The color reaction between partially saponified poly(vinyl acetate) and iodine‐iodide in the presence of amylose

The color reaction between partially saponified poly(vinyl acetate), (P‐PVAc), which is dissolvable in water and iodine‐iodide was investigated in the presence of amylose. As the concentration of amylose increases, the absorbance at λmax = 488 nm of the red‐violet complex between P‐PVAc and iodine‐iodide decreases and, on the other hand, the absorbance at λmax = 625 nm of the blue complex between amylose and iodine‐iodide increases. The equation for the relationship between the decrease in the red‐violet complex and the increase in the blue complex was derived. On the basis of this equation, the molar absorption coefficient per iodine molecule at λmax = 625 nm for the blue complex of amylose with iodine‐iodide was found to be 3,68·104 l mol−1 cm−1 at 15°C.