Talk:Bisulfite
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Structure concern
[edit]"The tautomer on the left has Cs symmetry"
This is not true for the conformation of the ball and stick model shown, but only for two specific O-S-O-H dihedral angles, none of which are shown. — Preceding unsigned comment added by Dreamtheater (talk • contribs) 09:24, 22 July 2013 (UTC)
Aldehyde adduct
[edit]"the bisulfite adducts are charged and so are only soluble in polar solvents" is that right? In the refs given the adduct precipitates out of aqueous solution. Project Osprey (talk) 15:23, 24 February 2023 (UTC)
- Ping User:MasterTriangle12, who added that detail via this edit. DMacks (talk) 17:45, 24 February 2023 (UTC)
- They are α-hydoxyl-sulfonates so the adducts are charged salts and will be more soluble polar solvents. I should maybe change it to "more soluble" though, since the rest of the molecule can sometimes counteract that effect. I looked through a few procedures and where precipitation was mentioned it was mostly due to a saturated solution of bisulfite being used to promote precipitation or adding more salts to "salt out" the adduct. Small bisulfite adducts are actually hygroscopic or even deliquescent, but larger aldehydes might form much less soluble ones and precipitate very easily. A lot of procedures do not precipitate the salt and it remains in the aqueous part of the solution. MasterTriangle12 (talk) 22:23, 24 February 2023 (UTC)
- Common-ion effect? I understand that it is a common lab method for purifying aldehydes but I'm unsure of the particulars. The adduct goes into the aqueous phase, the organic phase (which now contains only impurities) is discarded, then a strong base to break the adduct and solvent-extraction or filtration to get the clean material? It should be possible to explain how it works in general without violating WP:NOTHOWTO. --Project Osprey (talk) 19:39, 25 February 2023 (UTC)
- They are α-hydoxyl-sulfonates so the adducts are charged salts and will be more soluble polar solvents. I should maybe change it to "more soluble" though, since the rest of the molecule can sometimes counteract that effect. I looked through a few procedures and where precipitation was mentioned it was mostly due to a saturated solution of bisulfite being used to promote precipitation or adding more salts to "salt out" the adduct. Small bisulfite adducts are actually hygroscopic or even deliquescent, but larger aldehydes might form much less soluble ones and precipitate very easily. A lot of procedures do not precipitate the salt and it remains in the aqueous part of the solution. MasterTriangle12 (talk) 22:23, 24 February 2023 (UTC)