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• 853886-36-9 2,2,7,7-tetramethyl-1-(1-phenylhex-5-enyloxy)[1,4]diazepane-5-one 

Relevant academic research and scientific papers

Tin-free radical alkoxyamine addition and isomerization reactions by using the persistent radical effect: Variation of the alkoxyamine structure

Various C-centered radicals can efficiently be generated through thermal C-O-bond homolysis of alkoxyamines. This method is used to perform environmentally benign radical cyclization and intermolecular addition reactions. These alkoxyamine isomerizations and intermolecular carboaminoxylations are mediated by the persistent radical effect (PRE). In the paper, the effect of the variation of the alkoxyamine structure - in particular steric effects in the nitroxide moiety - on the outcome of the PRE mediated radical reactions will be discussed. Fourteen different nitroxides were used in the studies. It will be shown that reaction times can be shortened about 100 times upon careful tuning of the alkoxyamine structure. Activation energies for the C-O-bond homolysis of the various alkoxyamines are provided. The kinetic data are used to explain the reaction outcome of the PRE-mediated processes.

Steric and polar effects of the cyclic nitroxyl fragment on the C-ON bond homolysis rate constant

Alkoxyamines and persistent nitroxyl radicals are important regulators of nitroxide mediated radical polymerization (NMP). Because polymerization times decrease with increasing rate constant of the homolysis of the C-ON bond between the polymer chain and the nitroxyl moiety, the factors influencing the cleavage rate constant are of considerable interest. Here, we present the measurements of the rate constants (kd) of the C-ON bond cleavage in new cyclic alkoxyamine models. The homolysis rate constants of 9 new alkoxyamines and 33 others given by the literature are analyzed with regards to the contributions of the polar inductive/field (σI) effect, the steric (E s) effect and the intramolecular hydrogen bonding (IHB) effect of the nitroxyl moieties, using the multiparameter equation established by Marque, i.e., log(kd/kd,0) = -3.07σI - 0.88E s - 5.88. Cyclic steric constants r(Ri) for seven- and eight-membered rings are developed. Analysis of the results provides new insight on the importance of the conformation of the alkoxyamine on the values of kd.