Assessing the RAFT equilibrium constant via model systems: an EPR study.
Assessing the RAFT equilibrium constant via model systems: an EPR study.
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DOI：
10.1002/marc.201100228
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发表时间：
2011-09
影响因子：
4.6
通讯作者：
W. Meiser;M. Buback
中科院分区：
文献类型：
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作者：
W. Meiser;M. Buback
利用电子顺磁共振（EPR）谱法推导了二硫代苯甲酸氰基异丙酯（CPDB）-氰基异丙基自由基（CIP）模型体系的可逆加成-断裂链转移（RAFT）平衡常数K（eq）。CIP物质由偶氮二异丁腈（AIBN）热分解产生。在70 °C甲苯溶液中，K（eq）=（9 ± 1）L · mol（-1）。在60 ° C至100 °C之间测量K（eq）= k（ad）/k（β），得到ΔE（a）=（-28 ± 4）kJ · mol（-1），即k（ad）和k（β）的活化能之差。在模型系统上测量的数据指示通过向CPDB添加CIP产生的中间自由基的快速碎裂。
Reversible addition-fragmentation chain transfer (RAFT) equilibrium constants, K(eq), for the model system cyano-iso-propyl dithiobenzoate (CPDB) - cyano-iso-propyl radical (CIP) have been deduced via electron paramagnetic resonance (EPR) spectroscopy. The CIP species is produced by thermal decomposition of azobis-iso-butyronitrile (AIBN). In solution of toluene at 70 °C, K(eq) has been determined to be (9 ± 1) L · mol(-1). Measurement of K(eq) = k(ad)/k(β) between 60 and 100 °C yields ΔE(a) = (-28 ± 4) kJ · mol(-1) as the difference in the activation energies of k(ad) and k(β). The data measured on the model system are indicative of fast fragmentation of the intermediate radical produced by addition of CIP to CPDB.