Dinitrobenzene, amination

Only the mono-amines are described here. The diamines are more frequently encountered as reduction products of dinitrobenzenes and nitro-anilines, and the chief reactions of the phenylenediamines are therefore given in Section 23, pp. 384-388. 

It is convenient to include under Aromatic Amines the preparation of m-nitroaniline as an example of the selective reduction of one group in a polynitro compound. When wt-dinitrobenzene is allowed to react with sodium polysulphide (or ammonium sulphide) solution, only one of the nitro groups is reduced and m-nitroanUine results. Some sulphur separates, but the main reaction is represented by ... 

Catalytic hydtogenation is the most efficient method for the large scale manufacture of many aromatic and ahphatic amines. Some of the commercially important amines produced by catalytic hydrogenation include aniline (from nitrobenzene), 1,6-hexanediamine (from adiponitrile), isophoronediamine (from 3-nitro-l,5,5-trimethylcyclohexanecarbonitrile), phenylenediamine (from dinitrobenzene), toluenediamine (from dinitrotoluene), toluidine (from nitrotoluene), and xyhdine (from nitroxylene). As these examples suggest, aromatic amines ate usually made by hydrogenating the... 

Another example of the analogy between pyrazole and chlorine is provided by the alkaline cleavage of l-(2,4-dinitrophenyl)pyrazoles. As occurs with l-chloro-2,4-dinitrobenzene, the phenyl substituent bond is broken with concomitant formation of 2,4-dinitrophenol and chlorine or pyrazole anions, respectively (66AHC(6)347). Heterocyclization of iV-arylpyrazoles involving a nitrene has already been discussed (Section 4.04.2.1.8(i)). Another example, related to the Pschorr reaction, is the photochemical cyclization of (515) to (516) (80CJC1880). An unusual transfer of chlorine to the side-chain of a pyrazole derivative was observed when the amine (517 X = H, Y = NH2) was diazotized in hydrochloric acid and subsequently treated with copper powder (72TL3637). The product (517 X = Cl, Y = H) was isolated. 

Later in the 20th century, Vompe and Stepanov delineated efficient procedures for the preparation of the so-called Zincke salts (e.g., 1) from pyridines and 2,4-dinitrochlorobenzene, involving, for example, reflux in acetone. Vompe and Lukes also noted that electron-donating substituents on the pyridinium ring of the Zincke salt retarded reaction with amines at the 2-position of the pyridinium ring, sometimes leading instead to attack at the C-1 position of the 2,4-dinitrobenzene ring, with displacement of the pyridine. 

The catalytic effect of aromatic nitro groups in the substrate and product or in an added inert nitro compoimd (e.g., w-dinitrobenzene in 18) has been observed in the reaction of 2,4-dinitrochlorobenzene with an amine in chloroform. Hydrogen bonding to benzil or to dimethyl sulfone and sulfoxide also provided catalysis. It is clear that the type of catalysis of proton transfer shown in structure 18 will be more effective when hydrogen bonding is to an azine-nitrogen. 

Aromatic amines and phenols [1-4] e.g. resorcinol, catechol, aminonaphthols Indol m-dinitrobenzene Ruene [2] Sulfapyridine [2, 3] ... 

SNAr substitutions of activated aromatic halides, especially aromatic fluorides, provide useful means for the construction of aromatic diethers or amines. Primary and secondary amines react with l, 2-dihalo-4,5-dinitrobenzene to give nitro group substitution at room temperature. The halogen substituents on the ring remain unsubstituted and can be used in further transformation (Eq. 9.5).8... 

Interesting direct animation of nitroarenes has been reported aromatic photo substitution of m-dinitrobenzene with primary amines is promoted by the presence of fluoride ion to give useful yields of the product (Eq. 9.46).78... 

TABLE 1. Apparent stability constant (Kc) of complexes between aromatic amines and l-fluoro-2,4-dinitrobenzene (unless otherwise indicated) at 40 °C... 

