Nitro-aniline reactions

Only the mono-amines are described here. The diamines are more frequently encountered as reduction products of dinitrobenzenes and nitro-anilines, and the chief reactions of the phenylenediamines are therefore given in Section 23, pp. 384-388. 

Nitrophenylarsonic acid has been prepared by heating p-nitrobenzenediazonium chloride with arsenious acid in hydrochloric acid, by the action of -nitrobenzenediazonium chloride on sodium arsenite, by the action of sodium arsenite on sodium -nitrobenzeneisodiazo oxide, by the diazotization of -nitro-aniline in acetic acid in the presence of arsenic chloride and cuprous chloride, and by the reaction of -nitrobenzenediazonium borofluoride with sodium arsenite in the presence of cuprous chloride. ... 

X 10mol/L). Both experiments were conducted at 25 °C. The decomposition rate of 4-nitro-aniline was very high by the photo-Fenton reaction in comparison to titanium dioxide-UV light (k = 365 nm). Decomposition products identified in both reactions were nitrobenzene, p-benzoquinone, hydroquinone, oxalic acid, and resorcinol. Oxalic acid, hydroquinone, and p-benzoquinone were identified as intermediate products using HPLC. 

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). 

Amidine derivatives are effective dehalogenation inhibitors for the chemoselective hydrogenation of aromatic halonitro compounds with Raney nickel catalysts. The best modifiers are unsubstituted or N-alkyl substituted formamidine acetates and dicyandiamide which are able to prevent dehalogenation even of very sensitive substrates. Our results indicate that the dehalogenation occurs after the nitro group has been completely reduced i.e. as a consecutive reaction from the halogenated aniline. A possible explanation for these observations is the competitive adsorption between haloaniline, nitro compound, reaction intermediates and/or modifier. The measurement of the catalyst potential can be used to determine the endpoint of the desired nitro reduction very accurately. 

Exothermic decomposition of 2-nitroaniline in chemical processes was studied by DSC and ARC techniques. The stability in reaction mixtures was markedly less than for the pure, isolated compound [1]. Later calorimetric study of pyrolysis of 2-nitro-aniline in presence of ammonium chloride showed apparent activation energy greater than 200 kJ/mol but reaction enthalpy above 2.1 kJ/g. Maximum rate of pressure rise was 200 bar/min and temperature 400°C/min [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"... 

The need for an oxidant is shown by the failure of the colour to develop if insufficient m-dinitrobenzene is used [202], although addition of a substance like lead dioxide causes rapid appearance of colour in such a mixture [igg]- w-Nitro-aniline is always formed in reactions using excess of m dinitrobenzene as the oxidant [203]. It is uncertain at present whether the abstraction of hydride ion and proton occurs as a synchronous termolecular process, or as two discrete steps in one order or the other. 

These same workers accomplished the synthesis of the radioactive XX as follows. Sodium nitrite (38.2 mg, 0.553 mmole) in 0.17 ml of water was added dropwise to a solution of 34.4 mg of ( H)-m-nitro-aniline and 30.9 mg of carrier m-nitroaniline in 0.5 ml of 50 % fluoroboric acid and 0.25 ml of water. The reaction mixture was stirred magnetically during the addition and for an additional 1 hr. After the product precipitated as a cream solid, it was filtered and washed successively with ice cold 25 % fluoroboric acid, anhydrous ethanol and anhydrous ether. The product could be recrystallized as white needles from acetone-ether if the temperature did not exceed 50°C. The yield was 39.3 mg specific activity was 7.72 x 10 dpm//imole. The product can be stored at — 20°C in 0.01 M hydrochloric acid at a concentration of 2x10 M. 

Problems may also occur during the installation of the nosyl moiety during the reaction of a primary amine 1 and nosyl chloride 2c.2b A cyclic Meisenheimer complex 39 is formed followed by loss of S02 to give nitro aniline 40 as a minor product during nosylation. None of this side product is observed with the less reactive mono-nitro... 

Preparation of m-nitrophenol from m-nitroaniline 557 A cold mixture of water (450 ml and concentrated sulfuric acid (330 ml) is poured, with stirring, over finely powdered ra-nitro-aniline (210 g), and ice (800 g) is added. When the mixture has become homogeneous, a solution of sodium nitrite (105 g) in water (250 ml) is run in during 8-10 min from a dropping funnel until the starch-iodine reaction remains positive. The temperature is kept between 0° and 5° and the mixture is stirred for a further 5-10 min. Then the m-nitrobenzenediazonium sulfate is allowed to settle, the supernatant liquid is poured off and the solid washed, if necessary, with water by decantation in order to purify the salt filtration is necessary only when gross impurity is present. 

The optimum temperature for simple arylamines is 0-2°, for m-haloaryl-amines 0-5°, and for benzidines, naphthylamines, and o- and / -haloarylamines 10-12°. In isolated cases higher temperatures are used, e.g., 34° for / -nitro-aniline and 40° for o-anisidine. The end-point of the reaction is determined by testing for an excess of nitrous acid with potassium iodide-starch paper. Amino sulfonic acids are no longer used to remove the excess of nitrous acid since they react with reactive diazo compounds.244... 

Toward the end of the run, the reaction slows down, and it is necessary to introduce steam to carry on and complete the reduction. The test for soluble iron also becomes less distinct. As long as there is any p-nitro- aniline present, a yellow spot test will be obtained on filter paper. p-Phen-ylcnediamine yields a purple spot with a perfectly clear ring around the sludge spot. It is always advisable to test for soluble iron with sodium sulfide to ensure completeness of reduction. If the reduction is not carried on at the boiling temperature, intermediate azo and hydrazo products are sure to be formed. These are not so easily reduced and cause a lowering of the yield. 

The structure of dehydro-L-ascorbic acid bisphenylhydrazide has been shown to be (36) by i.r. and u.v. studies. The rate of acid-catalysed elimination ofp-nitro-aniline from p-nitrophenylhydrazones in aqueous and non-aqueous media has been studied in connection with osazone formation. The rate of reaction is proportional to the concentration of acid and the p-nitro-group tends to retard the reaction. Higher yields of osazones are obtained in non-aqueous media. ... 

Frequently, they form condensation products. 3,4-Dichloroaniline may be transformed into 3,3, 4,4 -tetrachloro-azobenzene [239-246] and different monodiloro- and dichloroanilines are oxidised to dichloro- and tetrachloroazobenzenes [242,243]. An aniline oxidase and a peroxidase from the fungus Geotrichum candidum could dimerize different anilines except nitro anilines [244]. Condensation may transform anilines into nitroso benzenes [245]. Acetylation is an other reaction involved in the... 

In this method, an artificial substrate, L-y-glutamyl-3-carboxy-4-nitroanilide (y-GCNA), and glycylglycine (GG) are used as the donor and acceptor, respectively. Since the product of the reaction, 3-carboxy-4-nitro-aniline (CNA), has an absorption maximum at 380 nm and y-GCNA does not absorb above 410 nm, the activity, which is directly proportional to the amount of CNA liberated per unit time, is measured by monitoring the increase in absorbance at 410 nm. 

In the field of catalysis, Au NPs appear to be particularly important as an efficient catalyst in organic reactions it can offer the most favourable combination of activity and selectivity in various catalytic reactions such as electrocatalysis, redox catalysis, carbon-carbon bond formation, and photocatalytic reactions. Moreover, recent literature reported that the Au NPs-graphene composites exhibit unprecedented catalytic activity for CO oxidation, reduction of nitro-aniline and Suzuki-Miyaura coupling reaction of chlorobenzene with arylboronic acid. 

---