Preparation of glycerol carbonate esters by using hybrid Nafion-silica catalyst

Five-Membered Cyclic Carbonates: Versatility for Applications in Organic Synthesis, Pharmaceutical, and Materials Sciences

This review presents the recent advances involving several applications of five-membered cyclic carbonates and derivatives. With more than 150 references, it covers the period from 2012 to 2020, with special emphasis on the use of five-membered cyclic carbonates as building blocks for organic synthesis and material elaboration. We demonstrate the application of cyclic carbonates in several important chemical transformations, such as decarboxylation, hydrogenation, and transesterification reactions, among others. The presence of cyclic carbonates in molecules with high biological potential is also displayed, together with the importance of these compounds in the preparation of materials such as urethanes, polyurethanes, and flame retardants.

Chemoenzymatic Synthesis of 5-Hydroxymethylfurfural (HMF)-Derived Plasticizers by Coupling HMF Reduction with Enzymatic Esterification

Biobased plasticizers, as substitutes for phthalates, have been synthesized from 5-hydroxymethylfurfural (HMF) and carboxylic acids (or esters) through a chemoenzymatic cascade process that involves as its first step the reduction of 5-hydroxymethylfurfural into 2,5-bis(hydroxymethyl)furan (BHMF), followed by the esterification of BHMF with carboxylic acids (or esters) by using a supported lipase (Novozym 435). The reduction of HMF into BHMF is performed by using monodisperse metallic Co nanoparticles with a thin carbon shell (Co@C) with high activity and selectivity. After optimization of reaction conditions (temperature, hydrogen pressure, and solvent), it is possible to achieve 97 % conversion of HMF with 99 % selectivity to BHMF after 2 h reaction time. The reduction of HMF and esterification of BHMF using carboxylic acids or vinyl esters as acyl donors by lipase are optimized separately in batch and in fixed-bed continuous reactors. The coupling of two flow reactors (for reduction and subsequent esterification) working under optimized reaction conditions affords the diesters of BHMF in roughly 90 % yield with no loss of activity during 60 h of operation.

Transforming Methyl Levulinate into Biosurfactants and Biolubricants by Chemoselective Reductive Etherification with Fatty Alcohols

Biomass-derived surfactants with very good surface tension and critical micellar concentration properties were obtained by conversion of methyl levulinate into methyl 4-alkoxypentanoates through reductive etherification with aliphatic alcohols. Among different bifunctional acid/metal catalysts best results were obtained with Pd on carbon bearing acid sites. The reaction occurred through the formation of an enol ether intermediate followed by hydrogenation. Pd in high-density planes was the active hydrogenation species, and an optimum crystal size was found to be approximately 10 nm. The reductive etherification with aliphatic alcohols was extended to other aliphatic and cyclic ketones and aldehydes obtained from biomass, and excellent results were obtained on supported Pd catalysts with the reaction route and experimental conditions described in this work.

First Attempt of Glycidol-to-Monoalkyl Glyceryl Ethers Conversion by Acid Heterogeneous Catalysis: Synthesis and Simplified Sustainability Assessment

The selective preparation of monoalkylglyceryl ethers (MAGEs) is a task for researchers owing to their broad range of applications. In this work, green feedstocks such as glycidol and alcohols were used to prepare MAGEs under mild reaction conditions (80 °C, 3 h, 0.5 mol % catalyst) in the presence of acid heterogeneous catalysts. Nafion shows the best performances in terms of conversion and selectivity to MAGES and also high stability. A comparison of the environmental performances with the most consolidated pathway from glycerol has shown that the usage of glycidol (recovered as a value-added product from Epicerol process) and Nafion leads to a lower impact on ecosystems. In addition, results achieved from a simplified socio-economic analysis show that the innovative route here proposed has potential (at the laboratory scale) of enhancing potential gains and of reducing the social implications resulting from externalities associated with environmental impacts (e.g., CO₂ equivalents).

Silica-immobilized Aquivion PFSA superacid: application to heterogeneous direct etherification of glycerol with n-butanol

Silica-immobilized Aquivion® resin with high mesoporosity and acid-site accessibility demonstrated good activity, selectivity and reusability for glycerol etherification withn-butanol.

Process intensification for tertiary amine catalyzed glycerol carbonate production: translating microwave irradiation to a continuous-flow process

Different products of interest can be produced from glycerol and glycerol carbonate (GC) has received much attention in recent years because of its physical properties, nontoxicity and water solubility.