Wonmun Choi

Addition of five-membered cyclic carbonate with amine and its application to polymer synthesis

A bifunctional five-membered cyclic carbonate was synthesized from carbon dioxide and diglycidyl terephthalate, and its polyaddition with alkyl diamines were carried out in DMF at room temperature to obtain the corresponding poly(hydroxyurethane)s with Mn s in the range of 6300–13200 in good yields. The structures of the obtained polymers were confirmed by IR and NMR spectroscopy and their glass-transition and decomposition temperatures were observed at 3–29 °C and 182–277 °C, respectively.

A novel one‐pot oxidation polymerization of dithiols obtained from bifunctional five‐membered cyclic dithiocarbonates with amines

One-pot oxidation polymerization of dithiols, obtained from bifunctional five-membered cyclic dithiocarbonates (4a and 4b) with two equivalents of amines, was studied. The monomers 4a and 4b were synthesized by the reactions of bisphenol A diglycidyl ether and neopentyl glycol diglycidyl ether with carbon disulfide, respectively. Polydisulfides with M n s 4600-20,200 were obtained quantitatively in the oxidation polymerization of the dithiols obtained in situ by the reactions of 4a with benzylamine, n -butylamine, and piperidine. On the other hand, dithiols obtained from 4b with benzylamine, afforded cyclic disulfides as well as the polydisulfide under similar conditions.

New Transformation of 1,3‐Oxathiolane‐2‐thione into 1,3‐Dithiolan‐2‐one via Polymerization and Depolymerization

This article deals with the cationic and anionic depolymerization of polydithiocarbonate, which was synthesized by cationic polymerization of 5-phenoxymethyl-1,3-oxathiolane-2-thione (1) using methyl triflate as the initiator. The cationic depolymerization of the obtained polymer was carried out in the presence of 5-20 mol-% of methyl triflate or triflic acid catalyst in chlorobenzene at 60 °C for 96 h to afford 4-phenoxymethyl-1,3-dithiolan-2-one (2) in 35-83% yield. The anionic depolymerization of the polymer was carried out in the presence of 5 mol-% of triethylamine or potassium tert-butoxide at 20 °C for 24 h to afford 2 in 85-100% yield.

Living ring‐opening polymerization based on neighboring group participation

Cationic ring-opening polymerization of a five-membered cyclic dithiocarbonate having benzoxymethyl group; 5-benzoxymethyl-1,3-oxathiolane-2-thione, was carried out with TfOH or TfOMe as an initiator in PhCl at rt – 60 °C. The molecular weight distribution (Mw/Mn) of the polymer obtained with TfOMe was very narrow even at 60 °C (Mw/Mn 1.14), and the Mn value of the polymers estimated by GPC was in good agreement with the molecular weight determined from ¹H-NMR. The living nature of the polymerization was confirmed by the conversion dependence of the Mn (Mw/Mn) and the correlation of the experimental and theoretical Mn (Mw/Mn) values.