Janovsky reaction

St CA 71, 9479(1969) (Colorimetry of alkylamines, guanidines, and quaternary ammonium salts by the Janovsky Reaction) (Free Gu from its salt with AgO in the presence of nitromethane and TNB colori-metrically measure the red compd formed)... 

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. 

The reaction of 1,3-dinitrobenzene with alkaline acetone to give a purple-coloured solution was noted as early as 1886 by Janovsky and Erb and is now known as the Janovsky reaction . Since then strong colours have been observed from a variety of active methylene compounds and the reaction is used as a test for them. Much of the literature has been summarized by Canback (1949a, 1949b), who suggested the structure 42, and more recently by Pollitt and Saunders (1965). Chemical and spectroscopic evidence is in support of formula 42 and dark purple crystals have been prepared (Gitis and Kaminskii, 1963, 1964 Kimura et al., 1965). Oxidation with hydrogen peroxide in acidic... 

The so-called Janovsky reaction [53] is a very characteristic one for many higher nitrated benzene derivatives. It is probably also of nucleophilic character. It consists in treating a diluted di- or tri-nitro compound solution in acetone with a concentrated solution of potassium or sodium hydroxide (generally of 30% concentration). The acetone solution turns bright coloured. Red to violet colours may appear according to the nitro compound present. 

The Janovsky reaction and its Bitto modification were investigated by Rei-tzenstein and Stamm [55], Both these as well as other authors (Bost and Nicholson [56], Nisida [57], Canack [58]) stated a number of irregularities. 

Absorption spectra of coloured compounds produced by the Janovsky reaction... 

Gitis believes that compounds of the V type are the main products of the Janovsky reaction. 

An acetone solution of 2,4-dinitrotoluene treated with a 10 per cent solution of KOH gives a blue colour (the Janovsky reaction), unlike the 2,6-isomer, which gives no colour at all. 

One of the characteristic features of aromatic nitro compounds, particularly those with two or more nitro groups is their ability to react with bases and in many instances the reaction is accompanied by an intense colour. The colour had caught the attention of chemists by the late nineteenth century and initiated a considerable amount of research on the nature of the formed substances. Thus considerable literature appeared on reactions known as Janovsky or Jackson-Meisenheimer or Meisenheimer reactions which are discussed later. They are nucleophilic reactions and are not only of theoretical but also of practical importance. Thus the Janovsky reaction became an important analytical method, and reactions of di- and trinitrobenzene and their homologues with bases, are of great importance in the problem of the safety of manufacture and of the stability of these nitro compounds. 

The Janovsky reaction became an important analytical test which could be used to detect both reagents di- or trinitro rompounds or ketones and aldehydes. The modification of the reaction consisting in the use of m-dinitrobenz-ene as a test for 17-ketosteroids is sometimes called the Zimmerman reaction [15,56). 

The Janovsky reaction was reviewed by Hail and Poranski (10), Buck [15], Strauss [17] and more recently by Gitis and Kaminskii [57]. The structure given in Vol. 1, p. 209 is now regarded as incorrect. Instead formulae Vila, VIlb and for 1,3,5-trinitrobenzene VIII (see also Vol. I, pp. 210-211) are now accepted. They were suggested by Hantzsch and Picton [58] as early as 1909 and more proof was given in their favour by Gitis and Kaminskii [59], Foster and Fyfe [60], Severin and Schmitz [61 ] and Kimura [62]. 

These compounds however form the first step of the Janovsky reaction. They can further react to yield bicyclic products (IX) according to Strauss and Schran [17,63], Kohashi, Ohkura and Momosa [64] (7)... 

Jackson-Meisenheimcr reaction and nucleophilic reactions 102 nucleophilic addition and substitution 97-98(1/197)... 

The pharmacopoeia test is quite unique in that a content of nitrate under the conditions given will react with nitrobenzene to give m-dinitrobenzene, which then will react with acetone to form a colored product indication a positive reaction. The methodology of this second reaction was first described in literature in 1939 by Pesez and is based on the Janovsky reaction that for many years was widely used for the colorimetric/photometric determination of substances sometimes referred to as methyl ketones. ... 

Other references related to the Janovsky reaction are cited in the literature. 

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