Michelle Coote

Computer Aided Chemical Design

JACs Image Challenge

Sep 2012

Gryn'ova G., Ingold K.U., Coote M.L., New Insights into the Mechanism of Amine/Nitroxide Cycling during the Hindered Amine Light Stabilizer Inhibited Oxidative Degradation of Polymers J. Am. Chem. Soc., (2012), 134, 12979-12988. http://dx.doi.org/10.1021/ja3006379

Hindered amine light stabilizers (HALSs) are generally N-substituted tetramethylpiperidine-based radical-trapping antioxidants that are widely used to protect polymers from oxidative damage. The figure shows model alkoxyamines, formed from commercially available HALSs during the degradation of various substrates (R1-R3), and the corresponding free energies of N-O and O-bond homolyses. In which system(s) should formation of the secondary piperidines be expected?

(A) R1 and R2

(B) R2 only

(C) R1 and R3

(D) R3 only

Check your answer here!