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Mandelic acid interreaction with NaOH/KOH
Hello everyone.
When i worked on mandelic acid essence, I found that it precipitated using NaOH to adjust pH while using KOH didn’t come to the same result. Does anyone knows how it happen?p. s.
- Fomulation
Water to 100%
propanediol (or PEG 400) 20%
mandelic Acid 20%
NaOH 1.966% (or KOH 3.37%)- Adjust pH in order to compliance with regulations of my country.
- Mandelic acid solubility in water：15.87 g/100 mL
- Fomulation
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3 Replies
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The salt form of mandelic acid (the conjugate base sodium mandelate) might not have the same solubility as mandelic acid.
I saw a glimpse on this paper which starts mentioning that even the chirality of the mandelic acid can affect solubility of the salts.
The full explanation is probably some more in-depth chemistry that I don’t know about, are you bringing both to the same exact pH?
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Thank you for your reply.The pH of NaOH edition is similar to KOH one.At the beginning, I think the precipitation of the solution with NaOH is caused by plenty of sodium ions, and that might causes the solubility of mandelic acid decreasing.(Even if more solvent is added, it will still precipitate)May strong electrolyte interfer hydrogen bond forming ?Based on this doubt, I did a test to add a large amount of NaCl to the mandelic acid aqueous solution (Solubility is considered), instead of NaOH. Therefore, the test rules out the effect of pH on the solubility of mandelic acid. However, the precipitation of crystals still formed.Thus, I assume that electrolytes is possible until I finding that KOH edition did not produce crystal precipitation…….haha……..So, I come up to ask and hope someone could give me some advice.Anyway , thank you again.
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Since you compared NaCl to NaOH and still got precipitation, that makes it sound to me like the sodium mandelate is being formed and is not as soluble as the mandelic acid is. Not all salts are very soluble in water
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