Production of para-methylstyrene and para-divinylbenzene from furanic compounds

2017 Spring Symposium

Molly Koehle and Raul Lobo, Chemical and Biomolecular Engineering, University of Delaware, Newark, DE

Abstract – Of the three isomers of methylstyrene, para-methylstyrene is highly desirable because it yields polymers with superior properties over polystyrene and mixed poly-methylstyrene [1]. However, controlling the substitution of methylstyrene via direct acylation or alkylation of toluene is difficult because even though the para isomer is favored, meta and ortho isomers are also formed [1, 2], and separation of the isomer mixture is very difficult due to their nearly identical properties.

The Diels-Alder cycloaddition and dehydration of substituted furans with ethylene is a plausible route to p-methylstyrene since it is inherently selective to para aromatic species. We have successfully developed a three-step catalytic route to p-methylstyrene from methylfuran (Scheme 1) at high yield and very high isomer selectivity. The process uses Friedel-Crafts acylation, selective reductions with hydrogen and Diels-Alder cycloaddition with ethylene. The raw materials—furans, ethylene and acetic acid—can all be derived from biomass [3,4], thus allowing ‘green’ styrene production from renewable carbon sources. This approach has also been extended to the production of p-divinylbenzene. As the acylation step is known to be catalyzed by Lewis acids, recent work has focused on studying this step on Brønsted and Lewis acid zeolites and will be presented as well.

Scheme 1: Production of para-methylstyrene from methylfuran

References:
[1] W.W. Kaeding and G.C. Barile, in: B.M. Culbertson and C.U. Pittman, Jr. (Eds.), New Monomers and Polymers, Plenum Press, New York, NY, 1984, pp. 223-241.
[2]“Aromatic Substitution Reactions.” http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/benzrx1.htm
[3] A.A. Rosatella; S.P. Simeonov; R.F.M. Frade, R.F.M..; C.A.M. Afonso, Green Chem., 13 (2011) 754.
[4] C.H. Christensen; J. Rass-Hansen; C.C. Marsden; E. Taarning; K. Egeblad, ChemSusChem, 1 (2008) 283.

Biography – Molly obtained her B.S. in Chemical Engineering from the University of Pittsburgh and her M.S. in Chemical Engineering from the University of Connecticut. She has worked at the Catalysis Center for Energy Innovation in Prof. Raul Lobo’s group since 2013. Her work focuses on transformations of biomass to fuels and chemicals with Bronsted and Lewis acid zeolites.