Alkoxide-Initiated Regioselective Coupling of Carbon Disulfide and Terminal Epoxides for the Synthesis of Strongly Alternating Copolymers

作者：Diebler Johannes; Komber Hartmut; Haeussler Liane; Lederer Albena; Werner Thomas

来源：Macromolecules, 2016, 49(13): 4723-4731.

DOI：10.1021/acs.macromol.6b00728

The synthesis of highly regioregular and alternating polythiocarbonates from carbon disulfide and terminal epoxides has been achieved. The copolymerizations were performed under ambient and solvent-free conditions in the presence of (LiOBu)-Bu-t (0.125-0.5 mol %) as initiator. At higher loadings the reaction pathway switched in favor to the catalytic formation of cyclic dithiocarbonates. Under optimized reaction conditions polymers with molecular weights up to 109 kg mol(-1) were isolated. The NMR spectroscopic analysis of the polythiocarbonates revealed that 94% of backbone structure is formed by strongly alternating head-to-head arrangement of epoxypropane and 1,2-epoxybutane monomers, respectively, at a thiocarbonate group -CHR-OC(S)O-CHR- and tail-to-tail arrangement at a. trithiocarbonate group -CH2-SC(S)S-CH2-. Atactic polymers were obtained using racemic mixtures of the epoxides, but an isotactic polymer was obtained when chiral (R)-epoxypropane was converted. A mechanism is proposed which rationalizes the regio- and stereochemistry observed for the alkoxide-initiated copolymerization of CS2 and terminal epoxides.

• 出版日期2016-7-12