The use of sustainable metal-based catalysts for the synthesis of five-membered ring containing cyclic carbonates from epoxides and carbon dioxide is critically reviewed. Coverage is restricted to catalysis by the abundant metals: sodium, potassium, aluminium, calcium, titanium and iron and the relative merits and limitations of each catalyst syste m are compared.

We have developed a heterogeneous silica catalyst that can effectively catalyse amide synthesis from acid and amine, without production of toxic by-products and with the advantage of being readily available, low cost, environmentally benign and reusable.

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A family of monomers, including 2,5-hexandiol, 2,7-octandiol, 2,5-furandicarboxylic acid (FDCA), terephthalic acid (TA), and branched-chain adipic and pimelic acid derivatives, all find a common derivation in the biomass-derived platform molecule 5-(chloromethyl)furfural (CMF). The diol monomers, previously little known to polymer chemistry, have been combined with FDCA and TA derivatives to produce a range of novel polyesters. It is shown that the use of secondary diols leads to polymers with higher glass transition temperatures (T) than those prepared from their primary diol equivalents. Two methods of polymerisation were investigated, the first employing activation of the aromatic diacids via the corresponding diacid chlorides and the second using a transesterification procedure. Longer chain diols were found to be more reactive than the shorter chain alternatives, generally giving rise to higher molecular weight polymers, an effect shown to be most pronounced when using the transesterification route. Finally, novel diesters with high degrees of branching in their hydrocarbon chains are introduced as potential monomers for possible low surface energy materials applications.

The renaissance of the bio-based chemical industry over the last 20 years has seen an ever growing interest in the synthesis of new bio-based polymers. The building blocks of these new polymers, so called platform molecules, contain significantly more chemical functionality than their petrochemical counterparts (such as ethene, propene and para-xylene). As a result bio-based polymers often contain greater residual chemical functionality in their chains, with groups such as alkenes and hydroxyls commonly observed. These functional groups can act as sites for post-polymerization modification (PPM), thus further extending the range of applications for bio-based polymers by tailoring the polymers' final properties. This mini-review highlights some of the most recent and compelling examples of how to make use of bio-based polymers with residual functional groups for PPM. It also looks at how the emerging interdisciplinary field of enzymatic polymer synthesis allows for increased functionality in polymers by avoiding side-reactions as a result of milder reaction conditions, and additionally offers an alternative means of polymer surface modification.

Enzymatic synthesis of unsaturated polyesters and the temperature-dependent reversibility of the aza-Michael addition of diethyl amine pendants.

Biocatalyzed synthesis of aliphatic and furan-based polyesters in safer, bio-derived solvents for the substitution of toluene and tetrahydrofuran.

Following concerns over increasing global plastic pollution, interest in the production and characterization of bio-based and biodegradable alternatives is rising. In the present work, the synthesis of a series of fully bio-based alternatives based on 2,4-, 2,5-, and 2,6-pyridinedicarboxylic acid-derived polymers produced via enzymatic catalysis are reported. A similar series of aromatic-aliphatic polyesters based on diethyl-2,5-furandicarboxylate and of the petroleum-based diethyl terephthalate and diethyl isophthalate were also synthesized. Here we show that the enzymatic synthesis starting from 2,4-diethyl pyridinedicarboxylate leads to the best polymers in terms of molecular weights (M n = 14.3 and M w of 32.1 kDa when combined with 1,8-octanediol) when polymerized in diphenyl ether. Polymerization in solventless conditions were also successful leading to the synthesis of bio-based oligoesters that can be further functionalized. DSC analysis show a clear similarity in the thermal behavior between 2,4-diethyl pyridinedicarboxylate and diethyl isophthalate (amorphous polymers) and between 2,5-diethyl pyridinedicarboxylate and diethyl terephthalate (crystalline polymers).