21583-35-7Relevant academic research and scientific papers
Catalytic upcycling of PVC waste-derived phthalate esters into safe, hydrogenated plasticizers
Bals, Sara,De Vos, Dirk E.,Diefenhardt, Thomas,Jain, Noopur,Marquez, Carlos,Schlummer, Martin,Windels, Simon
, p. 754 - 766 (2022/02/02)
Recycling of end-of-life polyvinyl chloride (PVC) calls for solutions to deal with the vast amounts of harmful phthalate plasticizers that have historically been incorporated in PVC. Here, we report on the upcycling of such waste-extracted phthalate esters into analogues of the much safer diisononyl 1,2-cyclohexanedicarboxylate plasticizer (DINCH), via a catalytic one-pot (trans)esterification-hydrogenation process. For most of the virgin phthalates, Ru/Al2O3 is a highly effective hydrogenation catalyst, yielding >99% ring-hydrogenated products under mild reaction conditions (0.1 mol% Ru, 80 °C, 50 bar H2). However, applying this reaction to PVC-extracted phthalates proved problematic, (1) as benzyl phthalates are hydrogenolyzed to benzoic acids that inhibit the Ru-catalyst, and (2) because impurities in the plasticizer extract (PVC, sulfur) further retard the hydrogenation. These complications were solved by coupling the hydrogenation to an in situ (trans)esterification with a higher alcohol, and by pretreating the extract with an activated carbon adsorbent. In this way, a real phthalate extract obtained from post-consumer PVC waste was eventually completely (>99%) hydrogenated to phthalate-free, cycloaliphatic plasticizers. This journal is
Selective monoesterification of dicarboxylic acids catalysed by ion-exchange resins
Nishiguchi, Takeshi,Ishii, Yasuhiro,Fujisaki, Shizuo
, p. 3023 - 3027 (2007/10/03)
Symmetrical dicarboxylic acids with 4-14 carbon atoms gave selectively the corresponding monoesters in high yields in the transesterification catalysed by strongly acidic ion-exchange resins in ester-hydrocarbon mixtures. It was found that the rate of the esterification of the dicarboxylic acids is much higher than that of the monocarboxylic acids formed. This result can explain the high selectivity for the monoester formation and can also be explained by the existence of an aqueous layer on the surface of the resins. This method of selective esterification is quite simple and practical. The Royal Society of Chemistry 1999.
