No abstract

Combination of the Passerini three component-reaction (3CR) and olefin metathesis led to the formation of poly[1-(alkyl carbamoyl)alkyl alkanoates], a new class of polyesters with amide moieties in their side chain, from renewable resources. Two different approaches were studied and compared to each other. First, monomers were synthesized by the Passerini-3CR and then polymerized via acyclic diene metathesis. Alternatively, bifunctional monomers were synthesized by self-metathesis and then polymerized by Passerini-3CR. Both approaches led to the formation of high-molecular-weight polymers. Moreover, Passerini-3CRs were shown to be a versatile grafting-onto method. The results clearly demonstrate that the Passerini-3CR offers an interesting new access to monomers and polymers and thus broadens the synthetic portfolio of polymer science.

A novel strategy is demonstrated to obtain polyamides with finely tunable structure using the Ugi fourcomponent reaction (Ugi-4CR). By the use of two bifunctional and two monofunctional components, six different combinations for the synthesis of polyamides via the Ugi-4CR are possible and were investigated in detail within this contribution. In contrast to conventional polyamide synthesis, this approach proceeds under very mild reaction conditions and without the use of a catalyst in a one-pot reaction. General applicability is shown by variation of the components, leading to finely tuned macromolecular structures (i.e., side groups and repeat units can be engineered). Finally, a facile introduction of clickable alkyne moieties is demonstrated, which was used for post-polymerization modification in an azide−alkyne cycloaddition, in order to demonstrate the high versatility of this approach.

The combination of the Ugi four-component reaction (Ugi-4CR) with acyclic diene metathesis (ADMET) or thiol-ene polymerization led to the formation of poly-1-(alkylcarbamoyl) carboxamides, a new class of substituted polyamides with amide moieties in the polymer backbone, as well as its side chains. 10-Undecenoic acid, obtained by pyrolysis of ricinoleic acid, the main fatty acid of castor oil, was used as the key renewable building block. The use of different primary amines, as well as isonitriles (isocyanides) for the described Ugi reactions provided monomers with high structural diversity. Furthermore, the possibility of versatile post-modification of functional groups in the side chains of the corresponding polymers should be of considerable interest in materials science. The obtained monomers were polymerized by ADMET, as well as thiol-ene, chemistry and all polymers were fully characterized. Finally, ortho-nitrobenzylamide-containing polyamides obtained by this route were shown to be photoresponsive and exhibited a dramatic change of their properties upon irradiation with light.

1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD)-catalyzed polycondensation reactions of fatty acid derived dimethyl dicarbamates and diols are introduced as a versatile, non-isocyanate route to renewable polyurethanes. The key step for the synthesis of dimethyl carbamate monomers from plant-oil-derived dicarboxylic acids is based on a sustainable base-catalyzed Lossen rearrangement. The formed polyurethanes with molecular weights up to 25 kDa are characterized by SEC, DSC, and NMR analysis.

A new strategy to obtain functionalized acrylate monomers is introduced using the Passerini three-component reaction (Passerini-3CR). This straightforward one-pot synthesis is characterized by excellent atom economy and structurally diverse products. By using acrylic acid and a variety of aldehydes and isocyanides, a set of several acrylate monomers was synthesized. Subsequent free radical polymerization yielded polyacrylates with tunable properties depending on the used components for the Passerini reaction. For instance, by varying the aldehyde component from acetaldehyde to heptanal, control over the glass transition in the final polymer was achieved. Moreover, for highly polar acrylate monomers a thermoresponsive behavior (upper critical solution temperature; UCST) was observed in methanol and/or ethanol.

A new, highly efficient and environmentally benign catalytic variant of the Lossen rearrangement is described. Dimethyl carbonate (DMC) as green activation reagent of hydroxamic acids in presence of catalytic amounts of tertiary amine bases {1,5,7-triazabicycloA quantities of methanol initiate the rearrangement. Methyl carbamates were obtained in good to moderate yields when aliphatic hydroxamic acids were employed in this catalytic Lossen rearrangement; under the same conditions aromatic hydroxamic acids yielded anilines. Notably, the mixture of DMC/methanol was recycled several times without observing decreased yields, thus minimizing the produced waste. Moreover, several other organic carbonates were successfully employed in the introduced catalytic Lossen rearrangement procedure.

Novel (co)polyesters are synthesized from rapeseed-derived renewable starting materials. Aliphatic monomers are obtained from oleic and erucic acid via thiol-ene addition, whereas ferulic acid is used for the synthesis of aromatic monomers. Copolyesters with different ratios of these monomers are prepared via base-catalyzed transesterifi cation reactions under neat conditions. Both monomer and polymer synthesis are optimized to achieve a high yield using environmentally benign synthetic procedures. A focus is put on applying less-toxic reagents (i.e., avoiding halogenated compounds) and on minimizing the produced waste, in order to meet the requirements of green chemistry. The resulting thioether-bearing (co)polyester series is analyzed, and fi nally oxidized to sulfone analogues. The thermal properties before and after oxidation are then compared. and thermal properties of the new (co)polyesters was performed.