The Pore Size of Keratin

Abstract

The extent to which wool may be iodinated with alcoholic solutions of iodine at 22.2°C. has been examined as a function of the size of the alcohol molecule. With a solution of iodine in methanol or ethanol, the limiting amount of combined iodine is approximately what would be expected if the whole of the tyrosine were converted into 3 : 5-di-iodotyro sine. When. however, a solution of iodine in n-propanol is used, the reaction proceeds more slowly and comes to an end when the amount of combined iodine is less than half the theoretical value. This result, and the fact that solutions of iodine in n-butanol and n-pentanol give so small an extent of iodination as to suggest that reaction is restricted to the surface of the fibers, confirm an earlier deduction from the elastic properties of wool fibers in alcohols of increasing molecular weight [6] that the fine structure of wool is inaccessible to molecules larger than those of n-propanol.