1956 年 76 巻 6 号 p. 718-721
Mercuration of 2, 4-dinitrophenol (color change in the range of pH 2.0-4.7) and 2, 6-dinitrophenol (-do-, pH 2.0-4.0) with mercury acetate or oxide yields, respectively, 6-mercuri (I) and 4-mercuri (II) compounds when the reaction is carried out at pH 3-7, but no reaction took place at above pH 7. Similar mercuration of 2, 5-dinitrophenol (-do-, pH 4.0-6.0) at around pH 3.7 afforded the 4, 6-dimercuri compound (VI), a mixture of (VI) as well as 4- (VII) and 6-mercuri compounds (VIII) at pH 4.5-6.0, and a small amount of a mixture of (VII) and (VIII) at pH 7.4, recovering majority of the starting material.
The nitrophenol-type compounds are mercurated to some extent even on the alkaline side outside the range of color change. This is assumed to be due, in part, to the fact that the concentration of nitrophenols is far larger than that used as the indicator, so that these compounds are present as the mixture of pseudo and aci forms, and to the salt error of color change range due to the buffer used to adjust the reaction and to the mercuration agent used.
When acetic acid is used for the reaction, a strong acidity (generally below pH 3) inhibits dissociation of mercury acetate and decreases the concentration of the mercuri ion, so that the reaction does not proceed. Therefore, mercuration with mercury acetate or oxide proceeds easily when the medium is around pH 3 to the range of color change of the compound to be mercurated.