Should sodium lipoate react with ascorbic acid?

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Discussion Overview

The discussion revolves around the reaction between sodium lipoate and ascorbic acid, particularly focusing on the formation of a yellow insoluble substance and the implications of potential impurities in the reactants. Participants explore the chemical interactions and products resulting from these compounds, as well as the characteristics of the observed substances.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes mixing R-Alpha lipoic acid with sodium bicarbonate to create sodium lipoate and questions whether it should react with ascorbic acid.
  • Another participant suggests that the yellow substance formed could be sulfur or a sulfur compound, given that sodium lipoate contains sulfur.
  • There is uncertainty about the specific products of the reaction between ascorbic acid and sodium lipoate, with participants attempting to clarify the chemical equation.
  • Some participants inquire about observable signs of reaction, such as gas production, to better understand the reaction dynamics.
  • A participant notes that the yellow substance appears even without the addition of ascorbic acid, leading to speculation about the purity of the alpha-lipoic acid used.
  • Another participant proposes that the gooey substance might be a result of polymerization of lipoic acid.

Areas of Agreement / Disagreement

Participants express varying opinions on the nature of the yellow substance and the reactions involved. There is no consensus on the exact products or the implications of the observed reactions, indicating ongoing uncertainty and exploration of the topic.

Contextual Notes

Participants acknowledge the potential for impurities in the alpha-lipoic acid and the complexity of the reactions involved, but do not resolve these issues. The discussion includes references to chemical properties and behaviors without definitive conclusions.

bassamnfs
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Hi,
I've bought R-Alpha lipoic acid powder (not sure about its purity). So I mixed 500mg of ALA with 250mg sodium bicarbonate to get sodium lipoate, 30 minutes later (when the reaction is over) I added some 250mg of pure ascorbic acid to the final mixture and some small amount of insoluble sulfuric color goo formed. my question: Is this an impurity in ALA ? In other words: should Sodium lipoate react with ascorbic acid in anyway? if it reacts what are the reaction's products?

Thanks in advance
 
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I'm not sure what exactly the reactants would be, but the sulfuric color goo is likely sulfur itself or a sulfur compound, since Sodium Lipoate contains sulfur.
Also, just to clarify, would this be your reaction...
C6H8O6 + NaC8H13O2S2
?
 
Thanks for your replay.
Yes exactly, what would C6H8O6 + NaC8H13O2S2 ----> ?
 
bassamnfs said:
Thanks for your replay.
Yes exactly, what would C6H8O6 + NaC8H13O2S2 ----> ?
I can't tell you off the top of my head. Unless anyone else knows, maybe you could try to figure it out intuitively. Was there any bubbling in the reaction to indicate a gas? Or any other visible products besides the sulfur (or sulfur compound)?
 
There is a reaction after adding ascorbic acid because it produces the yellow insurable substance I mentioned earlier
 
bassamnfs said:
There is a reaction after adding ascorbic acid because it produces the yellow insurable substance I mentioned earlier
Yeah I saw that part, but could you tell if their was any bubbling at the surface? That would indicate that a gas (such as CO2 or H2) was produced as another product.
 
No, there was no gas or any indication of a reaction
 
bassamnfs said:
No, there was no gas or any indication of a reaction
Then the best advice I personally can give you is that you can perform tests on the other products and attempt to match their properties with properties of potential products that could be produced (i.e. Density, freezing point). This might take a while but I can't think of any other way. Even so, it might not work if the products are in a mixture. Worth a try though if you have some spare time!
 
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Could you be re-protonating the lipoate with the ascorbic acid and precipitating out the fatty acid? I don't know the pKa's of the species involved, but organic acids tend not to be water soluble when they're not dissociated.
 
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  • #10
Thanks for the reply.
I retried the reaction again to find out that the gooey substance will be produced from the very first reaction ( ALA + Sodium bicarbonate), means without even adding ascorbic acid later. I get the same results ( waiting time for the reaction to complete 30 minutes, before not exactly 30 minutes ).
I took this gooey substance and put it on the stove, it melted to a brownish liquid then started to smoke, by smell it's similar to sulfur but not sure... anyway, I think this powder of alpha-lipoic acid is impure...
 
  • #12
Ygggdrasil, appreciate your help. thanks
 

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