Chemically Recyclable Poly(β-thioether ester)s Based on Rigid Spirocyclic Ketal Diols Derived from Citric Acid.

Incorporating rigid cyclic acetal and ketal units into polymer structures is an important strategy toward recyclable high-performance materials from renewable resources. In the present work, citric acid, a widely used platform chemical derived from biomass, has been efficiently converted into di- and tricyclic diketones. Ketalization with glycerol or trimethylolpropane afforded rigid spirodiols, which were obtained as complex mixtures of isomers.

Impact of short-term heat treatment on the structure and functional properties of commercial furcellaran compared to commercial carrageenans.

In the production of biopolymers, the processing operations (e.g. extraction and drying) involve some degradation of the polysaccharide-causing structural and functional changes in final products.

Designed whole-cell-catalysis-assisted synthesis of 9,11-secosterols.

A method for the synthesis of 9,11-secosteroids starting from the natural corticosteroid cortisol is described. There are two key steps in this approach, combining chemistry and synthetic biology. Stereo- and regioselective hydroxylation at C9 (steroid numbering) is carried out using whole-cell biocatalysis, followed by the chemical cleavage of the C-C bond of the vicinal diol.

Shortfall of B3LYP in Reproducing NMR J Couplings in Some Isomeric Epoxy Structures with Strong Stereoelectronic Effects: A Benchmark Study on DFT Functionals.

Unprecedented scatter plots of calculated versus measured NMR J coupling constants in six densely oxygen functionalized epoxides are found with some B3LYP protocols, an effect attributed to stereoelectronic effects. Hence, 26 other exchange-correlation density functionals (xc DFs) are benchmarked in this work. Very good results are achieved with mPW1PW91 and PBE0 in conjunction with the pcJ-1 basis set (BS) of moderate size.

Hydroformylation of Olefinic Derivatives of Isosorbide and Isomannide.

The first time application of hydroformylation on olefinic derivatives of isosorbide and isomannide is shown by which a new carbon-carbon bond is formed. Depending on the ligand and reaction conditions used, the C6 regioisomer a can be obtained in 4:1 ratio and excellent yield, whereas C5 isomer b is achieved in almost complete regioselectivity (46:1) and good yield. In the majority of cases only the exo orientation is observed for the obtained aldehydes, and the method is easily applicable also on a 1 g scale.