フェノール類の呈色反応 (第8報)

1,2-ナフトキノン-4-スルホン酸ナトリウムによるフェノール類の呈色反応およびそのレゾルシンの比色定量法への応用

抄録

A color reaction of phenol derivatives by sodium 1, 2-naphthoquinone-4-sulfonate was investigated. Among about 40 kinds of phenols, those substituted by a positive group at a o-position gave much better coloration, while no color or at least only faint color was observed in case of m- or p-substituted one by the same group. Phenols substituted by a negative group gave negative results without exception. As to polyphenols resorcinol alone gave good color and others generally showed brown coloration perhaps due to air oxidation. Similar results were obtained, even when sodium 1, 2-naphthoquinone-4-sulfonate was replaced by 1, 2-naphthoquinone. Then this color reaction was applied for the colorimetric dertermination of resorcinol successfully. Limit of measurement, 20-180μg./ml., and σ=0.846 (n=6). One ml. sample solution (water solution containing 20-180μg./ml., of resorcinol) was taken exactly in 10ml. measurring flask, 1ml. of 0.2% sodium 1, 2-naphthoquinone-4-sulfonate solution and 2.5ml. of pyridine were added and shaken well. After kept standing for 5min. at 15° 1ml. of 0.45N sodium hydroxide solution was added, shaken well and kept standing at the same temperature for 15min. Then water was added to make 10ml. exactly and the absorbance at 680mμ was measured. As a reference solution for the measurement 1ml. of water was treated in the same manner.