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

Bacon, Catherine A.; Cameron, Neil R.; Reid, Alistair

doi:10.1002/macp.200350074

Cited by 15 publications

(15 citation statements)

References 40 publications

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“…It can be assumed that the type of substituent in the isobutyrate‐2‐yl alkyl structure has no effect on the H‐atom transfer reaction. With TEMPOc 19 ( f D = 3.5%) and TEMPOb 17 ( f D = 2.2%), it was shown that the substituent on the ester group has no significant influence on the occurrence of the intermolecular H‐atom transfer reaction. Analyzing the experimental data for 10b and 10c , one can argue that 10b should also undergo the intermolecular H‐atom transfer reaction.…”

Section: Discussionmentioning

confidence: 99%

Kinetic study of H‐atom transfer in imidazoline‐, imidazolidine‐, and pyrrolidine‐based alkoxyamines: Consequences for nitroxide‐mediated polymerization

Edeleva

Kirilyuk

Zubenko

et al. 2009

J. Polym. Sci. A Polym. Chem.

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The H‐atom transfer reaction was studied for a series of imidazoline, imidazolidine, and pyrrolidine‐based alkoxyamines containing either isobutyrate‐2‐yl or 1‐phenylethyl alkyl fragments. The CO bond homolysis rate constants and activation energies were determined by 1H NMR product analysis as a function of temperature. Inter‐ and intramolecular H‐atom transfer reactions were distinguished by examination of alkoxyamine thermolysis products in the absence and in the presence of a radical scavenger (thiophenol or deuterated styrene). A correlation between the structure of the nitroxyl fragment of alkoxyamine and the H‐transfer reaction was found. The high steric demands of the substituents on the nitroxyl part of the isobutyrate‐2‐yl alkoxyamine decrease both types of reaction. For alkoxyamines containing the 1‐phenylethoxyamines, neither inter‐ nor intramolecular H‐atom transfer was observed. Controlled polymerization of methylmethacrylate initiated with imidazoline‐based alkoxyamine was observed, although the polymer obtained was not living. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6579–6595, 2009

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Section: Discussionmentioning

confidence: 99%

Kinetic study of H‐atom transfer in imidazoline‐, imidazolidine‐, and pyrrolidine‐based alkoxyamines: Consequences for nitroxide‐mediated polymerization

Edeleva

Kirilyuk

Zubenko

et al. 2009

J. Polym. Sci. A Polym. Chem.

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“…Second, the efficiency of this kind of nitroxide to control the polymerization of styrene has been previously established 14–17. The analysis of the H‐transfer reaction occurring for alkoxyamines presented in Chart leads to investigate the polymerization of methyl methacrylate with nitroxide 10 , which demonstrated the absence of hydrogen abstraction during its decomposition.…”

Section: Introductionmentioning

confidence: 99%

Application of cryobiopsy to morphological and immunohistochemical analyses of xenografted human lung cancer tissues and functional blood vessels

Ohno¹,

Terada²,

Bai³

et al. 2008

Cancer

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Objective: To identify the causative gene in spinocerebellar ataxia (SCA) 22, an autosomal dominant cerebellar ataxia mapped to chromosome 1p21‐q23. Methods: We previously characterized a large Chinese family with progressive ataxia designated SCA22, which overlaps with the locus of SCA19. The disease locus in a French family and an Ashkenazi Jewish American family was also mapped to this region. Members from all 3 families were enrolled. Whole exome sequencing was performed to identify candidate mutations, which were narrowed by linkage analysis and confirmed by Sanger sequencing and cosegregation analyses. Mutational analyses were also performed in 105 Chinese and 55 Japanese families with cerebellar ataxia. Mutant gene products were examined in a heterologous expression system to address the changes in protein localization and electrophysiological functions. Results: We identified heterozygous mutations in the voltage‐gated potassium channel Kv4.3‐encoding gene KCND3: an in‐frame 3‐nucleotide deletion c.679_681delTTC p.F227del in both the Chinese and French pedigrees, and a missense mutation c.1034G>T p.G345V in the Ashkenazi Jewish family. Direct sequencing of KCND3 further identified 3 mutations, c.1034G>T p.G345V, c.1013T>C p.V338E, and c.1130C>T p.T377M, in 3 Japanese kindreds. Immunofluorescence analyses revealed that the mutant p.F227del Kv4.3 subunits were retained in the cytoplasm, consistent with the lack of A‐type K+ channel conductance in whole cell patch‐clamp recordings. Interpretation: Our data identify the cause of SCA19/22 in patients of diverse ethnic origins as mutations in KCND3. These findings further emphasize the important role of ion channels as key regulators of neuronal excitability in the pathogenesis of cerebellar degeneration. ANN NEUROL 2012;72:859–869.

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“…It was shown that the energy of activation of homolysis is a good estimate of the bond dissociaton energy (BDE) for the C‐ON bond 60, 61. We determined BDE from quantum mechanical calculations and compared it with the E a values obtained by experimental study (Table 2).…”

Section: Resultsmentioning

confidence: 99%

Theoretical and experimental studies on stability of the C‐ON bond in new ketone functionalized N‐alkoxyamines

Megiel

Kaim

Cyrański

2010

J of Physical Organic Chem

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Three new ketone functionalized N-alkoxyamines derived from 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) were prepared: N-(1-phenylpropyloxy)-2,2,6,6-tetramethylpiperidin-4-one, 1-phenyl-1-(2,2,6,6-tetramethylpiperidinoxy)propanone, 1-phenyl-1-(4-oxo-2,2,6,6-tetramethylpiperidinoxy)propanone. The rate constants of C-ON bonds homolysis in the synthesized alkoxyamines were determined over a range of temperatures via nitroxide-exchange experiments using HPLC to monitor the concentration. The Arrhenius parameters of homolysis for the investigated alkoxyamines were determined (lnA, E a ). Homolytic bond dissociation energies (BDE) of the C-ON bond in the synthesized compounds were determined from quantum-mechanical calculations at the B3-LYP/6-31G(d) and BMK/ 6-311RG(3df,2p) levels. Ketone functionalization of the alkyl fragment of alkoxyamine in b position dramatically increases the rate constant of homolysis (by a factor of ca. 500 at the temperature of 363 K) suggesting that the new ketone functionalized N-alkoxyamines should be effective as C-radical precursor and unimolecular initiators in NMRP at lower temperatures than the alkoxyamines applied earlier. The analyses of natural bond, frontal orbitals and spin distribution indicated that the decrease in the strength of C-ON bonds in ketone fuctionalized alkoxyamines in the alkyl fragment predominantly originates from a substantially smaller HOMO-LUMO gap and more delocalized spin density in leaving alkyl radicals as compared with unfunctionalized alkoxyamines.

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

Cited by 15 publications

References 40 publications

Kinetic study of H‐atom transfer in imidazoline‐, imidazolidine‐, and pyrrolidine‐based alkoxyamines: Consequences for nitroxide‐mediated polymerization

Kinetic study of H‐atom transfer in imidazoline‐, imidazolidine‐, and pyrrolidine‐based alkoxyamines: Consequences for nitroxide‐mediated polymerization

Application of cryobiopsy to morphological and immunohistochemical analyses of xenografted human lung cancer tissues and functional blood vessels

Theoretical and experimental studies on stability of the C‐ON bond in new ketone functionalized N‐alkoxyamines

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