MEISENHEIMER ■ JANOVSKY Complexes

MEISENHEIMER-JANOVSKY Complex The adduct formed from a polynitroaromatic compound in alkaline solution with RO, HO (Meisenheimer) or with acetone (Janovsky) (see 1st edition). 

The formation of Meisenheimer s complexes o leads to interesting applications in quantitative organic analysis. Janovsky in the 1890s showed that m-dinitrobenzene... 

With an excess of the compound possessing an active methylene (Janovsky s conditions), the reaction is fast and stops at the stage-a complex. In Zimmermann s conditions, namely, with an excess of the dinitro derivative, Meisenheimer s complex is irreversibly oxidized to yield the colored anion ... 

JANOVSKY REACTION. Reaction ol aldehydes and ketones containing or-meihylcne groups with i/i-dinitrohenzcnes in the presence of a strong base, resulting in the formation of an intense purple coloration, used for the detection of carbonyl compounds. The color is due to the fnrniaiion of Meisenheimer complex. 

---