqua-regia:
Yep, the first one says that around 2/3 of the product is derivates and waste. However 1/3 are 3-picoline which could be converted to pyridine
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