4,4′-Bis(dimethylamino)benzophenon (Michlers Keton) — ein universeller Indikator zur Bestimmung der Acidität, Dipolarität und Polarisierbarkeit von Reaktionsmedien
✍ Scribed by Spange, Stefan ;Keutel, Dietmar
- Publisher
- John Wiley and Sons
- Year
- 1992
- Tongue
- English
- Weight
- 652 KB
- Volume
- 1992
- Category
- Article
- ISSN
- 0947-3440
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✦ Synopsis
4,4′‐Bis(dimethylamino)benzophenone (Michler's Ketone) — a Common Indicator of the Acidity and Dipolarity/Polarizability of Reaction Media
The solvatochromisms of Michler's Ketone (1) and the iron (II) complex Fe(phen)~2~(CN)~2~ (2) has been investigated in 73 solvents of different polarity. The solvent‐induced UV/Vis‐absorption shifts of 1 and 2 are mainly attributed to both the hydrogen‐bond donor acidity and dipolarity/polarizability of the solvent as verified by a Kamlet‐Taft correlation analysis and comparison with common solvent‐polarity scales such as Reichardt's E~T~(30) values and the acceptor scale of Gutmann. Michler's Ketone exhibits the largest positive solvatochromism known so far. The specific role of phenolic solvents has been discussed with regard to a charge‐transfer complexation between the positively polarized ring of 1, caused by the hydrogen‐bond formation at the carbonyl oxygen, and the aromatic ring of the phenol.