[nbritton]

What do you get when you react lithium (particularly lithium carbonate, Li2CO3) in a racemic solution alpha lipoic acid? I'm presuming some form of lithium lipoate? Would it precipitate or stay dissolved in solution?

From what I understand sodium lipoate is common, and that dissolves in solution. Would I be correct in anticipating that lithium lipoate would have similar properties to sodium lipoate, given they're both group 1 alkali metals?

Assuming lithium lipoate did not dissolve in solution, would it survive the gastrointestinal track, and could it be more bioavailable than the original, inorganic, lithium carbonate?

[Babcock_Hall]

With respect to the question in your first paragraph, since lithium carbonate is a base, then you should get lithium lipoate.  The solubility of a salt is sometimes dependent upon the identity of the alkali metal.  I would look up the solubilities of some simple carboxylate salts to see whether or not it matters in the case of sodium vs. lithium (I don't think so, but I am not certain).  What is the reason for the question in your third paragraph?

[nbritton]

I tried it and nothing happened. Hasn't lithium's electron already been transferred in the first reaction that produced lithium carbonate? At that point lithium is just an ion (Li+) floating around in solution, so why would it react with the carboxyl group in lipoic acid to form lithium lipoate? Li+ has a full 2s orbital shell, it's 2nd ionization energy is 7298.1 kJ mol-1.

lithium carbonate:

lipoic acid:

I reacted it with elemental lithium, and that worked, but lipoic acid seems to readily polymerize any chance it gets. Furthermore, one time the lithium actually caught on fire, it's a violent reaction; when lipoic acid is in solution, isn't the lithium just merely reacting with the water to form lithium hydroxide? Is there an intermediate lithium compound that I can mix with the lipoic acid that would make the reaction less violent?

One more question, if you reacted DHLA (dihydro-lipoic acid, lipoic acid with the disulfide bond cleaved), would it's two thiol groups also react with elemental lithium to form S-Li+ ionic bonds?

dihydro-lipoic acid:

I can't get SMILES to cooperate, but essentially I'd like three Li+ bonds:

Once the lithium ions disassociate in solution, would the body be able to convert it back into a useable antioxidant form of DHLA or LA? I envision this compound as having psychiatric applications. 1. it delivers lithium, but 2. it would hopefully also deliver LA to aid in the recycling of oxidized glutathione (GSSG) back into reduced glutathione (GSH); oxidative stress is a key factor in several psychiatric disorders, including schizophrenia and mood disorders. Furthermore, NMDA redox site dysfunction is implicated in these disorders, this compound would knock out several birds with one stone.

With respect to the question in your first paragraph, since lithium carbonate is a base, then you should get lithium lipoate.  The solubility of a salt is sometimes dependent upon the identity of the alkali metal.  I would look up the solubilities of some simple carboxylate salts to see whether or not it matters in the case of sodium vs. lithium (I don't think so, but I am not certain).  What is the reason for the question in your third paragraph?

[Babcock_Hall]

The carbonate dianion should remove a proton from the carboxylic acid of lipoic acid, to produce a lithium carboxylate salt and bicarbonate monoanion, HCO₃^1-.  You are correct about lithium:  it is already a cation having lost its electron, relative to lithium metal.

I don't know the pK_a values of reduced lipoic acid (dihydrolipoic acid) offhand, but they are likely to be between 8 and 10.  Therefore, I would suspect that carbonate is a strong enough base to partially remove them.  Lithium hydroxide certainly would remove all three protons.

I strongly urge you not to use lithium metal unless you have training and experience.  It reacts with water to make lithium hydroxide and hydrogen gas.  Because one can buy lithium hydroxide, there is rarely any reason to make one's own.

[Borek]

You obviously have no knowledge nor training required for the chemistry you are trying to do, continuing the discussion would be against forum rules.

Topic locked.