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The given answer is (A). At first I thought that it was a simple decarboxylation (due to high heat).

But that does not seem feasible at all as the ring has no electron withdrawing groups which stabilise the carbanion; infact it has electron donating groups which rules out decarboxylation. What else could be a possible mechanism here?

Edit:In the answer posted below could anyone explain how the hydrolysis of triamminobenzene occurs?

  • 1
    $\begingroup$ Redraw the starting material as its imino tautomer and maybe it will become clearer $\endgroup$ – Waylander Jun 29 '20 at 6:37
  • $\begingroup$ It is normal decarboxylation - pericyclic. Carbanion isn't usual intermediate. $\endgroup$ – Mithoron Jun 29 '20 at 15:15

My initial guess for the product was Phloroglucinol, or 1,3,5-trihydroxybenzene1,2

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Belskaya et al.3 says that 1,3,5-triaminobenzene can be formed, but it can eventually be hydrolyzed to Phloroglucinol

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The sources mention decarboxylation as the mechanism. Note that it is the trihydroxylamine 10 that is getting decarboxylated here. The mechanism becomes clearer if you consider the imino tautomers 6 or 7 with the acid group attached and then dehydrate.

In short, Phloroglucinol should be the final product. If that is not one of the options, then 1,3,5-triaminobenzene is the answer you should select.


  1. “PHLOROGLUCINOL.” Organic Syntheses, vol. 9, 1929, p. 74. doi:10.15227/orgsyn.009.0074
  2. Tewari, K.S and Vishnoi, N.K : A textbook of organic chemistry, 4th edition.
  3. Olga B.Belskaya, Valentin P.Talsi, Roman M.Mironenko, Vladimir A.Rodionov, Sergey V.Sysolyatin, Vladimir A.Likholobov, "Transformation pathways of 2,4,6-trinitrobenzoic acid in the aqueous-phase hydrogenation over Pd/C catalyst", Journal of Molecular Catalysis. doi: 10.1016/j.molcata.2016.04.014
  • $\begingroup$ Did you notice it's "side reactions" there? It's not usual at all. Also catalytic hydrogenation environment can influence things. $\endgroup$ – Mithoron Jun 29 '20 at 15:19

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