O-Nitro aniline

B. Benzofurazan oxide. A mixture of 21 g. (0.32 mole) of potassium hydroxide and 250 ml. of 95% ethanol in a 1-1. Erlenmeyer flask is heated on a steam bath until the solid dissolves (Note 1). o-Nitro-aniline (40 g., 0.29 mole) (Note 2) is dissolved in the warm alkali solution. The resulting deep red solution is then cooled to 0°, and the sodium hypochlorite solution from part A is added slowly with good stirring over the course of 10 minutes (Note 3). The flocculent yellow precipitate is collected on a large Buchner funnel, washed with 200 ml. of water, and air-dried. The crude product weighs 36.0-36.5 g. and melts at 66-71° (Note 4). The product is purified by recrystallization from a solution made up from 45 ml. of 95% ethanol and 15 ml. of water. Material insoluble in the hot solvent is removed by filtration, and the hot filtrate is allowed to cool to room temperature. The yield of yellow benzofurazan oxide is 31.6-32.5 g. (80-82%), m.p. 72-73°. 

Aus 2,5-Diamino-l-nitro-benzol126, Essigsaure-(2-amino-3-nitro-anilid)126 und 4-Amino-3-ni-tro-phenol127 wurden nach der Hypohalogenit-Methode keine Benzofurazan-1-oxide crhaltcn. Folgende O-Nitro-aniline liefern dagegen die entsprechenden Furazan-l-oxide ... 

N,N -Bis(2-nitrophenyl)-formamidine, O2N.C6H4.N CH.NH.C6H4.N02, ndls, mp 160— 61°[Beil, 124—25°, Ref l] was prepd by interaction of P pentachloride in a chlf medium upon o-nitioformamide o-nitro-aniline (Refs 1, 5, 7 9)... 

Our approach was based on the observation that it is possible to perform SwAr reactions on solid support with amino acids using a solvent system comprised, in equal parts, of acetone and an aqueous 0.5 M NaHC03 solution at temperatures around 70-75°C. Application of this solvent system to the synthesis of quinoxalin-2-ones 6 from la and a-amino acids is described in Section 3.3.2. With respect to the synthesis of 1,5-ben-zodiazepin-2-ones 4, more than 40 examples of aliphatic and aromatic P-amino acids 35 were found to furnish the desired o-nitro anilines 36, about 80% of which were successfully carried on to eventually afford the ben-zodiazepinone products 4 (Scheme 6). In general, the anthranilic acids required slightly harsher conditions to drive the fluorine displacement to completion (75-80°C, 72 h vs. 70-75°C, 24 h for aliphatic P-amino acids). 

The thermal cyclization of o-nitro- -anilines is considerably facilitated by the presence of mineral acid, when the cyclization proceeds at temperatures sufficiently low to allow the isolation of the... 

The effect of a Lewis acid on the o-nitro-(-aniline system is well illustrated by the unexpected result from the attempted Friedel-Crafts acetylation of these compounds. In 1926, van Romburgh and co-workers51,52 observed that the action of acetic anhydride and zinc chloride on the o-nitrodimethylaniline (111) did not give the acetylated product (112), but instead the benzimidazolone (113). Even more surprising was their alleged observation that the same reagents converted the diethyl compound (114) into the quinoxaline... 

In a 3-I. round-bottom flask fitted with a reflux condenser are placed 218 g. (1 mole) of coarsely powdered technical o-nitro-aniline-/>-sulfonic acid, and a hot mixture of 775 cc. of concentrated sulfuric acid (sp. gr. 1.84) and 950 cc. of water (Note 1). Heat is applied and the mixture is refluxed gently for. an hour after solution is practically complete (total about three hours). The resulting dark solution is allowed to cool and is poured slowly into 12 1. of cold water in a crock (Note 2). 

H.H. Hodgson, Chem Ind 1945, 362 described explosive reactions of diazonium c ompd with sulfides of sodium. He claimed that he prepd as early as 1918 a brilliant red solid which exploded violently on rubbing with a glass rod, when he treated diaxotized o-nitro-aniline with N disulfide. He also listed several later refs in which expl reactions betn diazotized compd and sulfides were reported. Some of these expl products were known in USA as "explosive diazo-sulfides"... 

To a solution of 9 2 grams of mercuric acetate in 15 c.c. of water containing a few drops of acetic acid, a solution of 4-T grams of o-nitro-aniline in 60 c.c. of alcohol is added, and the mixture boiled for one hour. The liquid is filtered whilst hot, and on cooling the compound separates. It is recrystallised from alcohol containing a little acetic acid, yellow crystals being deposited. It does not melt at 300° C., but turns red very gradually. It is stable towards ammonium sulphide. 

The cyclization of the above nitro compounds to benzimidazoles is also observed thermally.37 Indeed, the mass spectra of o-nitro-(-anilines reveal the thermal cyclization to benzimidazoles in the probe.32 Analogous interactions of o-nitro groups in the mass spectrometer are well known.38... 

Because of refractive-index effects, an unretained solvent used to dissolve the sample— if different from the chromatographic mobile phase—often deflects the base-line when passing through an ultraviolet detector cell. This indicates the void volume or the void time. Consider the chromatogram in Figure 21.19. (a) Determine the capacity factors for each nitroaniline isomer, (b) Determine the selectivity factor for the m- and p-substituted isomers relative to the o-nitro-aniline. 

An alternative pathway started with N-hydroxyalkyl-o-nitro-anilines (VIII), which were successively chlorinated with thionyl-choride and coupled with l-(a, a -diarylmethyl)-piperazine (II) to give the intermediates XV. Catalytic hydrogenation of the nitro group afforded o-phenylenediamines XVI, which could be used to synthesize either III or XIII. Cyclisation of XVI with CS2 in ethanol gave the 2-mercaptoimidazole (XVII) (10). which was methylated to XVIII with methylsulphate. On the other hand, ring closure, with methyl (a-imino-a-methoxymethyl)carbamate, gave the 2-methoxy carbonylamino derivative XIX (11). which was further hydrolyzed and then reacylated affording 2-amino (XX) and 2-acetylamino (XXI) derivatives (Scheme 5). These compounds are also summarized in Table II. 

Nucleophilic substitution of o-nitrochlorobenzene with ammonia yields o-nitro-aniline, which is used to make dyestuffs and plant protection agents as well as UV-stablizers. 

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