37999-09-0Relevant articles and documents
Effect of [PMDETA]/[Cu(I)] ratio, monomer, solvent, counterion, ligand, and alkyl bromide on the activation rate constants in atom transfer radical polymerization
Nanda, Ajaya Kumar,Matyjaszewski, Krzysztof
, p. 1487 - 1493 (2003)
A detailed study on the effect of [PMDETA]/[Cu(I)] ratio, monomer, solvent polarity, counterion, ligand, and alkyl bromide on the activation rate constant (kact) in ATRP was carried out. The highest values of kact for Cu(I)Br were obtained at [PMDETA]/[Cu(I)Br] ～ 1/1 in more polar solvents and ascribed to a neutral [Cu(PMDETA)Br] structure of the complex. However, in less polar solvent mixtures a relatively fast reaction was observed already at the 0.5/1 ratio with the smaller rate increase up to [PMDETA]/[Cu(I)Br] ～ 1/1. The highest values of kact for Cu(I)PF6 were observed at [PMDETA]/[Cu(I-Br] ～ 1/1 in more polar, less polar solvent mixtures and monomer, which was explained by the formation of an ionic [Cu(PMDETA)]+PF6- complex. In both more polar and less polar media, the values of kact. were slightely larger for PF6- than Br- counterion. However, in methyl acrylate, kactwas 1.9 times larger for Br- than PF6- counterion. This was attributed to monomer coordination through the open coordination site of an ionic [Cu(PMDETA)]+ Y- (Y = PF6/BPh4) complex, which reduced complex activity. The values of kact were higher for PMDETA containing three nitrogen atoms as compared to the ligand containing two nitrogen atoms and one oxygen atom (BDMAEE). The relative rates of kact of the alkyl bromides follow the order EBriB (30) ? MBrP (3) > t-BBrP (1). In the absence of monomer, the values of the kact for different ligand/counterion follow the order PMDETA/PF6- > PMDETA/Br- > BDMAEE/Br- > bpy/ PF6- > bpy/Br-.
Understanding atom transfer radical polymerization: Effect of ligand and initiator structures on the equilibrium constants
Tang, Wei,Kwak, Yungwan,Braunecker, Wade,Tsarevsky, Nicolay V.,Coote, Michelle L.,Matyjaszewski, Krzysztof
scheme or table, p. 10702 - 10713 (2009/02/05)
Equilibrium constants in Cu-based atom transfer radical polymerization (ATRP) were determined for a wide range of ligands and initiators in acetonitrile at 22°C. The ATRP equilibrium constants obtained vary over 7 orders of magnitude and strongly depend o
Electron Spin Resonance Study of Monomeric, Dimeric, and Polymeric Acrylate Radicals Prepared Using the Atom Transfer Radical Polymerization Technique - Direct Detection of Penultimate-Unit Effects
Kajiwara, Atsushi,Nanda, Ajaya Kumar,Matyjaszewski, Krzysztof
, p. 1378 - 1385 (2007/10/03)
Model radicals generated through the reaction of organotin compounds with radical precursors prepared by atom transfer radical addition (ATRA) or atom transfer radical polymerization (ATRP) were studied by electron spin resonance (ESR). Dimers of various (meth)acrylate units, methyl acrylate (MA), tert-butyl acrylate (tBA), and methyl methacrylate (MMA), MA-MA-Br, MA-tBA-Br, tBA-tBA-Br, MMA-tBA-Br, and MA-MMA-Br, were prepared by ATRA. These dimers provided radicals mimicking the active species in a radical copolymerization of MA, MMA, and tBA. Well-resolved ESR spectra of the dimeric radicals confirm electronic and steric effects of the penultimate unit on the propagating radical. Hyperfine splitting constants observed for monomeric, dimeric, oligomeric, and polymeric tert-butyl acrylate radicals depend on the polymer chain length. The variation of ESR spectra with the chain length and penultimate unit was compared with the rate constants of activation in an ATRP using a CuBr/bpy catalyst system.
Determination of Rate Constants for the Activation Step in Atom Transfer Radical Polymerization Using the Stopped-Flow Technique
Pintauer, Tomislav,Braunecker, Wade,Collange, Edmond,Poli, Rinaldo,Matyjaszewski, Krzysztof
, p. 2679 - 2682 (2007/10/03)
The use of stopped-flow techniques to measure activation rate constants for model systems in copper-mediated atom transfer radical polymerization (ATRP) was studied. The structures of model alkyl halides and complexing ligands used in conjunction with CuB
Rate Constants for Halogen Atom Transfer from Representative α-Halocarbonyl Compounds to Primary Alkyl Radicals
Curran, Dennis P.,Bosch, Eric,Kaplan, Jere,Newcomb, Martin
, p. 1826 - 1831 (2007/10/02)
Rate constants for halogen atom transfer from diethyl methyliodomalonate (7a), iodoacetonitrile (7b), ethyl 2-methyl-2-iodopropanoate (7c), ethyl iodoacetate (7d), diethyl methylbromomalonate (7e), and ethyl bromoacetate (7f) to simple primary alkyl radicals have been studied by a variety of competition reactions.The Arrhenius functions for halogen atom transfer to the undecyl radical from halides 7d and 7f are log (kI, M-1 s-1) = 10.4 - 4.4/θ and log (kBr, M-1 s-1) = 10.4 - 8.2/θ, respectively.The rate constants for halogen atom transfer to a primaryradical from the series of compounds 7a-7f at 50 deg C are 1.8 x 109, 1.7 x 109, ca. 6 x 108, 2.6 x 107, 1.0 x 106, and 7.0 x 104 M-1 s-1, respectively.The kinetic values are useful for the planning of synthetic methods that incorporate an atom transfer-cyclization process.
