No abstract

The inhibitory regulation mechanism towards the methyl 2‐methylpropionate radical (a model of the poly(methyl methacrylate) [MMA] propagation radical) by naphthoquinone derivatives in radical polymerization in an aerobic or anaerobic atmosphere has been studied experimentally by liquid chromatography, mass spectrometry, and nuclear magnetic resonance (NMR) measurements of the isolated reaction products, which were purified by preparative thin‐layer chromatography. In addition, we have carried out a theoretical analysis (DFT B3LYP/6‐311+G**) of the frontier orbital interactions and reaction Gibbs free energies (ΔG) for the formation of the relevant reaction products and intermediates and activation free energies (ΔG#) and frontier electron densities (fA(R)) of the radical reactions. Consequently, the reaction mechanism where quinone products are formed by the attack of propagation radicals at the C2 carbon next to the carbonyl group in naphthoquinone was rationalized.