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Communication | Regular issue | Vol 4, No. 7, 1976, pp.1257-1262
Published online, 1st January, 1970
DOI: 10.3987/R-1976-07-1257
The Mechanism in the Colorimetry of Caffeine and Theobromine by Hypochlorous Acid-Pyridine Method

Kazuo Kigasawa, Kazumi Ohkubo, Toshitaka Kohagisawa, Hiroaki Shimizu, Setsu Saitoh, and Tetsuji Kametani*

*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan


Caffeine (1) and theobromine (2) reacted with pyridine in the presence of hypochlorous acid to give 8-(N-pyridinium)xanthine salts, which were characterised as the triiodides (3 and 5) and monoiodides (4 and 6). Treatment of 8-(N-pyridinium)caffeine iodide (3) with sodium hydroxide afforded sodium 5-(caffeine-8-yl)imino-1,3-pentadienoxide (7). This experiment made clear the mechanism in the colorimetry of caffeine by hypochlorous acid-pyridine method.