Preparation of Some Homologous TEMPO Nitroxides and Oxoammonium Salts; Notes on the NMR Spectroscopy of Nitroxide Free Radicals; Observed Radical Nature of Oxoammonium Salt Solutions Containing Trace Amounts of Corresponding Nitroxides in an Equilibrium Relationship

James M. Bobbitt, Nicholas A. Eddy, Clyde X. Cady, Jing Jin, Jose A. Gascon, Svetlana Gelpí-Dominguez, Jerzy Zakrzewski, Martha D Morton

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Three new homologous TEMPO oxoammonium salts and three homologous nitroxide radicals have been prepared and characterized. The oxidation properties of the salts have been explored. The direct 13C NMR and EPR spectra of the nitroxide free radicals and the oxoammonium salts, along with TEMPO and its oxoammonium salt, have been successfully measured with little peak broadening of the NMR signals. In the spectra of all ten compounds (nitroxides and corresponding oxoammonium salts), the carbons in the 2,2,6,6-tetramethylpiperidine core do not appear, implying paramagnetic properties. This unpredicted overall paramagnetism in the oxoammonium salt solutions is explained by a redox equilibrium as shown between oxoammonium salts and trace amounts of corresponding nitroxide. This equilibrium is confirmed by electron interchange reactions between nitroxides with an N-acetyl substituent and oxoammonium salts with longer acyl side chains.

Original languageEnglish (US)
Pages (from-to)9279-9290
Number of pages12
JournalJournal of Organic Chemistry
Volume82
Issue number18
DOIs
StatePublished - Sep 15 2017

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Nuclear magnetic resonance spectroscopy
Free Radicals
Salts
Nuclear magnetic resonance
Paramagnetism
TEMPO
Interchanges
Paramagnetic resonance
Carbon
Oxidation
Electrons

ASJC Scopus subject areas

  • Organic Chemistry

Cite this

Preparation of Some Homologous TEMPO Nitroxides and Oxoammonium Salts; Notes on the NMR Spectroscopy of Nitroxide Free Radicals; Observed Radical Nature of Oxoammonium Salt Solutions Containing Trace Amounts of Corresponding Nitroxides in an Equilibrium Relationship. / Bobbitt, James M.; Eddy, Nicholas A.; Cady, Clyde X.; Jin, Jing; Gascon, Jose A.; Gelpí-Dominguez, Svetlana; Zakrzewski, Jerzy; Morton, Martha D.

In: Journal of Organic Chemistry, Vol. 82, No. 18, 15.09.2017, p. 9279-9290.

Research output: Contribution to journalArticle

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abstract = "Three new homologous TEMPO oxoammonium salts and three homologous nitroxide radicals have been prepared and characterized. The oxidation properties of the salts have been explored. The direct 13C NMR and EPR spectra of the nitroxide free radicals and the oxoammonium salts, along with TEMPO and its oxoammonium salt, have been successfully measured with little peak broadening of the NMR signals. In the spectra of all ten compounds (nitroxides and corresponding oxoammonium salts), the carbons in the 2,2,6,6-tetramethylpiperidine core do not appear, implying paramagnetic properties. This unpredicted overall paramagnetism in the oxoammonium salt solutions is explained by a redox equilibrium as shown between oxoammonium salts and trace amounts of corresponding nitroxide. This equilibrium is confirmed by electron interchange reactions between nitroxides with an N-acetyl substituent and oxoammonium salts with longer acyl side chains.",
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