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Revealing Model Dependencies in “Assessing the RAFT Equilibrium Constant via Model Systems: An EPR Study”
Author(s) -
Junkers Tanja,
BarnerKowollik Christopher,
Coote Michelle L.
Publication year - 2011
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.201100494
Subject(s) - raft , radical , equilibrium constant , reaction rate constant , thermodynamics , chemistry , constant (computer programming) , electron paramagnetic resonance , quantum , chain transfer , fragmentation (computing) , computational chemistry , physics , polymer , radical polymerization , kinetics , quantum mechanics , computer science , organic chemistry , polymerization , programming language , operating system
In a recent article (W. Meiser, M. Buback, Assessing the RAFT Equilibrium Constant via Model Systems: An EPR Study, Macromol. Rapid Commun. 2011 , 18, 1490‐1494), it is claimed that evidence is found that unequivocally proves that quantum mechanical calculations assessing the equilibrium constant and fragmentation rate coefficients in dithiobenzoate‐mediated reversible addition fragmentation transfer (RAFT) systems are beset with a considerable uncertainty. In the present work, we show that these claims made by Meiser and Buback are beset with a model dependency, as a critical key parameter in their data analysis – the addition rate coefficient of the radicals attacking the C=S double bond in the dithiobenzoate – induces a model insensitivity into the data analysis. Contrary to the claims made by Meiser and Buback, their experimental results can be brought into agreement with the quantum chemical calculations if a lower addition rate coefficient of cyanoisopropyl radicals (CIP) to the CIP dithiobenzoate (CPDB) is assumed. To resolve the model dependency, the addition rate coefficient of CIP radicals to CPDB needs to be determined as a matter of priority.