Anionic Ring-Opening Polymerization of ε-Thionocaprolactone

Abstract

Anionic ring-opening polymerization of -thionocaprolactone was examined. When organolithiums, Grignard reagents, and lithium tert-butoxide were used as the initiators, the corresponding polythiocarboxylic-O-ester was selectively formed. When potassium tert-butoxide and 1,8-diazabicyclo-[5.4.0]undec-7-ene (DBU) were used, the corresponding polythiocarboxylic-S-ester was predominantly formed. The monomer conversion and M n of the obtained polymer increased with the polymerization temperature. Elongation of polymerization time resulted in decrease of the polymer yield and Mn. The polymerization in tetrahydrofuran (THF) proceeded faster compared with the polymerization in toluene. Formation of a cyclic dimer was observed in the polymerization in THF.

Controlled Organocatalytic Ring-Opening Polymerization of ε-Thionocaprolactone

“…This would only be true if 1 activates s -cis and s -trans esters equally. Indeed, DFT (B3LYP/6-31G**) calculations suggest that 1 is equally effective at the activation of (i.e., increasing the electophilicity of) 10 CL, tnCL, tCL, methyl thionoacetate, and methyl acetate. For these compounds, both the electrostatic charges at carbon (C═X) and polarity of the C═X bond increase by ~5–10% upon the binding of 1 (see Figure S15).…”

“…9,13,14 The anionic ROP of tnCL from alkyllithium reagents retains the S-carbonyl substitution, but reaction control suffers, and this method does not allow for M n control, copolymerization, or end group selection. 10 Partial inversion of substitution occurs with weak nucleophiles, resulting in a mixed polymer backbone. Polymerization conditions which result in inversion of S/O substitution are postulated to operate via an S N 2 propagation (Scheme 1).…”

Cationic ring-opening polymerization of ?-thionocaprolactone: Selective formation of polythioester

“…4 These spectroscopic data completely agreed with those of the polymer obtained by the anionic polymerization of ⑀-thionocaprolactone. 6 Table I summarizes the conditions and results of the BF 3 ⅐ OEt 2 -initiated polymerization of ⑀-thionocaprolactone. The corresponding poly- thioester was obtained in 75-88% yields irrespective of the solvents with the initial monomer concentration of 1 M at 28°C (runs 1-5).…”

“…We have recently reported the anionic ring-opening polymerization of ⑀-thionocaprolactone to afford the corresponding polythioester and/or polythionoester depending on the initiator. 6 Herein, we wish to report the first cationic ring-opening polymerization of ⑀-thionocaprolactone.…”

One-Pot Double Modification of Polymers Based on Thiolactone Chemistry

“…Aminolysis can thus be performed in aqueous medium, although hydrolysis is an important side reaction [92,108,109]. No reports of thiolysis of γ-thiolactones have been found so far, whereas thiolactones, having smaller and larger ring sizes, are susceptible to nucleophilic attack by a thiolate anion [108,[110][111][112].…”