Propagation chains with 1,2 and 2,1 last-inserted monomer unit in 1-hexene polymerization with MgCl₂-supported Ziegler-Natta catalysts were quench-labeled by thiophene-2-carbonyl chloride, and the two kinds of 2-thenoyl-labeled chain ends were determined by ¹H NMR analysis. The number of labeled chains was noticeably smaller than the number of dead chains formed by chain transfer with alkylaluminum cocatalyst, and grew with time more slowly than the latter, showing that side reactions between the quencher and Al-polymeryl moieties are negligible. The active sites with 2,1 last-inserted monomer were halted in dormant state, which lead to their gradual accumulation in the 30 s polymerization process. The catalyst containing phthalate type internal donor has higher percentage of dormant sites as compared with the catalyst containing diol ester. The combination of acyl chloride quench-labeling and ¹H NMR analysis forms a reliable and easily accessible method of tracing and characterizing active sites in transition metal catalyzed olefin polymerization.

在1-己烯与MgCl ₂负载的Ziegler-Natta催化剂中1-己烯聚合中，最后插入1,2和2,1单体单元的传输链被噻吩-2-羰基氯和两种2-thenoyl-标记的链端由¹确定1 H NMR分析。标记链的数量明显少于通过烷基铝助催化剂进行链转移而形成的死链的数量，并且随着时间的增长比后者更慢，这表明淬灭剂和Al-聚合基之间的副反应可以忽略不计。具有2,1最后插入单体的活性位点处于休眠状态，这导致它们在30 s聚合过程中逐渐积累。与含有二醇酯的催化剂相比，含有邻苯二甲酸酯型内部给体的催化剂具有更高的休眠位点百分比。酰氯淬灭标记和¹ H NMR分析相结合，形成了一种可靠且易于使用的追踪和表征过渡金属催化的烯烃聚合反应中活性位点的方法。