1.3.5- trinitrobenzene reactivity

Grisham, M.B., Volkemer, C., Tso, P. and Yamada, T. (1991). Metabolism of trinitrobenzene sulfonic acid by the rat colon produces reactive oxygen species. Gastroenterology 101, 540-547. 

These treatments have been also applied to S/yAr. For example, for a neutral nucleophile, all the classical pathways identified at present are represented by the general reaction mechanism shown by Scheme 2. A concerted mechanism, indicated by the diagonal path in Scheme 2, had not been discussed until lately, but was observed, among other systems, in the hydrolysis of l-chloro-2,4,6-trinitrobenzene and 1-picrylimidazole. The study was then extended to other related substrates and structure-reactivity relationships could be obtained78. 

Nitronium salts in sulfuric, triflic or fluorosulfuric acids are extremely reactive and well suited for the polynitration of deactivated substrates. Olah and Lin" studied the nitration of m-dinitrobenzene to 1,3,5-trinitrobenzene with a solution of nitronium tetrafluoroborate in fluorosulfuric acid at 150 °C. An optimum yield of 66 % was obtained after a reaction time of 3 hours. However, the crude reaction mixture was found to contain 17 % unreacted m-dinitrobenzene. After a reaction time of 3.8 hours the yield of 1,3,5-trinitrobenzene dropped to 50 % but the product was free from m-dinitrobenzene and was essentially pure. 

In a similar manner, of the isomeric trinitrobenzenes, only the symmetrical 1,3,5-isomer shows sufficient chemical stability for use as an explosive. Even so, the aromatic ring of 1,3,5-trinitrobenzene is highly electron deficient and reaction with alkali metal carbonates or bicarbonates in aqueous boiling methanol yields 3,5-dinitroanisole. Unsymmetrical isomers of trinitrobenzene are much more reactive than the 1,3,5-isomer, with only relatively mild conditions needed to effect the displacement of their nitro groups. ... 

Highly-colored Jackson-Meisenheimer,or a, complexes of structure II or III are formed by addition to the ring system. The controversial history of the study of these compds has been well reviewed (Refs 44,46,51,70 82). They are formed in aq and anhydrous medium, and with a variety of organic and inorganic nucleophiles. Most of these studies have been made with 1,3,5 -trinitrobenzene rather than TNT, since the absence of a reactive methyl group in the former simplifies product isolation and identification. 

The source of cyanide ions is the Meisenheimer adduct formation between trinitrobenzene and cyanide ions in equilibrium 25. The constant of this equilibrium 25 is well known if the equilibrium concentration of free cyanide ions is negligible, the concentration of the strong red 137 provides a proof of equilibrium 24. Also, in the case of equilibrium 24, DMSO enhances the reactivity of the anionic nucleophile compared with protic solvents. 

Other 7r-complexing reagents are 1,3,5-trinitrobenzene and 2,4,7-trinitro-9-fluorenone (1). The crystalline adducts are usually formed in ethanol, glacial acetic add, or toluene solution and recrystallised from similar solvents. They are useful both for the characterisation and also for the isolation of appropriately reactive aromatic hydrocarbons. 

There is current interest in the quantitative comparison of electrophilicities and nucleophilicities, particularly in carbon-carbon bond-forming reactions. The rates of a-adduct formation in acetonitrile of 10 electron-deficient aromatics and heteroaromatics with a series of reference carbon nucleophiles have been used to compare their electrophilicities, E. Values of E ranging from —13.2 for 1,3,5-trinitrobenzene, the least reactive studied, to -4.7 for 4,6-dinitrotetrazolo 1,5-a Ipyridinc, the most reactive, were determined.52 A reasonable correlation was found between electrophilicities and pA a values for water addition (eq. 1). These pA a values have also been found to... 

Addition of methoxide ion in methanol For reactive substrates, such as 1,3,5-trinitrobenzene, which are converted into complex in dilute solutions of sodium methoxide, the equilibrium constant, Kx, is adequately expressed in terms of concentrations as [A]/[P][OMe-]. However, for less reactive substrates, such as dinitrobenzenes, significant conversion to complex only occurs at fairly high concentrations of sodium methoxide similarly for the higher equilibria of trinitro-substituted benzenes. In these solutions the basicity of the medium cannot be adequately described by the con-... 

