Nitrobenzene derivatives, rearrangements

Diaminodiphenyl derivatives can be obtained from appropriately substituted nitrobenzenes by a rather dated process of alkaline reduction with zinc powder/ sodium hydroxide solution, which affords hydrazobenzene. A more recent method uses a catalytic reduction process with hydrogen and specifically deactivated catalysts of precious metals. Subsequent acid-catalyzed rearrangement with hydrochloric acid yields the hydrochloride of the target diamine ... 

Knipe et al. (1976) reported that N-(2-hydroxyethyl)-p-nitrobenzene-sulphonamides 11581 undergo a desulphonative double Smiles rearrangement in aqueous alkali (28) to produce the aniline derivative [160). Upon replacing... 

Pyrrolidone is a lactone used for the production of nylon-4. This reactant may be produced by the reduction ammoniation of maleic anhydride. s-Caprolactam, used in the production of nylon-6, may be produced by the Beckman rearrangement of cyclohexanone oxime (structure 17.11). The oxime may be produced by the catalytic hydrogenation of nitrobenzene, the photolytic nitrosylation of cyclohexane (structure 17.9), or the reaction of cyclohexanone and hydroxylamine (structure 17.10). Nearly one-half of the production of caprolactam is derived from phenol. 

Triphenyl-pyrylium salts and ring substituted phenylnitromethane derivatives similarly rearrange to the phenols 6 or nitrobenzenes 7. When the ringsubstituted phenylnitromethane is reacted with the 2,4,6-arylated pyrylium salt in t-butanol with one mole of potassium t-butylate, 5 is the suspected intermediate. It rearranges to the phenol 6 when heated in 1,2-dichlorobenzene with one mole of ethyl-diisopropylamine and to the nitro compound 7 with an excess of potassium t-butylation in t-butanol (47-81 % yield l38). Some similar examples are shown in Table 1. 

A few instances of A-acylation are also known. 6-Chloro-3(2.H)-pyridazinone reacts preferentially on the nitrogen with chloro-carbonates and the structure of the products has been assigned on the basis of IR data. A-Acylations of maleic hydrazide are claimed to proceed with unsaturated acid chlorides in nitrobenzene at 160° or with chloromethylsulfonyl chloride. The acetylated 4-methyl analog of maleic hydrazide has been also assigned as the A-acyl derivative on the basis of spectroscopic evidence. Finally, N-acylated maleic hydrazides result from the rearrangement of the corresponding acylated A-aminomaleimides. ... 

The highly carcinogenic benzidine, 4,4/-diaminobiphenyl (31b), was formerly made by reduction of nitrobenzene to hydrazobenzene, with subsequent rearrangement. Similar methods are used to prepare substituted benzidines that are believed to be non-mutagenic and non-carcinogenic. The 3,3 -dichloro derivative is a suspected carcinogen. 

A novel attempt for the better utilization of the normal pulse polaro-graphic method in the study of follow-up reaction kinetics has been proposed by Kim [117], This technique is based on symmetry analysis of the first and higher-order derivative NP polarographic curves. Reversible electron transfer coupled with a first-order irreversible following reaction (ECirr mechanism) was assumed. Significant effects were expected for fast chemical steps. This supposition is true for benzidine rearrangement in the course of the reduction of nitrobenzene [18, 116, 117]. 

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