November 30, 2021, 04:28:20 PM
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Topic: Atractyloside & Atractyloside Potassium Salt - Are these isomers?  (Read 193 times)

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Offline Nolemehc

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Hello, I am looking to purchase Atractyloside however I found there are two names for this compound: Atractyloside and Atractyloside Potassium Salt. However, only the Atractyloside Potassium Salt is commercially available.

Looking at Pubchem, I found they have different CAS registry numbers and different isomeric SMILES.
Atractyloside: https://pubchem.ncbi.nlm.nih.gov/compound/442004
Atractyloside Potassium Salt: https://pubchem.ncbi.nlm.nih.gov/compound/12299879

From this information, I wanted to verify if these two compounds are different and I should NOT purchase the commercially available atractyloside potassium salt?

I also have another question regarding isomeric structure. One structure has a wedge while the other has dashes, does this mean that they are isomers with each other?

Offline Babcock_Hall

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Re: Atractyloside & Atractyloside Potassium Salt - Are these isomers?
« Reply #1 on: November 24, 2021, 03:40:38 PM »
In both of your links, one sees two potassium ions in the structure.  Two potassium ions are also part of both molecular formulae; therefore, they are the same salt form.  The convention of using wedges and dashes in general allows one to differentiate among stereoisomers.  I saw one difference regarding the glycosidic bond to the carbohydrate bearing the two sulfate groups.  They appear to be opposite in configuration in the wedges and dashes drawing and also in the 3D model presented.
« Last Edit: November 24, 2021, 04:06:00 PM by Babcock_Hall »

Offline Nolemehc

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Re: Atractyloside & Atractyloside Potassium Salt - Are these isomers?
« Reply #2 on: November 24, 2021, 03:58:52 PM »
Thank you for the clarification regarding wedges and dashes and stereoisomers.

I attached the 2D structural images below for quick reference.

Both have 2 K+ ions, and everything seems the same except for the wedged/dashed bond connecting to the oxygen as you pointed out.

Offline Borek

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Re: Atractyloside & Atractyloside Potassium Salt - Are these isomers?
« Reply #3 on: November 25, 2021, 03:38:29 AM »
And what do you need it for?
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info, pH-meter.info

Offline mjc123

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Re: Atractyloside & Atractyloside Potassium Salt - Are these isomers?
« Reply #4 on: November 25, 2021, 06:40:32 AM »
If you look at the IUPAC name on the pubchem page, you will see that one is described as 2R and the other as 2S, which refers to the different stereochemistry (wedge-dash) already pointed out. So these are two different compounds, but the difference is NOT that one is a potassium salt and the other isn't - they both are, and you may possibly find either described as a potassium salt or not in different sources. You should ascertain which is the isomer you want. (Hmm, that's an acetal - would they isomerise easily?)

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