Synthesis of a novel ferrocene derivative having flame‐retardant and smoke‐suppressant properties

Reaction of ferrocene with chlorendic anhydride (1,4,5,6,7,7‐hexachloro‐5‐norbornene‐2,3‐dicarboxylic acid anhydride) under Friedel–Crafts reaction conditions affords a new monosubstituted dervative of ferrocene which has significant flameretardant and smoke‐suppressant properties when incorporated into poly(vinyl chloride) (PVC). The monocarboxylic acid from the above reaction undergoes smooth methylation with diazomethane to give the corresponding methyl ester. 1 H and 13 C NMR spectra of these compounds have been compared with those obtained from similar compounds, namely β‐ferrocenoylpropanoic acid and its methyl ester. Distant asymmetric centres in the chlorendic anhydride substituent markedly affect the proton spectra of the ferrocene derivative.