Electrochemical Oxidation of Aromatic Nitrogen Compounds

Aromatic nitrogen compounds such as anilines and triazenes react in oxidations both in nature and in chemical synthesis. The oxidative intermediates are often very reactive and responsible for e.g. the carcinogenic as well as therapeutic action of triazenes. We investigate the mechanisms and kinetics of the aniline and triazene oxidation by electrochemical and spectroscopic techniques. Intermediates (e.g. radical cations) are isolated and/or characterized. The reactions of diazonium ions, generated by electrochemical oxidation from triazenes are used to prepare heterocyclic systems (triazoles, pyrazoles). The electrochemical formation of chinol ethers from anilines is performed in a combinatorial way.

Coworkers in this project:

Bernhard Gollas, Peter Hertl, Hartmut Stahl, Matthias Vollmer and Xudong Wei

We acknowledge funding of this project by the Deutsche Forschungsgemeinschaft, Bonn - Bad Godesberg and the land Baden-Württemberg within a Landesforschungsschwerpunkt.

Publications from this project:

W. Märkle, B. Speiser und M. Vollmer, Electrochim. Acta, 50, 2753 - 2762 (2005); Combinatorial Micro Electrochemistry. Part 1. Automated Micro Electrosynthesis of Iminoquinol Ether and [1,2,4]Triazolo[4,3-a]pyridinium Perchlorate Collections in the Wells of Microtiter Plates.

X. Wei und B. Speiser, Electrochim. Acta, 42, 73 - 79 (1996); Ring Formation from 2-Arylazo-3-aminocrotononitriles to 1,2,3[2H]-triazole-4-carbonitriles and Pyrazoles by Anodic Oxidation.

X. Wei und B. Speiser, Electrochim. Acta, 40, 2477 - 2482 (1995); Electrochemistry of Triazenes. Part 4. Reaction of Diazonium Ions Generated Electrochemically from 1-Aryl-3,3-dimethyltriazenes in Acetonitrile.

L. Dunsch, B. Gollas, A. Neudeck, A. Petr, B. Speiser und H. Stahl, Chem. Ber., 127, 2423 - 2429 (1994); Electrochemistry of Triazenes. Part 3. One-Electron Oxidation of Aryltriazenes to Radical Cations.

B. Speiser und H. Stahl, Tetrahedron Lett. 33, 4429 - 4432 (1992); Electrochemistry of Triazenes. Part 2. Formation of the 2,7-Dimethoxy-5,10-dimethyl-5,10-dihydrophenazine Radical Cation during Oxidation of 1,3-Diaryl-3-methyltriazenes.

A. Rieker, P. Hertl und B. Speiser, in R. Louw und P. Mulder (Hrsg.), Proc. Sixth Int. Symp. Org. Free Rad., Noordwijkerhout, Niederlande, 1992, S. 256 - 259 (ISBN: 90-9004445-0); Persistent Radicals Derived from Primary Anilines.

B. Gollas und B. Speiser, Angew. Chem., 104, 336 - 338 (1992); Angew. Chem. Int. Ed. Engl., 31, 332 - 334 (1992); Elektrochemie von Triazenen. Teil 1. Elektrochemische Oxidation von 1-p-Dimethylaminophenyl-3,3-dimethyltriazen -- Cyclovoltammetrischer Nachweis eines Triazen-Radikalkations und -Dikations.

B. Speiser and A. Rieker, J. Org. Chem., 56, 4664 - 4671 (1991); Electrochemistry of Anilines. Part 6. Reactions of Electrogenerated Biphenylyl Nitrenium Ions.

P. Hertl, A. Rieker und B. Speiser, J. Electroanal. Chem., 301, 37 - 52 (1991); Electrochemistry of Anilines. Part 4. Determination of Rate and Equilibrium Constants for the Protonation of 2,6-Di-tert-butyl-4-(4^′-R-phenyl)-anilines in Acetonitrile from Cyclic Voltammetric Data. Erratum: J. Electroanal. Chem. 306, 313 (1991).

A. Rieker und B. Speiser, Tetrahedron Lett. 31, 5013 - 5014 (1990); Electrochemistry of Anilines. Part 5. Spectroscopic and Electrochemical Characterization of a Persistent Biphenylyl Nitrenium Ion.

P. Hertl, A. Rieker und B. Speiser, J. Electroanal. Chem. 200, 147 - 158 (1986); Electrochemistry of Anilines. Part III. Electrochemical Oxidation of Sterically Hindered 4-Aminobiphenyls and Correlation of Formal Potentials with Hammett σ Values.

B. Speiser, A. Rieker und S. Pons, J. Electroanal. Chem. 159, 63 - 88 (1983); Electrochemistry of Anilines. Part II. Oxidation to Dications, Electrochemical and UV/VIS Spectroelectrochemical Investigation.

B. Speiser, A. Rieker und S. Pons, J. Electroanal. Chem. 147, 205 - 222 (1983); Electrochemistry of Anilines. Part I. Oxidation of 2,6-Di-tert-butyl-anilines to Radical Cations: General Considerations, Electroanalytical Experiments and Spectroscopy.