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  1. Abstract

    Lignin is the most abundant natural source of aromatics but remains underutilized. Elemental sulfur is a plentiful by-product of fossil fuel refining. Herein we report a strategy for preparing a durable composite by the one-pot reaction of elemental sulfur and lignin oil comprising lower molecular weight lignin derivatives. A lignin oil-sulfur composite (LOS90) was prepared by reacting 10 wt. % lignin oil with 90 wt. % elemental sulfur. The composite could be remelted and reshaped over several cycles without loss of properties. Results from the study showed thatLOS90has properties competitive with or exceeding values for commercial ordinary Portland cement and brick formulations. For example,LOS90displayed impressive compressive strength (22.1 MPa) and flexural strength (5.7 MPa).LOS90is prepared entirely from waste materials with 98.5% atom economy of composite synthesis, a lowEfactor of 0.057, and lignin char as the only waste product of the process for its preparation. These results suggest the potential applications of lignin and waste sulfur in the continuous efforts to develop more recyclable and sustainable materials.

     
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  2. Abstract

    Lignocellulosic biomass remains underutilized despite its annual production in gigaton quantities. Sulfur is another vastly underutilized waste product of fossil fuel refining. New mechanistic insight into the reactions of sulfur unveiled since 2020 suggest a rich and hitherto unexplored chemistry between biomass‐derived olefins and elemental sulfur. In this study, four biomass‐derived olefins (eugenol (1), 4‐allyl‐2,6‐dimethoxyphenol (2),o‐eugenol (3), and 2‐allyl‐6‐methylphenol(4)) were reacted with elemental sulfur to elucidate the S−C bond‐forming and other reactivity of these compounds. Each of the compounds was reacted with elemental sulfur in three sulfur : organic reactant ratios (2 : 1, 4 : 1 and 9 : 1) and at two temperatures (180 °C or 230 °C). Product mixtures were characterized using1H NMR spectrometry and GC‐MS analysis. Products resulting from a range of mechanisms were unveiled, including inverse vulcanization, S−Callylic/benzylicbond formation, S−Carylbond formation, intramolecular cyclization, C−C σ‐bond scission, and C−O σ‐bond scission. It is anticipated that the insights from this study will support further synergy between the critical sustainability goals of biomass and sulfur utilization.

     
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