(Brain)2NH
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Benzene ring with three phenoxides
hi all,
I wondered what would be the name of the following structure :
And can this be made like simple mono-phenoxides, (Phenol + NaOH) ?
I mean do you think all this phenol groups will change to Pheoxides only by NaOH ?
TnX
RC(O)NH2 -----------> RNH2 !
Hoffman Rearrangement
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Nicodem
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Just for your information, the thread tittle makes no sense. Your depiction shows the enolate form of the phloroglucinol trisodium salt. That is no
"benzene ring with three phenoxides".
According to ChemSketch, its name is trisodium benzene-1,3,5-triolate. (you could have checked that yourself)
| Quote: | | And can this be made like simple mono-phenoxides, (Phenol + NaOH) ? |
Just like with all the salts, its existence depends on the pKa values, crystal lattice stability and in this particular case also the isomeric
stability. Some salts simply do not crystallize, some only exist in the amorphous form, same are stable only by coordination with additional ligands
(for example, only as hydrates), etc.
The trianion of phloroglucinol was found to be predominantly in the enolate form in aqueous solutions (unlike the dianion which exists as the keto
anion): see Zeitschrift für Naturforschung B 1993, 48, 478-482 (abstract can be found here). However, this does not necessarily mean that the same isomer is the most stable also in the solid state. Like is always the case, if you
want to know if one compound exists, you need to do a literature search.
| Quote: | | I mean do you think all this phenol groups will change to Pheoxides only by NaOH ? |
The predicted pKa3 of phloroglucinol is 11.8 (ChemAxon prediction), so that NaOH should deprotonate it nearly completely up to the trianion. However, dissolving phloroglucinol in three
equivalents of aq. NaOH would not necessarily precipitate the desired salt. Most likely it would only give its aqueous solution. Obtaining the product
from the solution might or might not be trivial. Rotavaping it might yield an amorphous solid or the product might crystallize as a stable hydrate.
Short answer: check the literature.
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