Thermal decomposition of four tertiary N-(2-methylpropyl)-N-(1-diethylphosphono-2,2-dimethylpropyl)-N-oxyl (SG1)-based alkoxyamines (SG1-C(Me)2-C(O)-OR, R = Me, tBu, Et, H) has been studied at different experimental conditions using 1H and 31P NMR spectroscopies. This experiment represents the initiating step of methyl methacrylate polymerization. It has been shown that H-transfer reaction occurs during the decomposition of three alkoxyamines in highly degassed solution, whereas no products of H-transfer are detected during decomposition of SG1-MAMA alkoxyamine. The value of the rate constant of H-transfer for alkoxyamines 1 (SG1-C(Me)2-C(O)-OMe) and 2 (SG1-C(Me)2-C(O)-OtBu) has been estimated as 1.7 × 103 M−1s−1. The high influence of oxygen on decomposition mechanism is found. In particular, in poorly degassed solutions, nearly quantitative formation of oxidation product has been observed, whereas at residual pressure of 10−5 mbar, the main products originate from H-atom transfer reaction. The acidity of the reaction medium affects the decomposition mechanism suppressing the H-atom transfer. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013
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