Janovsky adducts

An apparently similar reaction has been described by Zimmerman (1935, 1936). However, here the dinitrobenzene is used in excess and the solvent is ethanol. It has been shown that the colour in these solutions results from anions such as 43 (Neunhoeffer et al., 1961 King and Newall, 1962) which are derived from the initially formed Janovsky adduct by oxidation with the excess nitro-compound. 

MEISENHEIMER JANOVSKY Corryilexes The adduct formed from a polynAroaromaiic compourxf in alkaline solution with RO, HO (Melsenheimer) or with acetone (Janovsky)... 

The first observations in this area were made 100 years ago, when in 1886 Janovsky and Erb (16) reported the formation of an intensely colored purple substance in the reaction of acetone with 1,3-dinitrobenzene (DNB) in alkaline solution. After a period of controversy as to whether the structure of the species formed was 1 or 2 (17-19), the 2 was unambiguously proven by -NMR spectroscopy (20). The corresponding adduct of 1,3,5-trinitrobenzene (TNB), which is also obtained readily on solvolysis of the TNB CH30 complex in acetone, was similarly shown by -NMR spectroscopy to have the structure 3 (21). More recent 13C and 15N-NMR spectroscopic studies confirmed these formulations (22). The structures of a complexes such as 3 are now more correctly depicted as the delocalized species, in accord with experimental results (e.g., X-ray crystal structure) and theoretical considerations (23)... 

Unequivocal evidence for the formation of o -adducts has been obtained by X-ray diffraction analysis of those adducts which are stable enough to obtain their single crystals [11]. Indeed, the X-ray crystallography data are available for the anionic trinitrobenzene-methoxide and the Janovsky trinitrobenzene-acetone complexes [11, 201, 202] and for the o -adducts of isoquinoline [203], phthalazine [160], and 4,7-phenanthroline [161, 162] with dialkyl phosphonates. Also the X-ray data have been obtained for the neutral o -adducts resulting from the reactions of iV-methylacridinium ion with N-nucleophiles [204, 205] and for the o -adducts of iV-alkyl-substituted 2,3-dicyanopyrazinium and quinoxalinium salts with 0-, C-and P-nucleophiles [163, 194]. 

---