Studies on controlled radical polymerisation using 5-membered cyclic PROXYL nitroxides and corresponding alkoxyamines

Abstract

Scheme 1. Equilibrium between dormant and active species in TEMPO-mediated CRP.

Homolysis and Decomposition of Alkoxyamines Containing PROXYL and TEMPO Residues: A Comparison

“…Compound 4 was synthesized according to a similar procedure; 1 to 3 were prepared from styrene, nitroxide and DTBPO according to a literature procedure 24. In all cases, characterisation data were in accord with literature values.…”

“…Previously, we have studied24–26 NMP involving PROXYL nitroxides, which are the 5‐membered ring analogues of TEMPO. We chose to study these initially because their functionalization, particularly adjacent to the ring N atom, is more accessible synthetically than that of TEMPO.…”

“…We chose to study these initially because their functionalization, particularly adjacent to the ring N atom, is more accessible synthetically than that of TEMPO. Quantitative comparison indicated that a PROXYL derivative bearing an α ‐Ph substituent was found to mediate styrene polymerisation at around 2.5 times the rate of TEMPO with no loss of control 24. More recently, it has been shown that the same mediator can bring about the living (but not controlled) polymerisation of butyl acrylate, which cannot be achieved with TEMPO 25,26.…”

Long‐range polar and steric effects in propionate‐SG1‐type alkoxyamines (SG1‐CHMeCOOX): a multiparameter analysis

“…17,18 We 15,17,[19][20][21][22] and others 11,[23][24][25][26][27][28][29] have shown that the C-ON bond of alkoxyamines was either strengthened by anomeric 26,29 (heteroatom bonded to the carbon) and polar 11,22,26,28,29 (electron withdrawing groups (EWG) bonded to the nitrogen atom) effects or weakened by the stabilization 11,17,21,23,24,26,29 of the released alkyl and nitroxyl 29 (intramolecular hydrogen bond IHB) radicals, and by the steric strain and polar effects of both alkyl and nitroxyl fragments. 11,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]…”

2-tert-Butoxy-1-phenyl-1-(2,2,6,6-tetramethylpiperidin-1-yloxy)ethane

“…Synthetic routes to alkoxyamines include the trapping of alkyl radicals by free nitroxides at moderate temperatures (Braslau et al, 1997;Miura et al, 1998) and a catalytic route involving Mn-salen complexes [H 2 salen is bis(salicylidene)ethylenediamine; Dao et al, 1998]. The title compound, (I), has been synthesized in the course of these studies (Cameron et al, 2000).…”