Ring-opening reaction of 5-membered cyclic ammonium salt groups at the end of poly(tetrahydrofuran)

• Published in: Reactive & functional polymers Vol. 37; no. 1; pp. 57 - 63
• Main Authors: Oike, Hideaki, Hatano, Hiroshi, Tezuka, Yasuyuki
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.1998
• Subjects: 1-Methyl pyrrolidinium salt; p K a; Ring-opening reaction; Substituted benzoate anion; Telechelics; Ring-opening reaction; p K a; Substituted benzoate anion; 1-Methyl pyrrolidinium salt; Telechelics
• ISSN: 1381-5148
• DOI: 10.1016/S1381-5148(97)00119-3

The ring-opening reaction of 1-methylpyrrolidinium salt groups located at the end of poly(tetrahydrofuran) (poly(THF)) segment was studied with a series of p-substituted benzoate, having either methoxy, methyl, chloro or nitro substituent as a counter-anion. At 100°C, such p-substituted benzoate anions as having an electron-donating methoxy or methyl substituent caused a ring-opening reaction of pyrrolidinium salt end groups, while others having an electron-withdrawing chloro or nitro substituent were poorly reactive to undergo the ring-opening of the end groups. Accordingly, the pathway of this nucleophilic reaction is primarily governed by the basicity, i.e., p K a of the corresponding p-substituted benzoic acid. At 120°C, on the other hand, the nucleophilic substitution reaction at the N-methyl position of the pyrrolidinium salt end groups occurred predominantly.