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My question is about the products formed when phenol reacts with nitrous acid. I googled it and reached this PubChem paper (DOI: 10.1016/S0045-6535(02)00857-3), which states:

It was found that phenol reacts with nitrous acid to produce cyanide ions. Cyanide ion generation is attributed to the conversion of phenol to nitrosophenol through the well-known nitrosation reaction, and decomposition of benzoquinonoxim to form cyanide and aliphatic compound.

Is this correct? If not, then what is the actual reaction?

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    $\begingroup$ The reference is behind a paywall, I assume you bought it or otherwise gained access. Do tell what they did (procedure, conditions) to find said cyanide ions, then we can make an objective evaluation. $\endgroup$
    – Oscar Lanzi
    May 2, 2018 at 13:44
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    $\begingroup$ @Nilay that gets us to the quinoxime,but then what? Assuming the quinoxime forms, it could ultimately release cyanide if either a water molecule or the oxime hydroxyl group attacks adjacent to the oxime carbon. If this occurs, it breaks both the carbocyclic ring and the N-O bond from the oxime. But, is such a reaction plausible? We need access to the paper to know, maybe? $\endgroup$
    – Oscar Lanzi
    May 2, 2018 at 15:28
  • $\begingroup$ @OscarLanzi, I simply typed phenol with nitrous acid on Google and tht was the first link shown by Google.. $\endgroup$
    – Man of Steel
    May 2, 2018 at 16:40
  • $\begingroup$ I found out that this mechanism is only valid in wastewater treatment from all the research papers I gathered and not discussed anything about cyanide formation in general analytic chemistry. It only says that $\ce{NO+}$ is the electrophile in this reaction and nothing about cyanide. $\endgroup$
    – Nilay Ghosh
    May 3, 2018 at 14:33

1 Answer 1

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What the reference says

The reference gives only following figure to support their theory. A weakness of this mechanism is requiring a high energy intermediate like sp2-carbocation.

Cyanide from phenol

An alternative proposal

This alternative avoids high-energy intermediates and thus appears more likely:

enter image description here

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