Furandicarboxylate Polyesters: A Comprehensive ADMET Study of a Novel Class of Furan-Based α,ω-Diene Monomers

The present research article delves into the preparation of a new class of bio-based polyesters from α,ω-diene furandicarboxylate monomers. In particular, it exploits the use of acyclic diene metathesis polymerisation (ADMET) on 2,5-furandicarboxylic acid (FDCA)-derived compounds. First, a library of furan-based α,ω-diene monomers was prepared via acid- or base-catalyzed transesterification of 2,5-furandicarboxylic acid dimethyl ester (FDME) with commercially available alcohols incorporating terminal olefins, i. e., allyl alcohol, but-3-en-1-ol, hex-5-en-1-ol and dec-9-en-1-ol. Then, the novel monomers were subjected to ADMET polymerisation employing different catalysts and reaction conditions. Interestingly, first-generation Grubbs catalyst was found to be the best promoter for ADMET polymerisation. This catalyst allowed the preparation of a new family of bio-based polyesters with molecular weights up to 26.4 kDa, with good thermal stability, and adaptable cis-trans conformations. Results also revealed that the monomer structure had a direct impact on the polymerisation efficiency and the resulting thermal properties. The effect of green bio-based solvents such as Cyrene™, dimethyl isosorbide (DMI) and γ-valerolactone (GVL) on the polymerisation process was also studied. Data collected showed that the solvent concentration influenced both the yield and length of polymers formed. Furthermore, some co-polymerisation experiments were conducted; the successful integration of different monomers in the resulting copolymer was shown to affect the glass transition temperature (Tg) of the resulting materials.

Green Synthesis of UV-Reactive Polycarbonates from Levoglucosenone and 5-Hydroxymethyl Furfural

This study focuses on the synthesis of fully renewable polycarbonates (PCs) starting from cellulose-based platform molecules levoglucosenone (LGO) and 2,5-bis(hydroxymethyl)furan (BHMF). These unique bio-based PCs are obtained through the reaction of a citronellol-containing triol (Triol-citro) derived from LGO, with a dimethyl carbonate derivative of BHMF (BHMF-DC). Solvent-free polymerizations are targeted to minimize waste generation and promote an eco-friendly approach with a favorable environmental factor (E-factor). The choice of metal catalyst during polymerization significantly influences the polymer properties, resulting in high molecular weight (up to 755 kDa) when Na2 CO3 is employed as an inexpensive catalyst. Characterization using nuclear magnetic resonance confirms the successful incorporation of the furan ring and the retention of the terminal double bond of the citronellol pendant chain. Furthermore, under UV irradiation, the presence of both citronellol and furanic moieties induces singular structural changes, triggering the formation of three distinct structures within the polymer network, a phenomenon herein occurs for the first time in this type of polymer. These findings pave the way to new functional materials prepared from renewable monomers with tunable properties.

Replacement of Less-Preferred Dipolar Aprotic and Ethereal Solvents in Synthetic Organic Chemistry with More Sustainable Alternatives

Dipolar aprotic and ethereal solvents comprise just over 40% of all organic solvents utilized in synthetic organic, medicinal, and process chemistry. Unfortunately, many of the common "go-to" solvents are considered to be "less-preferable" for a number of environmental, health, and safety (EHS) reasons such as toxicity, mutagenicity, carcinogenicity, or for practical handling reasons such as flammability and volatility. Recent legislative changes have initiated the implementation of restrictions on the use of many of the commonly employed dipolar aprotic solvents such as dimethylformamide (DMF) and N-methyl-2-pyrrolidinone (NMP), and for ethers such as 1,4-dioxane. Thus, with growing legislative, EHS, and societal pressures, the need to identify and implement the use of alternative solvents that are greener, safer, and more sustainable has never been greater. Within this review, the ubiquitous nature of dipolar aprotic and ethereal solvents is discussed with respect to the physicochemical properties that have made them so appealing to synthetic chemists. An overview of the current legislative restrictions being imposed on the use of dipolar aprotic and ethereal solvents is discussed. A variety of alternative, safer, and more sustainable solvents that have garnered attention over the past decade are then examined, and case studies and examples where less-preferable solvents have been successfully replaced with a safer and more sustainable alternative are highlighted. Finally, a general overview and guidance for solvent selection and replacement are included in the Supporting Information of this review.

Chemocatalytic value addition of glucose without carbon-carbon bond cleavage/formation reactions: an overview

As the monomeric unit of the abundant biopolymer cellulose, glucose is considered a sustainable feedstock for producing carbon-based transportation fuels, chemicals, and polymers. The chemocatalytic value addition of glucose can be broadly classified into those involving C-C bond cleavage/formation reactions and those without. The C6 products obtained from glucose are particularly satisfying because their syntheses enjoy a 100% carbon economy. Although multiple derivatives of glucose retaining all six carbon atoms in their moiety are well-documented, they are somewhat dispersed in the literature and never delineated coherently from the perspective of their carbon skeleton. The glucose-derived chemical intermediates discussed in this review include polyols like sorbitol and sorbitan, diols like isosorbide, furanic compounds like 5-(hydroxymethyl)furfural, and carboxylic acids like gluconic acid. Recent advances in producing the intermediates mentioned above from glucose following chemocatalytic routes have been elaborated, and their derivative chemistry highlighted. This review aims to comprehensively understand the prospects and challenges associated with the catalytic synthesis of C6 molecules from glucose.

Sustainable Hyperbranched Functional Materials via Green Polymerization of Readily Accessible Levoglucosenone-Derived Monomers

The homopolymerization in basic conditions of the recently reported bis(γ-lactone), 2H-HBO-HBO, is herein described for the first time. The solvent-free polymerization of this pentafunctional levoglucosenone (LGO) derivative affords fully renewable poly(vinyl-ether lactone) copolymers with a highly hyperbranched structure. This investigation stems from the polycondensation trials between 2H-HBO-HBO and di(methyl carbonate) isosorbide (DCI) that fails to give the anticipated polycarbonates. Such unexpected behavior is ascribed to the higher reactivity of the 2H-HBO-HBO hydroxy groups toward its α,β-conjugated endocyclic C═C, rather than the DCI methylcarbonate moieties. The different mechanistic scenarios involved in 2H-HBO-HBO homopolymerization are addressed and a possible structure of poly(2H-HBO-HBO) is suggested. Furthermore, the readily accessible (S)-γ-hydroxymethyl-α,β-butenolide (HBO) is also polymerized for the first time at a relatively large scale, without any prior modification, resulting in a new hyperbranched polymer with an environmental factor (E factor) ≈0. These new HBO-based polymers have a great potential for industrial-scale production due to their interesting properties and easy preparation via a low-cost, green, and efficient process.