The kinetics of addition and fragmentation in reversible addition fragmentation chain transfer polymerization: An ab initio study.

摘要: High-level ab initio calculations of the forward and reverse rate coefficients have been performed for a series prototypical reversible addition fragmentation chain transfer (RAFT) reactions:  R• + SC(Z)SCH3 → RSC•(Z)SCH3, R = CH3, with Z Ph, CH2Ph; (CH3), CH2COOCH3, CH2Ph, C(CH3)2CN. The reactions are fast (ca. 106−108 L mol-1 s-1), typically around three orders magnitude faster than to CC bonds alkenes. much more sensitive nature substituents vary from 10-4 107 s-1. In both directions, qualitative effects on largely follow those equilibrium constants reactions, being favored by bulky radical-stabilizing R-groups Z-groups. However, there is evidence additional polar hydrogen-bonding interactions in transition structures so...