多価アルデヒド類による定量法の研究 (第1報)

Terephthalaldehydeによるo-およびp-Aminophenolの比色定量

抄録

Two moles of o- or p-aminophenol undergoes condensation with 1 mole of terephthalaldehyde to form the Schiff base which has a maximum absorption in ethanol at 380mμ. This absorption makes a bathochromic shift to 445mμ in ethanolic alkali hydroxide solution by formation of a quinoid structure. Aromatic primary amines having, methyl, carboxyl, carboxylic ester, or nitro group, and hydroxyl in meta-position also undergo condensation with terephthalaldehyde but their Schiff bases do not show bathochromic effect due to quinoid structure in an alkaline medium. This fact can be utilized for colorimetric determination of o- and p-aminophenol in the presence of aniline, toluidines, aminobenzoic acids, and procaine by condensation of the phenol in ethanol, basification of the reaction mixture, and colorimetry of the orange-yellow solution. Presence of p-nitroaniline and m-aminophenol gives positive deviation. This determination can be carried out with an error of within ±2%.