近日，浙江大学伍广朋团队报道了有机碱催化β-丙内酯开环聚合的机理洞察：烷基-氧键断裂的证据。相关论文于2026年10月28日发表在《中国高分子科学杂志》上。

可生物降解脂肪族聚酯是传统塑料极具潜力的替代材料，这类聚酯可通过相应内酯的开环聚合（ROP）制备。四元环 β- 丙内酯（BPL）的开环聚合是合成聚 (3 - 羟基丙酸酯)（一类聚羟基烷酸酯材料）的高效途径。目前已有大量有机催化体系（包括有机碱催化体系）被开发，用以实现高效聚合并获得高分子量产物，但 β- 丙内酯的开环机理及其相关实验证据仍不明确。

具体而言，针对有机碱 / 醇体系催化的 β- 丙内酯开环聚合，仍需更多实验证据来确定亲核进攻位点：进攻羰基碳会造成单体酰氧键断裂，而进攻 β 碳则引发烷氧键断裂。迄今为止，该体系的主导反应路径尚未得到明确证实。

研究组以有机碱 / 醇为催化体系，提出一种利用苄溴淬灭聚合反应来区分 β- 丙内酯开环路径的实验方案。实验结果表明，有机碱优先夺取 β- 丙内酯的 α 质子，生成丙烯酸根阴离子作为实际引发种；β- 丙内酯开环聚合遵循烷基断裂机理，即丙烯酸根引发剂进攻 β- 丙内酯的 β 碳。该研究可为后续 β- 丙内酯开环聚合催化剂的理性设计提供支撑。

附：英文原文

Title: Mechanistic Insights into Ring-opening Polymerization of β-Propiolactone Catalyzed by Organic Bases: Evidence for Alkyl-cleavage

Author: Rui Yan, Chu-Han Deng, Yan-Jun Liu, Shuai-Shuai Zhao, Zong-Min Wu, Xiao-Mei Song, Guang-Peng Wu

Issue&Volume: 2026-10-28

Abstract: Biodegradable aliphatic polyesters are promising alternatives to conventional plastics, which can be synthesized by the ring-opening polymerization (ROP) of the corresponding lactones. ROP of four-membered β-propiolactone (BPL) provides an efficient approach to poly(3-hydroxypropionate), a class of polyhydroxyalkanoate materials. Although numerous organocatalytic systems, including those based on organic bases, have been exploited to achieve high efficiency and high molecular weights, the ring-opening mechanism of BPL and associated experimental evidence remain unclear. Specifically, for the ring-opening polymerization of BPL catalyzed by organic base/alcohol systems, further experimental evidence is required to elucidate the site that undergoes nucleophilic attack: attack at the carbonyl carbon versus the β-carbon of BPL results in acyl-oxygen cleavage and alkyl-oxygen cleavage of the monomer, respectively. The dominant reaction pathway for this system has not been definitively confirmed to date. In this work, using organic bases/alcohol as the catalytic system, we propose an experimental strategy to distinguish the ring-opening pathway of BPL by quenching the polymerization with benzyl bromide. The results illustrated that organic bases preferentially abstracted the α-proton of BPL, generating an acrylate anion as the actual initiator. The ROP of BPL is processed via an alkyl-cleavage mechanism, in which the acrylate initiator attacks the β-carbon of BPL. This research will facilitate the rational design of catalysts for the ROP of BPL in the future.

DOI: 10.1007/s10118-026-3892-2

Source:https://www.cjps.org/en/article/doi/10.1007/s10118-026-3892-2/