Synthesis of a Number of 3‐Alkyl Substituted Pyrrole Monomers

Abstract

The problem of delamination of electro-deposited polypyrrole (PPY) layers on several substrates can be avoided by using an adhesion promoting system. A new class of compounds-ω-(pyrrol-3-yl)alkylphosphonic acids have been designed to link polypyrrole layers covalently to metal oxide surfaces. Synthetic routes, which lead to the formation of 3-substituted pyrroles with surface active groups are described. The synthesis and characterization are shown in detail. 1-Phenylsulfonyl pyrrole was utilized as a precursor in the synthesis of 3-substituted pyrroles via Friedel-Crafts acylation reaction. Subsequently, two methods were used to synthesize ω-(pyrrol-3-yl)alkylphosphonic acid esters. One starts from the brominated oxoalkyl derivatives by removing the protecting group followed by reduction yielding ω-(pyrrol-3-yl)alkylphosphonic acid esters. This method is suitable for hexyl or longer chain derivatives. The other is the reduction of carbonyl group followed by de-protection, which is successful for short as well as long chain derivatives. Finally, ω-(pyrrol-3-yl)alkylphosphonic acids were obtained by hydrolysis of the ester derivatives.