Sciencemadness Discussion Board

butanoic acid from sandmeyer rxn

hydride_shift - 17-8-2013 at 04:07

So butanoic acid is a smelly smelly thing which happens to be produced following a GABA -> diazonium intermediate (the specifics of which are well documented).

What interests me is the possibility of salvaging waste butanoic acid from such a reaction for the preparation of low-molecular-weight esters of butyric acid.

Better yet, what conditions would favour the formation of butanoic acid as opposed to the lactone?

kch - 17-8-2013 at 07:18

I would say that since the lactone hydrolyzes to the acid, a little water would be more favorable

turd - 19-8-2013 at 14:12

I think you misunderstood OPs question.

I think OP's talking about this reaction: http://www.erowid.org/archive/rhodium/chemistry/gaba2ghb.htm... (shame on you for not providing the link) and the presumable butyric acid side product. Since it is probably only a minor side product the question is a bit silly.

Or maybe it's me who misunderstood the question - it was not asked in a very coherent way (confusion of lactone and gamma-hydroxy-acid?) had no references and is a classic example of how-not-to-post.

kch - 20-8-2013 at 05:46

Quote: Originally posted by turd  
I think you misunderstood OPs question.

I think OP's talking about this reaction: http://www.erowid.org/archive/rhodium/chemistry/gaba2ghb.htm... (shame on you for not providing the link) and the presumable butyric acid side product. Since it is probably only a minor side product the question is a bit silly.

Or maybe it's me who misunderstood the question - it was not asked in a very coherent way (confusion of lactone and gamma-hydroxy-acid?) had no references and is a classic example of how-not-to-post.


I think I misunderstood the butanoic acid part, but I think I'm right about the lactone to acid

hydride_shift - 21-8-2013 at 05:57

I apologize for any misunderstanding/not referencing said article, and perhaps a poor first thread post. I simply did not want seem to have the wrong intentions.

After attempting said reaction, a long arduous distillation was performed at 120*C, in which (what i presumed was) the majority of lactone in azeotrope was removed. Left in the boiling flask was about 50mL of a VERY stinky solution, which began to precipitate white crystals (presumably unreacted gaba/butaonic acid salts?).
The solution had a pH ~7 and is shown bellow
<img src="http://imageshack.us/scaled/thumb/812/0hf1.jpg">


I was wondering if there was any merit in attempting to salvage Butanoic acid aka butyric acid (CH3CH2CH2-COOH) from said solution for the benign purposes of turning this rancid smelling compound into a sweet smelling one via esterification.

I was considering a simple distillation at ~165*C, or perhaps even drying the precipitate and reacting with a strong acid to see what i got,

Any thoughts on this?

[Edited on 21-8-2013 by hydride_shift]

I Like Dots - 21-8-2013 at 11:48

Try to remove all the GHB/GBL with more water and distillation. Distilling seems the easiest.

Why not an acid base extraction? Butyric acid has a pKa of 4.82