Simple Oxidant Monitor

II. The Reaction of Triethanolamine with Iodine

Abstract

Setting up a simple oxidant monitor using KI, the authors found that triethanolamine (TEA) buffer solution depressed the amount of iodine (I₂) liberated from KI. The reaction of TEA with I₂ was thus examined.
The reaction between TEA and I₂ was investigated by product analysis. A fine colorless crystal was obtained upon concentrating the solution of reaction products. The crystal was analyzed by elemental analysis, paper electrophoresis, gas chromatography, infrared spectrometry, and mass spectrometry. The crystalline product was found to be an adduct TEA·HI This colorless crystal is easily soluble in water, and its melting point is 167.5°C. Another product of TEA-I₂ reaction was determined to be HCHO by gas chromatography.
According to the experimental results, TEA and I₂ react irreversibly. The authors propose the following equations for TEA-I₂ reaction.
TEA+ 3I₂+3H₂O=NH₄I+5HI+6HCHO
TEA+HI=TEA·HI
(excess)