Production of p‐Methylstyrene and p‐Divinylbenzene from Furanic Compounds

Abstract

A four-step catalytic process was developed to produce p-methylstyrene from methylfuran, a biomass-derived species. First, methylfuran was acylated over zeolite H-Beta with acetic anhydride. Second, the acetyl group was reduced to an ethyl group with hydrogen over copper chromite. Third, p-ethyltoluene was formed through Diels-Alder cycloaddition and dehydration of 2-ethyl-5-methyl-furan with ethylene over zeolite H-Beta. Dehydrogenation of p-ethyltoluene to yield p-methylstyrene completes the synthesis but was not investigated because it is a known process. The first two steps were accomplished in high yield (>88 %) and the Diels-Alder step resulted in a 67 % yield of p-ethyltoluene with a 99.5 % selectivity to the para isomer (final yield of 53.5 %). The methodology was also used for the preparation of p-divinylbenzene. It is shown that acylation of furans over H-Beta zeolites is a highly selective and high-yield reaction that could be used to produce other valuable molecules from biomass-derived furans.

Sustainable Production of o‐Xylene from Biomass‐Derived Pinacol and Acrolein

“…An elegant example is the production of p ‐xylene from biomass, involving a Diels–Alder (D–A) reaction and dehydration cascade of biomass‐derived 2,5‐dimethylfuran (DMF) with ethylene . Following this process, other valuable chemicals, such as aromatic carboxylic acids,– toluene, and styrene, can also be obtained from bio‐based furanics and dienophiles. Despite these impressive advances, the exploration of new sustainable routes to other bulk fossil‐derived aromatics is still in great demand.…”

Acetylene and Ethylene: Universal C2 Molecular Units in Cycloaddition Reactions

“…140` b c Alkyl-substituted furans 151 afforded the corresponding arenes 152 in moderate to excellent yields. 140` c d e f g h i Reactions were performed under high-pressure ethylene using zeolites, Brønsted acids, and Lewis acids as catalysts. Zeolite-based catalysts provided higher product yields than Brønsted and Lewis acids.…”

Substrate substitution effects in the Fries rearrangement of aryl esters over zeolite catalysts

“…7,8,27 The formation of these polymeric deposits stems from the presence of highly reactive ketenes, formed by the dissociation of acetylium species from protonated phenyl acetate and their subsequent decomposition. 8,27 In contrast to other acid-catalysed reactions over zeolite catalysts, in which precise structure-activity relationships have been established, for example with the concentrations and strengths of distinct acid site and the porous properties, [28][29][30][31][32][33][34] understanding of the Fries rearrangement remains limited. Currently, it is unclear where the reaction occurs on acid sites located within the micropores or on the external (non-microporous) surface of the zeolite crystal.…”