A family of lignin-based polyols (LBPs) has been prepared and characterized by a novel and unprecedented synthetic approach consisting of a cationic ring opening polymerization reaction of oxiranes in the...
The chemical fixation of carbon dioxide by cycloaddition to biobased epoxides, e.g., vegetable oils, fatty acids, etc., is an efficient, sustainable, and clean strategy to obtain biobased cyclic carbonates. These can be used as feedstocks for the synthesis of environmentally friendly biobased polymers as an alternative to polymers used in daily life such as polyurethanes (PUs) and/or polycarbonates (PCs). Nevertheless, this reaction is not trivial at all due to both the low reactivity of the CO 2 molecule and the nature of the needed substrates (biobased epoxides) where the epoxide groups are internal and sterically hindered, hampering the CO 2 cycloaddition reaction. Therefore, the design of efficient catalytic systems to overcome these hurdles is mandatory. Most of the catalytic systems developed for this transformation aim to facilitate the rate-determining step in the CO 2 cycloaddition catalytic cycle. They comprise an ionic liquid or an ionic compound with a nucleophilic anion alone or in the presence of a cocatalyst to assist the epoxide ring-opening. The most commonly used catalyst is tetrabutylammonium bromide [TBA][Br] ionic liquid, but other ammonium-, phosphonium-, and sulfonium-based ionic liquids in combination or not with a cocatalyst have also been disclosed in the literature. This Review presents a structured overview of the reported catalytic systems, both homogeneous and heterogeneous catalysts, employed in the transformation of any epoxidized vegetable oil or derivates into biobased carbonated materials. The different catalytic systems have been discussed and compared in terms of catalytic performance, employed substrates, and reaction conditions.
The epoxidation of vegetable oils is a chemical or biochemical reaction where oil triglycerides are converted into more reactive molecules. These will be further transformed into a broad variety of products with significant potential for industrial applications. The epoxidation of vegetable oils consists of a commercially established process that uses homogeneous mineral acids as catalysts. In this paper, different strong acidic ion exchange resins were evaluated as alternatives to substitute the commercial homogeneous catalysts. Amberlyst 39 was selected as the most promising one to explore the effect of the variables such as temperature, acetic acid, or hydrogen peroxide concentration in sunflower oil epoxidation. The optimal operational conditions that maximized the conversion and oxirane yield were determined. Then, these values were applied in several catalyst reuses for establishing the resin durability. Results show that by employing ion exchange resins, excellent product yields and selectivity are obtained, minimizing post‐reaction purification needs.
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