Biobased Amines: From Synthesis to Polymers; Present and Future

Deaminative Strategy for the Visible-Light-Mediated Generation of Alkyl Radicals

A deaminative strategy for the visible-light-mediated generation of alkyl radicals from redox-activated primary amine precursors is described. Abundant and inexpensive primary amine feedstocks, including amino acids, were converted in a single step into redox-active pyridinium salts and subsequently into alkyl radicals by reaction with an excited-state photocatalyst. The broad synthetic potential of this protocol was demonstrated by the alkylation of a number of heteroarenes under mild conditions.

Isohexide Dinitriles: A Versatile Family of Renewable Platform Chemicals

Building blocks of isohexides extended by one carbon atom at the 2- or 5-positions are now synthetically accessible by a convenient, selective, base-catalyzed epimerization of the corresponding dinitriles. Kinetic experiments using the strong organic base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) show that all three possible isohexide dinitrile isomers exist within a dynamic equilibrium. An epimerization mechanism based on density functional theory (DFT) calculations is proposed. Structural identification of all three possible isomers is based on NMR analysis and single crystal x-ray crystallography. DFT calculations confirm that the observed crystal structures are indeed the lowest energy conformers of these isohexide derivatives.

Chemocatalytic Conversion of Cellulosic Biomass to Methyl Glycolate, Ethylene Glycol, and Ethanol

Production of chemicals and fuels from renewable cellulosic biomass is important for the creation of a sustainable society, and it critically relies on the development of new and efficient transformation routes starting from cellulose. Here, a chemocatalytic conversion route from cellulosic biomass to methyl glycolate (MG), ethylene glycol (EG), and ethanol (EtOH) is reported. By using a tungsten-based catalyst, cellulose is converted into MG with a yield as high as 57.7 C % in a one-pot reaction in methanol at 240 °C and 1 MPa O₂ , and the obtained MG can be easily separated by distillation. Afterwards, it can be nearly quantitatively converted to EG at 200 °C and to EtOH at 280 °C with a selectivity of 50 % through hydrogenation over a Cu/SiO₂ catalyst. By this approach, the fine chemical MG, the bulk chemical EG, and the fuel additive EtOH can all be efficiently produced from renewable cellulosic materials, thus providing a new pathway towards mitigating the dependence on fossil resources.

Rearrangement of Benzylic Trichloroacetimidates to Benzylic Trichloroacetamides

The rearrangement of allylic trichloroacetimidates is a well-known transformation, but the corresponding rearrangement of benzylic trichloroacetimidates has not been explored as a method for the synthesis of benzylic amines. Conditions that provide the trichloroacetamide product from a benzylic trichloroacetimidate in high yield have been developed. Methods were also investigated to transform the trichloroacetamide product directly into the corresponding amine, carbamate, and urea. A cationic mechanism for the rearrangement is implicated by the available data.

Polymers from sugars: cyclic monomer synthesis, ring-opening polymerisation, material properties and applications

This feature article gives an overview of sugar-based polymers that can be made by ring-opening-polymerisation and their applications.

Interplay between crystallization and the Diels–Alder reaction in biobased multiblock copolyesters possessing dynamic covalent bonds

Biobased multiblock copolyesters possessing physical cross-links via crystallization and chemical cross-links via the Diels–Alder reaction at the same time.