Preparation of polyaniline by oxidation of aniline using H₂O₂ in the presence of an iron(II) catalyst

Oxidative polymerization of aniline using the H 2 O 2 ‐FeSO 4 system gave polyaniline under mild conditions. The prepared powdery emeraldine base, a form of polyaniline, is blue black and shows high solubility in organic solvents (e.g., ca. 200 mg/mL in N ‐methylpyrrolidone). The number‐average molecular weight ( M n ) of the polymer obtained was 1,3–1,7 · 10 4 (via gel permeation chromatography vs. polystyrene) and M w / M n = 1,6–2,2. Poly(2‐ethylaniline) and poly‐(2‐propylaniline) with high molecular weights were also synthesized by this procedure in high yield.