ニトロナフトール類の水銀化反応に関する研究

抄録

Mercuration of 2-nitro-1-naphthol (range of color change, pH 2-6) and 4-nitro-1-naphthol (pH 4.5-7.5) with mercury acetate or oxide at pH 3-10 respectively affords the 4-mercuri (I) and 2-mercuri (II) compounds. Both 2- and 4-vitro-1-naphthols possess such a wide range of color change and the change is so indistinct that the pseudo and aci forms are assumed to be present together over a fairly wide range of pH. They form a fair amount of mercury compounds even at above pH 9. 2, 4-Dinitro-1-naphthol (pH 2-6) afforded a compound assumed to be the 8-mercuri derivative by reaction at pH 3-6 but there was no proof of the substituted position. 1-Nitro-2-naphthol (pH 5.5-7.5) afforded by mercuration at pH 4-7 a mixture of 3, 6-dimercuri, 3-mercuri, and 6-mercuri compounds, as well as the recovery of the unreacted material.
It is concluded from a series of these experiments that the mercuration of nitrophenols and nitronaphthols in a pH range where these compounds take the pseudo form results in the introduction of the mercury ortho or para to the hydroxyl group, while such reaction in the pH range where the compounds take the aci form with the quinoid structure, makes it difficult for the introduction of mercury into the ring. The half-masked mercury still remains as the -HgOCOCH₃ group by recrystallization of the mercury compounds from conc. acetic acid or reprecipitation from sodium hydroxide solution and acetic acid but changes to -HgOH group on drying, and further canges to the anhydride.