Substituent effect on the cationic ring‐opening polymerization of acyloxymethyl five‐member cyclic dithiocarbonates

Abstract

Five-member cyclic dithiocarbonates were synthesized by the reactions of carbon disulfide with benzoic, p-anisic, p-chlorobenzoic, 1-naphthalenecarboxylic, pnitrobenzoic, and p-(tert-butyl)benzoic glycidyl esters, and their cationic ring-opening polymerizations were carried out with methyl trifluoromethane sulfonate and trifluoromethane sulfonic acid as initiators at room temperature to 80°C. Polymers with number-average molecular weights of 3400 -24,900 were obtained in high yields, and their structures were estimated by NMR and IR spectroscopy. The monomers showed a clear difference in the polymerization rate according to the substituents. The rate of polymerization decreased in the order of p-chlorobenzoic Ն benzoic Ͼ 1-naphthalenecarboxylic Ͼ p-nitro-benzoic Ͼ p-tert-butylbenzoic Ͼ p-anisic. The data of the reaction kinetics, NMR studies, and molecular orbital calculations proved a plausible mechanism involving the participation of p-substituted benzoyloxymethyl groups to stabilize the cationic propagating end. The polymers showed decomposition temperatures with 5% weight loss ranging from 200 to 260°C. No glass-transition temperatures for the polymers were observed below 200°C by differential scanning calorimetry.

Controlled Cationic Ring-Opening Polymerization of 1,3-Oxazolidine-2-thione Derived from l-Serine

“…In the IR spectra, the characteristic absorption of the thiocarbonyl in S L was observed at 1504 cm -1 , while that of carbonyl in poly S L was at 1658 cm -1 instead. These findings indicate that the cationic ring-opening polymerization proceeds through specific isomerization of the thiocarbonyl group into the carbonyl group, which is in same manners with the controlled polymerization of C(S)O monomers 2 …”

“…However, the polymers were obtained in lower yields and were not characterized sufficiently. Since we have developed controlled polymerizations of sulfur-containing cyclic monomers such as monothiocarbonate and dithiocarbonate, we assumed that the polymerization of this interesting monomer would also be controlled. One of the most commonly used aminoethanols that can be transformed to 1,3-oxazolidine-2-thiones, should be l -serine which is one of the 20 natural amino acids constructing proteins.…”

Thiocarbonyl chemistry in polymer science

“…However, their backbones varied slightly due to neighbouring group participation. 149 Demonstrated in Scheme 27 with 21e as an example, the oxygen of the ester side group can encourage ring-opening to form intermediate III . This intermediate was observable by NMR spectroscopy due to its stability and led to a living polymerization ( Đ < 1.2), due to its long lived nature.…”

“…143 and 144) 21a-d = high polymerization conversions with dispersities as low as Đ = 1.23; isomerisation to the cyclic thiocarbonate in the presence of other Lewis acids (ZnCl 2 , SnCl 4 , TfOH); greater polymer : cyclic thiocarbonate ratios were achieved with higher concentrations of Lewis acid (2% = 38 : 62; 20% = 82 : 18); reactivity followed 21b/c > 21a > 21d, reportedly due to electron donating ability of the R-group 21e-h undergo ring-opening through neighbouring group participation,141,[145][146][147][148][149] leading to living polymerizations and different polymer backbones to monomers 21a-d Cationic S-O isomerism 22a = P(OEt) 3 , 140-160 °C (ref. 142) 22a: depolymerization occurs at higher temperatures (179 °C) and longer reaction times (20 h versus 3 h); analogous O-analogue did not undergo polymerization under the same conditions 142 22b-e = TfOMe, 30 °C (ref.…”

Synthesis of a novel cyclic 5‐membered dithiocarbonate (DTC) having hydroxy group and its application to terminal functionalization of polyurethane

“…1,2 Additionally, DTC undergoes cationic ring-opening polymerization. 3,4 Besides these features of the reactivities, the straightforward and thus facile preparation method of this thio-containing compound also makes it attractive as a building block for polymer synthesis. DTC can be easily synthesized by the cycloaddition reaction of epoxide with carbon disulfide at ambient temperature.…”