Bisphenol A (BPA), a high use (~7.7 M metric tons in 2015) monomer, is industrially used to produce epoxy resins and polycarbonates. Its estrogenic and environmental effects motivated development of new monomers for the production of food safe polymeric liners and water bottles. Even with these new polymers, exposure to BPA is still a concern as it is used as a developer in thermal printer paper. Replacements are typically bisphenols with similar properties/structures producing comparable polymers and thermal developers. Like BPA, these bisphenols are produced from non-renewable petroleum resources. Recently, a greener synthetic route was reported that uses phenolic monomers derived from lignin: vanillyl alcohol and guaiacol were coupled via electrophilic aromatic substitution to produce bisguaicol (BG). This report prompted the design and synthesis of ten BG analogs. Analogs were synthesized under either biphasic (aqueous/organic) or neat (solvent free) conditions using an acidic solid phase resin as catalyst. Compounds were characterized by FTIR, 1H and 13C NMR, and melting point. BPA, BG, and BG analogs were screened using yeast engineered to express an estrogen receptor (ERα). The assay measured the induction of an active ERα dimer resulting in the formation of a colored species: plotting the color intensity vs. dose generated a dose-response curve and an EC50. These data were used to develop a structure-activity relationship. Screening data indicate that changing either the dipole moment or the substituent size on the BG analogs affects the estrogenicity. Several analogs were scaled up and treated with epichlorohydrin to give the bisepoxide monomer. Monomers were copolymerized with 4,4’-diaminodicyclohexylmethane to give epoxy resins. Future work includes characterization of the epoxy resins, design and synthesis of new monomers, and further screening using additional in vitro and in vivo assays.

Synthesis, screening, and polymerization of non-estrogenic BPA mimics

2019 Fall National Meeting

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