5-(p-Dimethylaminophenyl)-2, 4-pentadienal as an Analytical Reagent : A Simple Preparation of the Reagent and Its Application to the Colorimetric Determination of Primary Aromatic Amines

• Published in: Chemical & pharmaceutical bulletin Vol. 30; no. 7; pp. 2467 - 2473
• Main Authors: NAKATSUJI, SHINICHI, NAKANO, RIE, KAWANO, MIE, NAKASHIMA, KENICHIRO, AKIYAMA, SHUZO
• Format: Journal Article
• Language: English
• Published: The Pharmaceutical Society of Japan 01-01-1982
• Subjects: colorimetry of primary aromatic amine
• ISSN: 0009-2363; 1347-5223
• DOI: 10.1248/cpb.30.2467

5-(p-Dimethylaminophenyl)-2, 4-pentadienal (DAPDA) was conveniently prepared from p-dimethylaminobenzaldehyde by using readily available 4-(tert-butylthio)-3-buten-2-one as the chain lengthening agent. It has been shown that DAPDA is a useful reagent for detection and colorimetric determination of many pharmaceuticals (e.g., ethyl p-aminobenzoate (EAB), procaine hydrochloride, sulfisoxazole, sulfamethoxazole, sodium p-aminosalicylate, etc.) containing primary aromatic amino groups. This method is based on the reaction of these amines with DAPDA in the presence of trichloroacetic acid in methanol to form protonated Schiff bases which can be determined spectrophotometrically in the neighborhood of 630 nm. The limit of detection of these aromatic amines was in the range of 0.05-1.0μg/ml in each case. Lambert-Beer's law holds over 0.2-10μg/ml. The results were comparable to those obtained by hitherto reported methods. The method was successfully applied to commercial preparations of primary aromatic amines.