Dinitro 4,6-Dinitrobenzofuroxan

Dinitrobenzofuroxan dissolves slightly in water, giving an acid reaction, and forms a series of explosive - salts which were originally formulated as containing the anion (54). Acidification regenerates the dinitro compound. It has recently been shown that the anion is, in fact, the Meisenheimer-complex (55), on infrared, NMR, and chemical evidence, including the use of 0 and... 

Nitration at the 4-position occurs readily and further reaction gives the 4,6-dinitro derivatives. 5-Substituted analogues react similarly, 5-chlorobenzofuroxan affording the 4-nitro-5-chloro compound and subsequently 5-chloro-4,6-dinitrobenzofuroxan <84H(22)27i>. In such cases the isolated product may be the 7-substituted-4,6-dinitro compound due to rearrangement of the first-formed derivative (see Section 4.05.5.1.4). 

Azido-4,4-dmitro- 1-butyl nitrate 4,Azido-4,4-dinitro- 1-butyl acetate 7-Amino-4,6-dinitrobenzofuroxan... 

For the most reactive compounds in the series, i.e., 4,6-dinitro-benzofurazans and 4,6-dinitrobenzofuroxans, not only water222 but also methanol220 is found to be an effective neutral nucleophile in the appropriate pH range. The thermodynamic and kinetic analysis for the reactions in methanol similar to that described above for the reactions in water has been applied to the formation of 172 from 4,6-dinitro-7-methoxybenzofurazan (195) in the pH range from 2.2 to 14. The formation of 172 has been followed spectrophotometrically and found to be complete in methanol. The reaction scheme is as follows... 

Dinitrodiaethanoloxamiddinitrat 103 Dinitrodiglykol 96 dinitrodimethyloxamide 103 dinitro-dinitrosobenzene -> dinitrobenzofuroxane 101 dinitrodioxyethyloxamide dinitrate 103... 

S Ar reactions have been studied mostly with dinitro and trinitro activated benzenes. Recently, the aniline reactions with the highly activated super-electrophile, 4,6-dinitrobenzofuroxan (DNBF), have attracted considerable attention due to its ambident reactivity114. In acidic solvent, where aniline is almost completely protonated, the reaction by nitrogen attack is inhibited. However, a carbon-carbon bonded adduct is slowly formed by reaction at the 4-position of the aniline. Kinetic studies in H2O-DMSO have shown that this adduct formation involves two steps a carbon-carbon bond formation ( a), followed by elimination of a proton, Kiep (vide infra). The reactions of anilines with DNBF in DMSO have shown that the N-bonded adduct (a-N) is kinetically preferred, but the C-bonded adduct (a-C), formed in equilibrium with its deprotonated form, is the thermodynamically favored product (Scheme 14). 

This study reports on the reactions of ambident nucleophiles with electron-deficient nitroaromatic and heteroaromatic substrates anionic complex formation or nucleophilic substitution result. Ambident behavior is observed in the case of phenoxide ion (O versus C attack) and aniline (N versus C attack). O or N attack is generally kinetically preferred, but C attack gives rise to stable thermodynamic control. Normal electrophiles such as 1,3,5-trinitrobenzene or picryl chloride are contrasted with superelectrophiles such as 4,6-dinitrobenzofuroxan or 4,6-dinitro-2-(2,4,6-trinitrophenyl)benzotriazole 1-oxide (PiDNBT), which give rise to exceptionally stable a complexes. Further interesting information was derived from the presence in PiDNBT of two electrophilic centers (C-7 and C-l ) susceptible to attack by the ambident nucleophilic reagent. The superelectrophiles are found to exhibit lesser selectivity toward different nucleophilic centers of ambident nucleophiles compared with normal electrophiles. 

The first salts of 4,6-dinitrobenzofuroxan (potassium, sodium, ammonium, and silver) were prepared by Drost in 1899. The product of precipitation of 4,6-DNBF by potassium bicarbonate was however misidentified as the potassium salt of m-dinitro-o-dinitrosobenzene. The other salts were also thought to be salts of the... 

Potassium salt of 7-hydroxylamino-4,6-dinitro-4,7-dihydrobenzofuroxan can be prepared in the same way as KDNBF. It is formed by the reaction of 4,6-dinitrobenzofuroxan with hydroxylamine in presence of a methanolic solution of potassium bicarbonate. The yield is nearly quantitative [48]. 

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