Synthesis of a sulfonated monomer to be polymerized into PEM electrolytes for use in fuel cells

CHED 824

Grace K. Mbogo and Robert W. Kopitzke, rkopitzke@winona.edu. Chemistry, Winona State University, Winona, MN 55987
The use of electro chemical cells (mainly fuel cells) as energy conversion devices is something that has been and still is under research. The type of fuel cell currently undergoing the most rapid development is the proton exchange membrane (PEM) fuel cell which contains a solid polymer electrolyte. The long-term goal of this work is to study the structure-property relationships of poly (aryl) ether based PEMs. This work will report on the proposed, four step synthesis of a sulfonated monomer. The first step is the synthesis of 4-bromo-4-fluorobenzophenone through a Friedel- Crafts acylation. This aryl bromide is converted into a boronic acid ester by a palladium catalyzed reaction. Suzuki coupling of two equivalents of the boronic acid ester with a dibenzyl halide yields the unsulfonated monomer. Sulfonation of this compound gives the sulfonic acid bearing target monomer.