Examination of novel alkoxyamines has demonstrated the pivotal role that the nitroxide plays in mediating the “living” or controlled polymerization of a wide range of vinyl monomers. Surveying a variety of different alkoxyamine structures led to α-hydrido derivatives based on a 2,2,5-trimethyl-4-phenyl-3-azahexane-3-oxy, 1, skeleton which were able to control the polymerization of styrene, acrylate, acrylamide, and acrylonitrile based monomers. For each monomer set, the molecular weight could be controlled from 1000 to 200 000 amu with polydispersities typically 1.05−1.15. Block and random copolymers based on combinations of the above monomers could also be prepared with similar control. In comparison with 2,2,6,6-tetramethylpiperidinoxy (TEMPO), these new systems represent a dramatic increase in the range of monomers that can be polymerized under controlled conditions and overcome many of the limitations associated with nitroxide-mediated “living” free radical procedures. Monomer selection and functional group compatibility now approach those of ATRP-based systems.

No abstract

No abstract

No abstract

Novel syntheses of cyclopropyldiisopropylamine (15), di-tert-butylcyclopropylamine (16), dicyclopropylisopropylamine (17), and tricyclopropylamine (18) are described. Hyperfine data were determined by ESR spectroscopy for the radical cations of these trialkylamines, as well as for those of ethyldiisopropylamine (10), diisopropyl-n-propylamine (11), dicyclohexylethylamine (12), diisopropyl-3-pentylamine (14), and 1-azabicyclo[3.3.3]undecane (manxine; 27). The radical cation of triisopropylamine (13) was reexamined under conditions of improved spectral resolution. Coupling constants of the 14N nucleus and the β-protons in the radical cations of 18 trialkylamines provide reliable information about the geometries of these species, which are confirmed by theoretical calculations. With the exception of a few oligocyclic amines, for which flattening is impaired by the rigid molecular framework, all of the radical cations should be planar. Correlation between the observed coupling constants of the β-protons and the calculated values of the dihedral angle θ, defining the conformation of the alkyl substituent or the azacycloalkane, is verified. Upon oxidation, striking changes occur for those amines that have cyclopropyl substituents, because of the tendency of these groups to assume a perpendicular conformation in the neutral amines and a bisected orientation in the corresponding radical cations.