Tang Wei, Kwak Yungwan, Braunecker Wade, Tsarevsky Nicolay V, Coote Michelle L, Matyjaszewski Krzysztof
Center for Macromolecular Engineering, Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, Pennsylvania 15213, USA.
J Am Chem Soc. 2008 Aug 13;130(32):10702-13. doi: 10.1021/ja802290a. Epub 2008 Jul 19.
Equilibrium constants in Cu-based atom transfer radical polymerization (ATRP) were determined for a wide range of ligands and initiators in acetonitrile at 22 degrees C. The ATRP equilibrium constants obtained vary over 7 orders of magnitude and strongly depend on the ligand and initiator structures. The activities of the Cu(I)/ligand complexes are highest for tetradentate ligands, lower for tridentate ligands, and lowest for bidentate ligands. Complexes with tripodal and bridged ligands (Me6TREN and bridged cyclam) tend to be more active than those with the corresponding linear ligands. The equilibrium constants are largest for tertiary alkyl halides and smallest for primary alkyl halides. The activities of alkyl bromides are several times larger than those of the analogous alkyl chlorides. The equilibrium constants are largest for the nitrile derivatives, followed by those for the benzyl derivatives and the corresponding esters. Other equilibrium constants that are not readily measurable were extrapolated from the values for the reference ligands and initiators. Excellent correlations of the equilibrium constants with the Cu(II/I) redox potentials and the carbon-halogen bond dissociation energies were observed.
在22摄氏度的乙腈中，针对多种配体和引发剂测定了铜基原子转移自由基聚合（ATRP）中的平衡常数。所获得的ATRP平衡常数变化范围超过7个数量级，并且强烈依赖于配体和引发剂的结构。对于四齿配体，Cu(I)/配体络合物的活性最高；对于三齿配体，活性较低；对于双齿配体，活性最低。具有三脚架型和桥连配体（Me6TREN和桥连环胺）的络合物往往比具有相应线性配体的络合物更具活性。对于叔烷基卤化物，平衡常数最大；对于伯烷基卤化物，平衡常数最小。烷基溴化物的活性比相应的烷基氯化物大几倍。对于腈衍生物，平衡常数最大，其次是苄基衍生物和相应的酯。其他不易测量的平衡常数是从参考配体和引发剂的值外推得到的。观察到平衡常数与Cu(II/I)氧化还原电位和碳 - 卤键解离能之间具有良好的相关性。
