Free Radical Initiation Mechanisms in the Polymerization of Methyl Methacrylate and Styrene with 1,1,3,3-Tetramethylbutyl Peroxypivalate: Addition of Neopentyl Radicals
作者:Tomoyuki Nakamura、W. Ken Busfield、Ian D. Jenkins、Ezio Rizzardo、San H. Thang、Shuji Suyama
DOI:10.1021/ja972240t
日期:1997.11.1
to form neopentyl radicals (14b) and a 1,5-H shift to form 4-hydroxy-2,2,4-trimethylpentyl radicals (14c), were observed in both monomer systems. The resulting alkyl radicals underwent selective addition to the two monomers. The relative reactivities of the alkyl radicals toward addition to the monomers were obtained from competitive addition/trapping reactions. The absolute rate constants for the addition
在自由基清除剂 1,1,3,3-四甲基-2,3 存在下,1,1,3,3-四甲基丁基(叔辛基)过氧新戊酸酯 (1) 与甲基丙烯酸甲酯 (MMA) 和苯乙烯的反应-dihydro-1H-isoindol-2-yloxyl (2) 已在 60 °C 下进行了研究。叔丁基和叔辛氧基自由基 (3) 由 1 的热解产生。 3 的主要单分子反应,即 β 断裂形成新戊基自由基 (14b) 和 1,5-H 转移形成 4 -羟基-2,2,4-三甲基戊基(14c),在两种单体系统中都观察到。所得烷基自由基选择性地加成到两种单体中。烷基自由基对单体加成的相对反应性是从竞争性加成/捕集反应中获得的。在 60 °C 下将烷基 14b 和 14c 添加到两种单体的绝对速率常数估计为 9.5 × 105 和 2.6 × 105 M-1 s-1 到 MMA 和 4.5 × 105 和 0.7 × 105 M- 1 s-1 分别为苯乙烯。3