Thermodynamic Components of the Atom Transfer Radical Polymerization Equilibrium: Quantifying Solvent Effects
Thermodynamic Components of the Atom Transfer Radical Polymerization Equilibrium: Quantifying Solvent Effects
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DOI：
10.1021/ma901094s
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发表时间：
2009-09-08
期刊：
影响因子：
5.5
通讯作者：
Matyjaszewski, Krzysztof
中科院分区：
文献类型：
--
作者：
Braunecker, Wade A.;Tsarevsky, Nicolay V.;Matyjaszewski, Krzysztof
一个热力学方案表示的原子转移自由基聚合（ATRP）平衡的正式总和涉及碳-卤素键均裂和三个额外的不同的热力学贡献的催化剂的平衡进行严格的评价。测量金属络合物和卤素原子两者的还原/氧化，以及催化剂的较高氧化态对卤素阴离子的亲和力（或“亲卤性”）。通过独立测量、计算或计算一种催化剂/烷基卤化物组合在乙腈中的总体ATRP平衡常数和所有四个贡献平衡常数来验证模型的有效性和自洽性。作为一个彻底的证明的价值和有效性的计划，不同的平衡常数的测量或计算在11个不同的有机溶剂。并且它们的值的比较用于理解和预测ATRP中的催化剂活性，具有高精度。该方案很好地解释了，例如，狡猾的ATRP平衡常数在二甲基亚砜中比在丙酮中大的一个因素，以及为什么在乙腈和三种不同的醇中几乎相同。的溶剂效应也是约80，定量分析的Karnlet-Taft参数，和线性溶剂化能的关系，外推催化剂活性超过7个数量级，在17个以上的有机溶剂和水。
A thermodynamic scheme representing the atom transfer radical polymerization (ATRP) equilibrium as the formal sum of equilibria involving carbon-halogen bond homolysis and three additional distinct thermodynamic contributions related to the catalyst is rigorously evaluated. The reduction/oxidation of both the metal complex and the halogen atom, and the affinity of the higher oxidation state of the catalyst for halide anions (or "halidophilicity"), are measured. The validity and self-consistency of the model are verified by independently measuring, computing, or calculating the overall ATRP equilibrium constant and all four contributing equilibrium constants for one catalyst/alkyl halide combination in acetonitrile. As a thorough demonstration of the value and effectiveness of the scheme, the different equilibrium constants were measured or calculated in I I different organic solvents. and a comparison of their values was used to both understand and predict catalyst activity in ATRP with high accuracy. The scheme explains quite well, for example, wily the ATRP equilibrium constant is greater in dimethyl sulfoxide than in acetone by a factor of and why in acetonitrile and three different alcohols it is nearly identical. The solvent effects are also about 80, quantitatively analyzed in terms of Karnlet-Taft parameters, and linear solvation energy relationships are employed to extrapolate catalyst activity over 7 orders of magnitude in 17 more organic solvents and water.