Trends in Polymers 2017/2018: Polymer Synthesis

Additive-Free Construction of Tetrahydropyrimidine Skeleton by using 1,3,5-Triazinane as Four-Atom Synthon

Herein, an unprecedented [4 + 2] cycloaddition of enaminone with 1,3,5-triazinane has been developed. The representative semihydrogenated aromatic heterocycle 1,2,3,4-tetrahydropyrimidines have been synthesized with a broad substrate scope, demonstrating potential antitumor activity. This approach has been smoothly conducted under additive-free and environmentally friendly conditions that are compatible with various functional groups. Furthermore, the condition optimization process reveals that the tetrahydropyrimidine product is regulated via the reaction temperature.

Highly efficient oxidation of 2,2'-hydrazobis-isobutyronitrile to 2,2'-azobis-isobutyronitrile over a CrOx/TiO2 catalyst with hydrogen peroxide

Green oxidation of 2,2'-hydrazobis-isobutyronitrile (HAIBN) to 2,2'-azobis-isobutyronitrile (AIBN) over a recyclable solid catalyst was a significant challenge. A titanium dioxide-supported chromium oxide (CrOx/TiO2) catalyst was, for the first time, developed for oxidation of HAIBN with hydrogen peroxide and achieved complete conversion of HAIBN with a high (94.8%) yield of AIBN.

Anionic Copolymerization of Styrene Sulfide with Elemental Sulfur (S8)

The superior ability of thiiranes (episulfides) to undergo ring-opening polymerization (ROP) in the presence of anionic initiators allows the preparation of chemically stable polysulfide homopolymers. Incorporation of elemental sulfur (S₈) by copolymerization below the floor temperature of S₈ permits the placement of a large quantity of sulfur atoms in the polysulfide mainchain. The utility of styrene sulfide (2-phenylthiirane; StS) for copolymerization with elemental sulfur is reported here. A few polysulfides differing depending on the initial ratio of S₈ to StS and copolymerization time were synthesized. Various spectroscopic methods (¹H NMR, ¹³C NMR, Raman spectroscopy and FTIR spectroscopy) were applied to characterize the chemical structure of the copolymers. Additionally, the phase structure and thermal stability of the synthesized polysulfides were investigated using DSC and TGA, respectively. The successful anionic copolymerization of styrene sulfide and elemental sulfur has been demonstrated.