Optimum reaction conditions for the polymerization of pyrrole by iron(III) chloride in aqueous solution

The optimum initial mole ratio of iron(III)/pyrrole for the polymerization by aqueous iron(III) chloride solution at 19°C is shown to be approximately 2.38 ± 0.04. Thus the number of electrons transferred per pyrrole ring in the chemical synthesis of polypyrrole is consistent with values quoted for various electrochemical syntheses. It is shown that changing the initial mole ratio of the reactants affects the yield but not the chemical composition or conductivity of the polypyrrole powders. The extent of reaction as a function of time at two different reactant concentrations is also presented.