Furthermore, in many cases, changes in the mechanism have also been observed and they will be discussed in a later section. Nevertheless, by selecting a system that exhibited the same rate-determining step in a variety of solvents it would be possible to assess how the rate of a given process may be affected by a solvent transfer. Such is the case of the reaction of l-chloro-2,4-dinitrobenzene with piperidine, where the rate dependence with amine concentration has been studied in 12 aprotic solvents483 as well as in 10 protic solvents4815. It was found that the reaction does not exhibit base catalysis in any of the solvents studied that is, addition of piperidine is rate-limiting in all the... 

When the decomposition of the zwitterionic intermediate is rate-determining, the effect of the solvent is crucial since it may produce changes in the mechanisms and in the rate-determining step. A recent study of the kinetics of the reactions of 1-chloro-, 1-fluoro- and l-phenoxy-2,4-dinitrobenzene with piperidine, n-butylamine and benzylamine in ethyl acetate and THF indicated that these reactions resemble those in dipolar aprotic solvents when primary amines are the nucleophiles (i.e. that shown in equation 1, with... 

SjvAr reactions of nitroaromatics such as l-chloro-2,4-dinitrobenzene and 2,4,6-trinitroanisole with amines are accelerated in micelles or microemulsions49. As with anionic nucleophiles, the rate enhancement is mainly the effect of a high local concentration of both reactants18,31. 

Recently, the same group79 have reported the kinetic study of the reaction of l-pyrrolidino-2,4-dinitrobenzene, l-piperidino-2,4-dinitrobenzene and 1-morpholino-2,4-dinitrobenzene with NaOH in the presence of the amine leaving group and proposed the formation of cr-complexes, which were found to react faster than the original substrates. 

Recently, Forlani129 studied the reactions of fluoro dinitrobenzene (FDNB) with several amines in the presence of some compounds that have been found to catalyse the reaction. The plots of k0bs vs [catalyst] show a linear dependence at low catalyst concentration and then a downward curvature. This behaviour has been previously observed in several related cases the usual interpretation is that the k0bs increases on increasing the [catalyst] value until it reaches a maximum when k- = k + k2 [catalyst]. 

A new assumption to be discussed in this section is that the fourth-order kinetics in SatAr by amines in aprotic solvents is due to the formation of the substrate-catalyst molecular complex. Since 1982, Forlani and coworkers149 have advocated a model in which the third order in amine is an effect of the substrate-nucleophile interaction on a rapidly established equilibrium preceding the substitution process, as is shown in Scheme 15 for the reaction of 4-fluoro-2,4-dinitrobenzene (FDNB) with aniline (An), where K measures the equilibrium constant for ... 

Aliquat (0.2 g, 0.5 mmol) is added to the amine (l 4.5 mmol) in H20 (25 ml) and 1,2,3,4-tetrachloro-5,6-dinitrobenzene (2.0 g, 6.5 mmol) in PhMe (25 ml). The two-phase system is stirred under reflux for ca. 1 h and then cooled. The organic phase is separated, dried (MgS04), and evaporated. Chromatography of the residue from silica gives the aniline. 

Selected examples of the reaction of 1,2,3,4-tetrachIoro-5,6-dinitrobenzene with amines... 

The effect which amino functionality has on the thermal and impact sensitivity of polyni-troarylenes (Section 4.8.1.4) makes amination by VNS a method with much future potential for energetic materials synthesis. Other carbon, nitrogen, oxygen and sulfur nucleophiles can displace aromatic hydrogen examples with 1,3-dinitrobenzene and 1,3,5-trinitrobenzene are extensive. 

Lysine is an essential amino acid with an e-amino group on the side chain that can react with various food components. As known, reaction of the e-amine can render lysine nutritionally unavailable reducing the nutritional value of food. While the determination of total lysine is straightforward (it is stable to acid hydrolysis), the determination of available lysine is difficult as lysine adducts are labile to the standard acid hydrolysis. A solution to this problem consists of derivatizing the e-amino group with a chromophore such as l-fluoro-2,4-dinitrobenzene (FDNB) to form a derivate which is stable to optimized hydrolysis conditions [222]. 

Tr in itro-4-ami no diphenyl amine, HaN -C,Hs(NOa )-NH-C6Hs(NOa)a. Red-brn ndls (from AcOH), mp 226°. Can be prepd from 2-nitro-l,4-phenylenediamine and 4-chloro-1,3" dinitrobenzene. Its expl props were not in-ve sti gated... 

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