フェノール類の呈色反応 (第9報)
1,2-ナフトキノン-4-スルホン酸ナトリウムによるo-クレゾールおよびレゾルシンの呈色反応機構について
1965 年 85 巻 1 号 p. 28-32
詳細
1965 年 85 巻 1 号 p. 28-32
A mechanism of color reaction of sodium 1, 2-naphthoquinone-4-sulfonate with either o-cresol or resorcinol was investigated by isolating reaction products.
Reaction of sodium 1, 2-naphthoquinone-4-sulfonate with either o-cresol or resorcinol, in the presence of sodium hydroxide and pyridine, produced 3-methyl-3′-hydroxy-5′, 6′-benzo-4, 4′-diphenoquinone (II) from o-cresol and 2, 3′-dihydroxy-5′, 6′-benzo-4, 4′-diphenoquinone (III) from resorcinol, respectively. The absorption curves of II and III in alkaline solution are nearly coincident with that of the colored solution produced by 1, 2-naphthoquinone-4-sulfonate and either o-cresol or resorcinol. Therefore, the reaction mechanism of the coloration is considered that sodium 1, 2-naphthoquinone-4-sulfonate attacked at p-position of phenol initially as an electrophilic reagent to form addition product of 1, 2-naphthoquinone-4-sulfonate tentatively, and then desulfonation afforded either II or III, which showed coloration in alkali by dissociation.
