Hydrogenation dinitrobenzenes

In aq ale, or from 4-chlono-1,3-dinitrobenzene hydrogen selenide in boiling alcoholic acetic.acid (Refs 1, 2 3)... 

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... 

Nucleophilic aromatic substitutions involving loss of hydrogen are known. The reaction usually occurs with oxidation of the intermediate either intramoleculady or by an added oxidizing agent such as air or iodine. A noteworthy example is the formation of 6-methoxy-2-nitrobenzonitrile from reaction of 1,3-dinitrobenzene with a methanol solution of potassium cyanide. In this reaction it appears that the nitro compound itself functions as the oxidizing agent (10). 

The powdered dinitrobenzene, spirit and ammonia, are mixed together in a flask (i litre) and weighed. Hydrogen sulphide. 

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. 

Synthetic pyrethroids with a-cyano ester group react with sodium hydroxide to yield hydrogen cyanide, which reacts with 4-nitrobenzaldehyde and 1,2-dinitrobenzene to yield a pink-colored derivative (o-quinonoid di-anion) according to the following scheme ... 

Up to three of the hydrogens on a benzene ring can be replaced with a nitro (-NO2) group by reaction of nitric acid in sulfuric acid. When two hydrogens are replaced by nitro in this manner (dinitration), one isomer, the meta- or 1,3-, predominates. When three hydrogens are replaced (trinitration), the predominant isomer is the 1,3,5-isomer mera-dinitrobenzene is made by this method as a starting material for mera-phenylenediamine, one of the components in the manufacture of a heat-resistant nylon sold in the U.S. as Nomex by DuPont. 

Bartlett and co-workers concluded that addition to the nitro group also occurs. Price and Read found that several m-dinitrobenzene molecules were combined with the polymer for each fragment from the p-bromobenzoyl peroxide used as initiator in the retarded polymerization of styrene. They inferred that the radical corresponding to IV transfers its hydrogen atom to a molecule of styrene as follows ... 

As was the case for dinitrobenzene, the meta and para nitroaniline isomers have essentially the same gaseous enthalpy of formation. In the gaseous phase, it is surprising to find that despite the more attractive quinonoid resonance structures92 for the para isomer (58) than for the meta (59) the met a and para nitroaniline have essentially the same gas-phase enthalpy of formation. In the solid and liquid states the intermolecular stabilization lowers the enthalpy of formation of the para isomer relative to the meta. Interestingly, the gas-phase intramolecularly hydrogen-bonded ortho isomer is of comparable stability to its isomers. In contrast, it is considerably less stable than its isomers in the solid state because it can form fewer intermolecular hydrogen bonds. All isomers of nitroaniline are more stable than calculated by additivity. 

Support for this mechanism has been obtained from the study of the effect of twelve hydrogen-bond acceptors on the reactions of 1-chloro- and l-fluoro-2,4-dinitrobenzenes with morpholine in benzene162. The reaction of l-chloro-2,4-dinitrobenzene is not catalysed by either morpholine or DABCO, i.e. kA = h the first stage of the reaction is rate-determining and the various additives have no effect on the rate constant. On the other hand, Table 22 shows that the reaction of the fluoro-substrate is highly sensitive to the presence of the various additives and it is base-catalysed while for ten additives there was a linear dependence of kA on either their concentration, [P], or on the square... 

The reaction of the carbanion derived from diethyl methylphosphonate with perhalogenated aromatics may result in substitution of halide to yield perhaloaryl(hetaryl)methylphosphonates, which can be converted into tris- or bis-(perhaloaryl)methanes. Displacement of fluoride ion has been reported in the reaction of dimethoxycarbene with l-fluoro-2,4-dinitrobenzene and with hexafluorobenzene. The hydrodehalogenation of halogenated aryl ketones may be facilitated using hydrogen over a Pt/C catalyst. " ... 

The ratio of products (36) and (37) from VNS of hydrogen (Pe) and substimtion of halogen (Px), respectively (Scheme 4), will depend on the strength and concentration of base, provided that the elimination is a kinetically important step in the VNS reaction, namely Pr/Px = kikE[B]/k-ikx. The influence of base will decrease until a constant value Ph/Px = k /kx is reached as kslB] k i. This has been demonstrated for 4-chloronitrobenzene, which undergoes exclusive substimtion of chlorine unless strong base is present to favour the VNS process. The deuterium isotope effect for VNS hydroxylation by Bu OOH, determined as me ratio of H versus D substitution of l-deutero-2,4-dinitrobenzene, varied from 7.0 0.3 to 0.98 0.01 as the base in NH3 was changed from NaOH to Bu OK me former value is consistent with a rate determining E2 process. 

Hydrogen displacement from unsymmetrical substrates like 1,3-dinitrobenzene can produce a mixture of products. Reaction of 1,3-dinitrobenzene with hydroxylamine produces a mixture of 2,4-dinitroaniline and 2,6-dinitroaniline l,3-diamino-2,4-dinitrobenzene is formed if two equivalents of hydroxylamine are employed. °... 

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. 

High yields of tricyclic compounds, 4,8-dihalo- or 4,8-dinitro-substituted 1,1,3,3,5,5,7,7-octa-fluoro-5,7-dihydro-l//,3//-benzo[l,2-c 4,5-c ]difurans 13, are obtained by treatment of the dihalo- or dinitrobenzene-1,2,4,5-tetracarboxylic acids with sulfur tetrafluoride and hydrogen fluoride at elevated temperatures.132 141... 

It can be obtained by reacting sodium hydrogen ethylene glyoxide and chloro-dinitrobenzene followed by nitration, or chlorotrinitrobenzene, as reported by Faiboume and Toms [88] ... 

The synthesis of -phenylenediamine [108-45-2] is also straightforward it proceeds via the formation of / -dinitrobenzene [99-65-0] by the nitration of benzene, followed by hydrogenation to the diamine. 

Influence of the modifier structure on reaction time and chemoselectivity of the hydrogenation of l-chloro-2,4-dinitrobenzene (Raney nickel methanol 60°C 10 bar). 

Diaryl ethers, such as diphenyl ether, do not react with hydrogen iodide even at 200°.) There is no easy way to convert arenols to aryl halides, except where activation is provided by 2- or 4-nitro groups. Thus 2,4-dinitrobenzenol is converted to l-chloro-2,4-dinitrobenzene with phosphorus pentachloride ... 

The kinetics of the reactions of 1-halo-2,4-dinitrobenzenes with aliphatic amines have been used to probe solvent effects in mixtures of chloroform or dichloromethane with polar hydrogen-bond acceptors, such as DMSO. In these reactions, nucleophilic attack is rate limiting. Attempts to correlate reactivity with the empirical solvent... 

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