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During the Hoffmann Degradation of amides, in the later part of the mechanism, an alkyl isocyanate intermediate is formed which gets hydrolyzed into primary amines. If a simple hydrolysis occurs by addition of $\ce{H2O}$ molecule, then an unstable intermediate, carbamic acid is formed, which decomposes into the primary amine and $\ce{CO2}$. But I cannot find the mechanism anywhere, for the basic hydrolysis of isocyanates, where $\ce{CO3^2-}$ is formed. If the base $\ce{KOH}$ is used, then $\ce{K2CO3}$ forms.

I can simply form a $\ce{CO2}$ molecule first and then react that with $\ce{KOH}$, but I don't know if that's the real mechanism, and I don't want to simply assume the mechanism and move on.

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  • $\begingroup$ I think what you don't want to assume sound just fine. $\endgroup$
    – Mithoron
    Commented Sep 3 at 15:49
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    $\begingroup$ An interesting question might be, how could you experimentally tell if KOH acts on released CO2, only after hydrolysis, or if it participates more actively in the hydrolysis mechanism? $\endgroup$
    – Curt F.
    Commented Sep 3 at 16:58
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    $\begingroup$ Let's be careful about perspective here. No one knows what the real mechanism is. There are only putative or accepted mechanisms that are consistent with known mechanistic experiments and observations. For some possibilities, we do not have experimental evidence and the best guess might be based on similar situations in other reactions that have been studied. Is this one of those situations? I don't know the answer, but someone here might. Or they might not. If that's not a satisfactory viewpoint, well, that's kind of how things are, and it's OK to move on. $\endgroup$
    – Zhe
    Commented Sep 3 at 19:08
  • $\begingroup$ I am only studying in senior high school right now and have no idea about how research in the field of chemistry takes place, but what I believe is that some mechanisms are very probable to be the correct ones, and if they are the most widely accepted ones, then at least an invigilator in an exam will say that I am wrong to follow just any mechanism which sounds fine to me. $\endgroup$
    – Shubham Goel
    Commented Sep 4 at 2:17
  • $\begingroup$ @CurtF. I feel that it does make sense to assume that, if there is a strong base like KOH present, that will affect the substrate much more (or before) the water molecule does. There definitely has to be some attacks by the OH- ion of the base, and then H₂O probably fills us the missing places by attaching H+ ions. "Probably", but I am not sure at all... $\endgroup$
    – Shubham Goel
    Commented Sep 4 at 2:19

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