L-Chloro-2,4,-dinitrobenzene

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. 

Heterocyclic bases which readily form quaternary salts with the more usual reagents will also react with suitably activated aryl and heterocyclyl halogen compounds, the classic case being the salt formed from pyridine and l-chloro-2,4-dinitrobenzene. Reactions of this type have been studied by Chapman et Salt formation between... 

Beagent 1 Spray solution 1 Dissolve 2 g l-chloro-2,4-dinitrobenzene in 100 ml ethanol. 

Nicotinic acid and related compounds react with l-chloro-2,4-dinitrobenzene in the manner of the cyanogen bromide reaction to yield derivative I, which possibly also decarboxylates at elevated temperature. In alkaline medium this derivative first adds an hydroxyl ion and then undergoes ring opening to yield the colored derivative II. 

Reaction between glutathione and reactive chloro compounds such as l-chloro-2,4-dinitrobenzene (Niimi et al. 1989), or the chloroacetamide group in demethylated metolachlor (Cruz et al. 1993). 

See l-Chloro-2,4-dinitrobenzene Ammonia See entry high rate decomposition... 

The hydroxy-nitro dye Naphthol Yellow S (6.233 Cl Acid Yellow 1) was discovered in 1879 by Caro and is still manufactured. It is produced by sulphonation of 1-naphthol to give l-naphthol-2,4,7-trisulphonic acid, followed by replacement of the 2- and 4-sulpho groups in nitric acid medium. Nucleophilic substitution of l-chloro-2,4-dinitrobenzene with 4-aminodiphenylamine-2-sulphonic acid gives Cl Acid Orange 3 (6.234). 

The chemical reactivity of crown-ether complexes with neutral molecules has received little attention. Nakabayashi et al. (1976) have reported crown-ether catalysis in the reaction of thiols with l-chloro-2,4-dinitrobenzene. The catalytic activity was attributed to deprotonation of thiols by dicyclohexyl-18-crown-6 in acetonitrile solution. Blackmer et al. (1978) found that the rate of aquation of the cobalt(III) complex [333] increases on addition of... 

Apparent stability constants for interactions between l-chloro-2,4-dinitrobenzene and benzene or mesitylene were found to be 0.76 and 0.96 (moD1 dm3) respectively, and between 4-chloro-3-nitrotrifluoromethylbenzene and benzene or mesitylene the values were 0.96... 

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... 

TABLE 2. Second-order reaction rate coefficients, a> at 15, 25 and 40 °C, and activation parameters for the reactions 10-4 M of l-chloro-2,4-dinitrobenzene with piperidine in hydroxylic solvents4813... 

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. 

These studies have been recently extended to the reaction of n-butylamine (di-BA) and piperidine (PIP) with other aromatic substrates, such as l-chloro-2,4-dinitrobenzene (CDNB) and 4-chloro-3-nitrotrifluoromethylbenzene (CNTFB) in hexane, benzene, mesitylene and binary mixtures of hexane with the aromatic solvents, and the results are consistent with Scheme 4 which includes the proposal of a preferential solvation with the donor solvent, D115. As expected, a decrease in rate was observed in the reactions with butylamine with increasing amounts of the donor solvent, which was attributed to the formation of the EDA complex with the solvent. The result is expressed by equation 18 which, in the limiting case where Ks [Pg.1247]

Dinitrobenzene. e 1 -Chloro-4-nitro-benzene. f l-Chloro-2,4-dinitrobenzene. 

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... 

There has been a useful review of phase-transfer catalysis in nucleophilic aromatic substimtion. A comparison has been reported of the reactions with nucleophiles of l-chloro-2,4-dinitrobenzene (substimtion) and 4-nitrophenyl diphenyl phosphate (dephosphorylation) in neutral micelles of dodecyl (10) and (23) polyoxyethylene glycol. In the substimtion reaction considerable amounts of ether may be formed by reaction with alkoxide ions at the micellar surface. Differences in reactivity of the two substrates are probably due to differences in their location in the micellar structures. ... 

The electrochemical behavior of l-fluoro-2,4-dinitrobenzene, l-chloro-2,4-dinitrobenzene, and l-bromo-2,4-dinitrobenzene in DMF was described (Gallardo et al. 2000) as follows. The 1-fluoro-2,4-dinitrobenzene anion-radical dimerizes before cleavage, whereas l-chloro-2,4-dinitrobenzene... 

The chlorine —fluorine exchange in l-chloro-2,4-dinitrobenzene has been systematically investigated using potassium fluoride among other reagents in the presence of several crown ethers.93... 

Rubidium fluoride is a fairly expensive reagent and has been used rarely in replacing halogens and sulfonates with fluorine. l-Chloro-2,4-dinitrobenzene (19) has been reacted with rubidium chloride to give l-fluoro-2,4-dinitrobenzene (20).185... 

Dynamic Docking Study of the Binding of l-Chloro-2,4-Dinitrobenzene in the Putative Electrophile Binding Site of Naturally Occurring Human Glutathione S-Transferase pi Allelo-Polymorphic Proteins... 

Abbreviations CDNB, l-chloro-2,4-dinitrobenzene GSH, glutathione GS-DNB, l-(S-glutathionyl)-2,4-dinitrobenzene GST, glutathione-S-transferase NBD-C1, 7-chloro-4-nitrobenzo-2-oxa-l,3-diazole EA, ethacrynic acid. 

Trinitro-3-methyl-diphenylamine or N-(2, 4 -DinitrophenylJ-4-nitro-m-toluidine, (0aN)aC6H3.NH.C8H3(CH3).N02 red prisms mp l7l-2c(from AcOH). Was obtained after a mixt of l-chloro-2,4-dinitrobenzene, 6-nitro-m-col ui dine and anhydrous AcONa had been heated for an hr at 190°... 

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