Merz, Andreas and Anikin, Sergiy and Lieser, Bernd and Heinze, Jürgen and John, Hermann (2003) 3,3 '-4,4 '-dimethoxy-2,2 '-bipyrroles: Highly electron-rich model compounds for polypyrrole formation. CHEMISTRY-A EUROPEAN JOURNAL, 9 (2). pp. 449-455. ISSN 0947-6539, 1521-3765
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3,3'-Dimethoxy-2,2'-bipyrrole (1) and 4,4'-dimethoxy-2,2'-bipyrrole (2) were obtained in short sequences and good yields from N-benzyl-3-hydroxy-pyrrole-2,4-dicarboxylic acid. The key intermediate leading to 1 is an N-benzyl-3-methoxypyrrole, which is dimerized by lithiation and oxidation with NiCl2. The formation of 2 is achieved by a classical Ullmann coupling of diethyl 1-benzyl-2-bromo-4-methoxypyrrole-3,5-dicarboxylate. The N-benzyl protection groups of 1 and 2 are cleaved under reducing conditions with sodium in liquid ammonia. Both isomeric bipyrroles are extremely sensitive toward air. Compound 1 has a very low oxidation potential of 0.09 V against AgCl but film formation hardly occurs. On the other hand, compound 2 with a potential of 0.35 V readily forms stable polypyrrole films with anodic waves at -0.51 and -0.35 V and a cathodic wave at -0.77 V the lowest potential ever observed for a p-doped polymer.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | 4,5-UNSUBSTITUTED ALKYL 3-HYDROXYPYRROLE-2-CARBOXYLATES; CONDUCTING POLYMERS; ELECTROPOLYMERIZATION; 3,4-DIALKOXYPYRROLES; OLIGOTHIOPHENES; cyclic voltammetry; oxidation; polypyrrole formation; pyrrole dimerization; reductive N-benzyl cleavage; Ullmann coupling |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 25 Aug 2021 09:51 |
| Last Modified: | 25 Aug 2021 09:51 |
| URI: | https://pred.uni-regensburg.de/id/eprint/39351 |
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