The greater stability of the 1 1 adducts in aprotic solvents is, then, attributed mainly to the enhanced reactivity of the attacking nucleophiles in these solvents. This factor should also favour the production of di-adducts in aprotic solvents and NMR measurements do indicate that these are formed from trinitro-substituted compounds and methoxide ions in media rich in dimethyl sulphoxide. However, there is some evidence that the di-adducts are not particularly well solvated by dimethyl sulphoxide and are in fact better solvated by water. Thus it has been found that 1 2 adducts are very readily formed in water. For example 1,3,5-trinitrobenzene gives both 1 1 and 1 2 adducts in fairly dilute solutions of hydroxide ions in water, while dimethyl-picramide and the picrate ion give evidence only for the production of 1 2 adducts. Similarly a variety of trinitro-compounds are readily converted into di-adducts in aqueous sodium sulphite solution, although... 

The chlorine atom in 1-chloro-2,4,5-trinitrobenzene becomes reactive only at higher temperatures. 

Not surprisingly, three nitro groups have an even greater influence on the reactivity of the halogen and 1-chloro-2,4,6-trinitrobenzene (picryl chloride) is hydrolysed to 2,4,6-trinitrophenol (picric acid) in boiling water. The trivial names tell us that this aryl halide behaves as an acyl halide and the phenol as an acid. 

Several enzyme-linked immunosorbent assays (ELISAS) have been developed for trinitrotoluene, trinitrobenzene, 2,4-dinitrotoluene, and 2,6-dinitrotoluene using polyclonal antibodies raised in New Zealand white rabbits. Nitro substituted benzoic and phenyl acetic acids were used as haptens by conversion to the correspond NHS esters followed by coupling to protein carriers.The antibodies which were developed to 1,3-dinitroaromatic haptens had the greatest specificity and sensitivity when the nitroaromatic analytes contained a 1,3-dinitro functionality. In one ELISA system a lower detection limit for various 1,3-dinitroaromatics analytes of 1 ng/mL with an I50 of 5 ng/mL was observed. No cross reactivity with mononitroaromatic compounds was observed. Antibodies developed to mononitroaromatic haptens showed high affinity for a variety of coating antigens but would not compete with nitroaromatic analytes in a normal ELISA. 

Addition of methoxide ion in methanol For reactive substrates, such as 1,3,5-trinitrobenzene, which are con-... 

The second variable is the nature of the attacking nucleophile and we shall consider first the reactivities of a series of nucleophiles towards a single substrate. Perhaps the most studied compound is 1,3,5-trinitrobenzene and the equilibrium constants for formation of 1 1 adducts with a variety of nucleophiles are given in Table 7. However the stability of a given adduct will vary considerably with change of solvent so that values obtained in different solvents are not comparable. 

Common ion rate depression for solvolysis of RX with the same R but with different leaving groups X was followed only for a single system. From the a values obtained in the solvolysis of ( )- and (Z)-l,2-dianisyl-2-phen-ylvinyl-X, 16, in AcOH-AcO- (equation 9), relative reactivities toward the derived ion 17 were measured (74) (nucleophile, relative reactivity) OMs-, 0.16 OAc, 1.0 Cl , 15.2 Br 45.5 and AcOH, 0.0024. From other data, I will probably be at the top of a similar order (75) and 2,4,6-trinitrobenzene-sulfonate at the bottom (76). 

It is impossible to introduce more than three nitro groups into one benzene ring the products would contain at least two nitro groups in the ortho-position to one another, and such compounds are very reactive. The two isomeric tetranitrobenzenes should be preparable by oxidation of other nitrogenous groups present in trinitrobenzene derivatives.169 In di- and tri-nitrations the nitro groups normally enter positions meta to one another, in accord with the well-known rules of substitution. However, occasionally, when these rules are overcome by some specific activation by other substituents, 0-dinitro compounds will result for instance, about 4% of m-nitrotoluene is formed on mononitration of toluene and on further nitration this leads to a mixture of 2,3-, 3,4-, and 3,6-dinitrotoluenes. 

Finally, reactivity degree four (4) chemicals, the most dangerous group, are materials which are easily capable of detonation at normal temperatures, or may undergo explosive decomposition or reaction under normal conditions. Dibenzoyl peroxide, picric acid, tertiary butyl hydroperoxide, ethyl nitrite, and trinitrobenzene are representative of degree four (4) chemicals. 

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