2348-51-8Relevant academic research and scientific papers
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 (2004)
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
Magnetic Field and Isotope Dependence of the Reaction Rates of Micellized Triplet Radical Pairs
Turro, Nicholas J.,Zimmt, Matthew B.,Gould, Ian R.
, p. 433 - 437 (1988)
Nanosecond time resolved optical absorption studies of the isotopic dependence of the magnetic field effect on geminate triplet benzylic radical pair reaction dynamics in micelles of HDTCl are reported.The isotopic susceptibilities of the T+/-
Light-active azaphenalene alkoxyamines: Fast and efficient mediators of a photo-induced persistent radical effect
Bottle, Steven E.,Clement, Jean-Louis,Fleige, Mirco,Simpson, Emily M.,Guillaneuf, Yohann,Fairfull-Smith, Kathryn E.,Gigmes, Didier,Blinco, James P.
, p. 80328 - 80333 (2017/04/04)
Here we report the first example of an alkoxyamine derived from an azaphenalene nitroxide, which when exposed to UV-light, readily undergoes homolysis to efficiently and cleanly re-form a nitroxide. This process selectively cleaves the C-O bond of the alkoxyamine and occurs orders of magnitude more rapidly than any other alkoxyamine homolysis previously described in the literature. We demonstrate the use of light to generate a persistent radical effect (PRE) and apply this to undertake radical insertion, radical exchange and proof of concept polymerization reactions.
Monomer- and polymer radicals of vinyl compounds: EPR and DFT studies of geometric and electronic structures in the adsorbed state
Lund, Anders,Danilczuk, Marek
, p. 367 - 377,11 (2012/12/12)
Electron paramagnetic resonance (EPR) spectroscopy was applied to study the paramagnetic species formed from styrene, 1,1-diphenylethylene, α-methylstyrene, β-methylstyrene and methylmethacrylate adsorbed on amorphous silica gel after γ-irradiation at 77
Alkyl group dissociation during corona excitation of alkylbenzenes
Yoon, Young Wook,Lee, Sang Kuk
experimental part, p. 741 - 745 (2012/01/03)
Well-resolved vibronic emission spectra were recorded in the visible region from the corona discharge of precursor alkylbenzenes in a technique of corona excited supersonic expansion using a pinhole-type glass nozzle. From the observed spectra, we found t
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
Spectroscopic evidence of α-methylbenzyl radical in the gas phase
Lee, Gi Woo,Ahn, Hyeon Geun,Kim, Tae Kyu,Lee, Sang Kuk
experimental part, p. 193 - 196 (2009/05/15)
We report the observation of the spectroscopic evidence of the α-methylbenzyl radical in a corona excited supersonic expansion using a pinhole-type glass nozzle for the first time. The precursors, toluene, ethylbenzene, and isopropylbenzene, seeded in a l
Steric and polar effects of the cyclic nitroxyl fragment on the C-ON bond homolysis rate constant
Fischer, Hanns,Kramer, Andreas,Marque, Sylvain R. A.,Nesvadba, Peter
, p. 9974 - 9984 (2008/02/01)
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.
EPR investigation of persistent radicals produced from the photolysis of dibenzyl ketones adsorbed on ZSM-5 zeolites
Turro, Nicholas J.,Lei, Xue-Gong,Jockusch, Steffen,Li, Wei,Liu, Zhiqiang,Abrams, Lloyd,Ottaviani, M. Francesca
, p. 2606 - 2618 (2007/10/03)
Photolysis of ketones (1, 1-oMe, 2, 2-oMe, 3, and 4) adsorbed on ZSM-5 zeolites produces persistent carbon-centered radicals that can be readily observed by conventional steady-state EPR spectroscopy. The radicals are persistent for time periods of seconds to many hours depending on the supramolecular structure of the initial radical@zeolite complex and the diffusion and reaction dynamics of radicals produced by photolysis. The structures of the persistent radicals responsible for the observed EPR spectra are determined by a combination of alternate methods of generation of the same radical, by deuterium substitution, and by spectral simulation. A clear requirement for persistence is that the radicals produced by photolysis must either separate and diffuse from the external to the internal surface or be generated within the internal surface and separate and diffuse apart. The persistence of radicals located on the internal surface is the result of inhibition of radical-radical reactions. Radicals that are produced on the external surface and whose molecular structure prevents diffusion into the internal surface are transient because radical-radical reactions occur rapidly on the external surface. The reactions of the persistent radicals with oxygen and nitric oxide were directly studied in situ by EPR analysis. In the case of reaction with oxygen, persistent peroxy radicals are formed in high yield. The addition of nitric oxide scavenges persistent radicals and leads initially to a diamagnetic nitroso compound, which is transformed into a persistent nitroxide radical by further photolysis. The influence of variation of radical structure on transience/persistence is discussed and correlated with supramolecular structure and reactivity of the radicals and their parent ketones.
Supramolecular effects on the dynamics of radicals in MFI zeolites: A direct EPR investigation
Turro, Nicholas J.,Jockusch, Steffen,Lei, Xue-Gong
, p. 5779 - 5782 (2007/10/03)
Photolysis of the supramolecular complexes (dibenzyl ketones@ZSM-5) produced supramolecular complexes of benzyl radicals@ZSM-5, which were directly detected by CW-EPR spectroscopy, and provided information on the dynamics of the radicals. The lifetimes of
