Isothiocyanates were snythesized in a more sustainable manner by sulfurization of isocyanides with elemental sulfur using catalytic amounts of DBU (down to 2 mol%).
An easy access to
thermoplastic polythiosemicarbazones (polyTSCs)
is presented by condensation of dithiosemicarbazides and aromatic
dialdehydes, yielding eight polyTSCs and five co-polyTSCs, exhibiting M
ns up to 38 kDa in good yields (58–93%).
The polymerization proceeds at room temperature and is typically finished
after 2–3 h. The monomer scope was investigated, revealing
broad moiety tolerance (aliphatic, cyclic, benzylic, and aromatic
groups). Full characterization was performed by proton and carbon
NMR spectroscopy, IR spectroscopy, and size exclusion chromatography,
confirming the anticipated chemical structure of polyTSCs. Thermal
analysis of the polymers showed degradation starting at ∼200
°C by decomposition of the TSC function. Glass transitions were
only observed for polymers derived from rigid monomers (162–198
°C). Further versatility of the reaction was underlined by the
synthesis of five copolymers using different dithiosemicarbazide monomers.
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