2.4- Dinitrochlorobenzene, reaction with

From the standpoint of geometrical considerations, the major difference is in the far greater steric requirements of the nitro group. This could result in either primary or secondary steric effects. Nevertheless, primary steric effects do not seem to be necessarily distinguishable by direct kinetic comparison. A classic example is the puzzling similarity of the activation parameters of 2-chloropyrimidine and 2,6-dinitrochlorobenzene (reaction with piperidine in ethanol), which has been described by Chapman and Rees as fortuitous. However, that nitro groups do cause (retarding) primary steric effects has been neatly shown at peri positions in the reaction with alkoxides (see Section IV,C, l,c). 

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 Zincke reaction has also been adapted for the solid phase. Dupas et al. prepared NADH-model precursors 58, immobilized on silica, by reaction of bound amino functions 57 with Zincke salt 8 (Scheme 8.4.19) for subsequent reduction to the 1,4-dihydropyridines with sodium dithionite. Earlier, Ise and co-workers utilized the Zincke reaction to prepare catalytic polyelectrolytes, starting from poly(4-vinylpyridine). Formation of Zincke salts at pyridine positions within the polymer was achieved by reaction with 2,4-dinitrochlorobenzene, and these sites were then functionalized with various amines. The resulting polymers showed catalytic activity in ester hydrolysis. ... 

Marazano and co-workers have used the Zincke reaction extensively to prepare chiral templates for elaboration to substituted piperidine and tetrahydropyridine natural products and medicinal agents. For example, 3-picoline was converted to Zincke salt 40 by reaction with 2,4-dinitrochlorobenzene in refluxing acetone, and treatment with R- -)-phenylglycinol in refluxing n-butanol generated the chiral pyridinium 77. Reduction to... 

Salt effects on the reaction of 2,4-dinitrochlorobenzene with amines or alkoxides have been investigated.Reinheimer et al. have studied decelerative ion pairing of alkali metal methoxides in reaction with this substrate cations and anions in added salts have specific effects on ion pairing. 

Variations of first-order rate constants by the hydroxyethyl amphiphile, (C8H17)3 N+CH2CH2OH MsO +NaOH are shown in Fig. 7 for variation of [amphiphile]. The curves are calculated in terms of the distribution of substrate between water and the aggregate. Similar observations were made for reaction with 2,4-dinitrochlorobenzene. The reaction rates depend also on the extent of deprotonation of the hydroxyethyl group (26) and the variation of rate constant with [NaOH] is shown in Fig. 8. The curves are calculated in terms of the binding of the substrate and deprotonation of the hydroxyl group (Biresaw et al., 1984). 

The SjvAr reactions with amines in chloroform show a peculiar behaviour and the rates cannot usually be correlated with reactions in other solvents. It has been observed in the reaction of 2,4-dinitrochlorobenzene with piperidine480 and in the reaction of 1,2-DNB with butylamine115 that chloroform exerts a special solvent effect due to its known hydrogen-bond donor ability. Thus, an association between the solvent and the nucleophile can be postulated as a side-reaction to the S Ar115. Associations of chloroform with amines are known122 and the assumption of a partial association between piperidine or butylamine and chloroform as the cause of the downward curvature in the plots of k vs [amine] seems plausible. 

For thiols a similar procedure is investigated as with aldehydes. One possibility is absorption of thiols in an alkaline solution and reaction with 2,4-dinitrochlorobenzene,... 

Dinitrochlorobenzene (95) reacts with pyridine to form 2,4-dinitrophenylpyridinium chloride (103), a reactive intermediate which readily reacts with a variety of nucleophiles. The reaction of (103) with hydrogen sulfide yields 2,2, 4,4 -tetranitrodiphenylsulfide (104), which on nitration-oxidation with fuming nitric acid, yields 2,2, 4,4, 6,6 -hexanitrodiphenylsulfoxide (105). The sulfide (104) is also formed from the reaction of two equivalents of 2,4-dinitrochlorobenzene (95) with sodium thiosulfate or sodium disulfide in aqueous ethanol. ... 

Amine 212 was also coupled with peptides [233], acetic anhydride [215, 234], dinitrobenzoyl chloride [235] or a ferrocene carboxylic add chloride [215, 236] in good yields. Reaction with dinitrochlorobenzene [237] or dinitrofluorobenzene... 

Reaction with 2,4-dinitrochlorobenzene and potassium acetate yields 2,4-dinitrophenylhydrazine ... 

Mercaptobenzo[6]thiophenes are readily characterized through the formation of benzo[6]thienyl 2,4-dinitrophenyl sulfides by reaction with 2,4-dinitrochlorobenzene in the presence of base. 2-506,700 and 3-mercaptobenzo[6]thiophene505 are readily oxidized to the corresponding disulfides (e.g., with nitric acid). 

Much of the development in this field is traceable to two quite different original interests. The first goes back to Ullmann and Nddai s observation27 that the p-toluenesulfonate of 2,4-dinitrophenol, like 2,4-dinitrochlorobenzene, reacts with amines these cause desulfonyloxyla-tion. For example, with aniline, the following reaction occurred ... 

Dinitrochlorobenzene. Strongly exothermic reaction with 2,4-dinitrochlorobenzene.3 Mercuric Oxide. Dropwise addition to mercuric oxide may result in an explosion.2,4 Sodium. Dropwise addition to a suspension of Na in ether and heating forms sodium hydrazide, which explodes in air reacts very exothermally with Na with the liberation of H2 and NH3.5... 

Catalytic action of cationic surfactants (quaternary pyridinium chlorides) in the hydrolysis of 2,4-dinitrochlorobenzene and in the reaction with aniline in a foam has been observed as well [109,110]. For example, in the presence of quaternary pyridinium bases, the rate constant of the hydrolysis in a foam increased from 1.4210 7 (without the surfactant) to 2.7 1 O 2 m3 mol 1 s 1 (with surfactant) which is greater than in the case of catalysis in micelles (8.3-10 6 m3 mol 1 s"1). A similar acceleration of acid hydrolysis occurs also in the presence of anionic surfactants [112,113]. 

In accordance with this expectation, the reaction of diaminocyclopropenethione with dimethyl phosphite affords the diaminomethyl-thiocyclopropenium ion (38) (Eq. 21). This cation is also obtained by reaction with other methylating agents (e.g. CH3I). The diaminothio-cyclopropenium ion (39), shown in Eq. 22, is obtained by the attack of 2,4-dinitrochlorobenzene on diamino-cyclopropenethione. 

Manufacture (1) Chlorobenzene is nitrated with a mixture of sulphuric acid and nitric acid to produce dinitrochlorobenzene, which is synthesized to dinitro-sodium phenolate under reaction with sodium hydroxide. This is further changed to dinitrophenol with hydrochloric acid and then the dinitrophenol is nitrated by a mixture of sulphuric acid and nitric acid to trinitrophenol5 picric acid. (2) Phenol is mixed with cone, sulphuric acid and heated to obtain phenol-sulphonic acid. This is nitrated with a mixture of sulphuric acid and nitric acid to trinitrophenol. 

The increased resonance effect due to the presence of two nitro groups at both ortho positions and combined resonance and inductive effects enforced by one nitro and one halogen atom activate the Smiles rearrangement as well as the ring closure to such an extent that both processes take place instantaneously. However, the resonance elfect in 2,4-dinitrochlorobenzene is not so pronounced and its reaction with 2-aminobenzenethiol does not go in one step (88MI1). 

---