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Papers by Birgit Weidinger

Research paper thumbnail of Cyclic Voltammetry of N,N-Dimethyl-p-Phenylenediamine and its HCl-Salt in Acetonitrile with Pyridine as Proton Acceptor

Zeitschrift für Physikalische Chemie, 2006

Summary The redox behaviour of N,N-dimethyl-p-phenylenediamine (PPD) and N,N-dimethyl-p-phenylene... more Summary The redox behaviour of N,N-dimethyl-p-phenylenediamine (PPD) and N,N-dimethyl-p-phenylenediamine · 2HCl (PPD · 2HCl) in acetonitrile was studied by means of cyclic voltammetry – both in the absence and in the presence of proton accepting pyridine. The oxidation occurs in two separate steps yielding first N,N-dimethyl-p-semiquinonediimine (SQDI+) and subsequently N,N-dimethyl-p-quinonediimine (QDI2+ or QDI+(H+)). In case of N,N-dimethyl-p-phenylenediamine the 1st oxidation step is fully reversible, while the 2nd oxidation step is slightly quasi-reversible. At 10°C the formal redox potentials of the PPD/SQDI+ and SQDI+/QDI2+ redox couples are −0.200 ± 0.005 V and 0.380 ± 0.010 V (versus Fc/Fc+), respectively. The synproportionation constant K syn = [SQDI+]2/[PPD][QDI2+] is 2.1 × 1010. Adding pyridine to the reaction mixture leads to a shift of the 2nd anodic wave to less positive potentials. This shift is primarily due to proton transfer from QDI2+ to pyridine to form QDI+, wh...

Research paper thumbnail of Cyclic Voltammetry of N,N-Dimethyl-p-Phenylenediamine and its HCl-Salt in Acetonitrile with Pyridine as Proton Acceptor

Zeitschrift für Physikalische Chemie, Apr 1, 2006

Research paper thumbnail of Cyclic Voltammetry of N,N-Dimethyl-p-Phenylenediamine and its HCl-Salt in Acetonitrile with Pyridine as Proton Acceptor

Zeitschrift für Physikalische Chemie, 2006

Summary The redox behaviour of N,N-dimethyl-p-phenylenediamine (PPD) and N,N-dimethyl-p-phenylene... more Summary The redox behaviour of N,N-dimethyl-p-phenylenediamine (PPD) and N,N-dimethyl-p-phenylenediamine · 2HCl (PPD · 2HCl) in acetonitrile was studied by means of cyclic voltammetry – both in the absence and in the presence of proton accepting pyridine. The oxidation occurs in two separate steps yielding first N,N-dimethyl-p-semiquinonediimine (SQDI+) and subsequently N,N-dimethyl-p-quinonediimine (QDI2+ or QDI+(H+)). In case of N,N-dimethyl-p-phenylenediamine the 1st oxidation step is fully reversible, while the 2nd oxidation step is slightly quasi-reversible. At 10°C the formal redox potentials of the PPD/SQDI+ and SQDI+/QDI2+ redox couples are −0.200 ± 0.005 V and 0.380 ± 0.010 V (versus Fc/Fc+), respectively. The synproportionation constant K syn = [SQDI+]2/[PPD][QDI2+] is 2.1 × 1010. Adding pyridine to the reaction mixture leads to a shift of the 2nd anodic wave to less positive potentials. This shift is primarily due to proton transfer from QDI2+ to pyridine to form QDI+, wh...

Research paper thumbnail of Cyclic Voltammetry of N,N-Dimethyl-p-Phenylenediamine and its HCl-Salt in Acetonitrile with Pyridine as Proton Acceptor

Zeitschrift für Physikalische Chemie, Apr 1, 2006

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