Orthanilic acid

In a 600 ml. bolt-head Bask, provided with a mechanical stirrer, place 70 ml. of oleum (20 per cent. SO3) and heat it in an oil bath to 70. By means of a separatory funnel, supported so that the stem is just above the surface of the acid, introduce 41 g. (34 ml.) of nitrobenzene slowly and at such a rate that the temperature of the well-stirred mixture does not rise above 100-105°. When all the nitrobenzene has been introduced, continue the heating at 110-115° for 30 minutes. Remove a test portion and add it to the excess of water. If the odour of nitrobenzene is still apparent, add a further 10 ml. of fuming sulphuric acid, and heat at 110-116° for 15 minutes the reaction mixture should then be free from nitrobenzene. Allow the mixture to cool and pour it with good mechanical stirring on to 200 g. of finely-crushed ice contained in a beaker. All the nitrobenzenesulphonic acid passes into solution if a little sulphone is present, remove this by filtration. Stir the solution mechanically and add 70 g. of sodium chloride in small portions the sodium salt of m-nitro-benzenesulphonic acid separates as a pasty mass. Continue the stirring for about 30 minutes, allow to stand overnight, filter and press the cake well. The latter will retain sufficient acid to render unnecessary the addition of acid in the subsequent reduction with iron. Spread upon filter paper to dry partially. 

Place 84 g. of iron filings and 340 ml. of water in a 1 5 or 2-litre bolt-head flask equipped with a mechanical stirrer. Heat the mixture to boiling, stir mechanically, and add the sodium m-nitrobenzenesulphonate in small portions during 1 hour. After each addition the mixture foams extensively a wet cloth should be applied to the neck of the flask if the mixture tends to froth over the sides. Replace from time to time the water which has evaporated so that the volume is approximately constant. When all the sodium salt has been introduced, bod the mixtoie for 20 minutes. Place a small drop of the suspension upon filter paper and observe the colour of the spot it should be a pale brown but not deep brown or deep yellow. If it is not appreciably coloured, add anhydrous sodium carbonate cautiously, stirring the mixture, until red litmus paper is turned blue and a test drop upon filter paper is not blackened by sodium sulphide solution. Filter at the pump and wash well with hot water. Concentrate the filtrate to about 200 ml., acidify with concentrated hydrochloric acid to Congo red, and allow to cool. Filter off the metanilic acid and dry upon filter paper. A further small quantity may be obtained by concentrating the mother liquid. The yield is 55 g. 

Primary aromatic amines differ from primary aliphatic amines in their reaction with nitrous acid. Whereas the latter yield the corresponding alcohols (RNHj — - ROH) without formation of intermediate products see Section 111,123, test (i), primary aromatic amines yield diazonium salts. Thus aniline gives phcnyldiazonium chloride (sometimes termed benzene-diazonium chloride) CjHjNj r +C1 the exact mode of formation is not known, but a possible route is through the phenylnitrosoamraonium ion thus  

Phenyldiazonium chloride and other similar diazonium compounds are very soluble in water, are completely insoluble in ether and other organic solvents, and are completely dissociated in aqueous solution to organic cations and inorganic anions e.g., chloride ions) a convenient formulation is therefore, for example, C HjjNj+CP. 

The experimental conditions necessary for the preparation of a solution of a diazonium salt, dlazotisation of a primary amine, are as follows. The amine is dissolved in a suitable volume of water containing 2-5-3 equivalents of hydrochloric acid (or of sulphuric acid) by the application of heat if necessary, and the solution is cooled in ice when the amine hy drochloride (or sulphate) usually crystallises. The temperature is maintained at 0-5°, an aqueous solution of sodium nitrite is added portion-wise until, after allowing 3-4 minutes for reaction, the solution gives an immediate positive test for excess of nitrous acid with an external indicator—moist potassium iodide - starch paper f  

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Bake sulfonation is an important variant of the normal sulfonation procedure. The reaction is restricted to aromatic amines, the sulfate salts of which ate prepared and heated (dry) at a temperature of approximately 200°C in vacuo. The sulfonic acid group migrates to the ortho or para positions of the amine to give a mixture of orthanilic acid [88-21-1] and sulfanilic acid [121 -57-3] respectively. This tendency is also apparent in polynuclear systems so that 1-naphthylamine gives 1-naphthy1amine-4-su1fonic acid. 

It has been observed2 that the dropwise addition of an aqueous solution of potassium ethyl xanthate to a cold (0°) aqueous solution of diazotized orthanilic acid results in the immediate loss of nitrogen when a trace of nickel ion is present in the stirred diazonium solution.3 The catalyst can be added as nickelous chloride or simply by using a nichrome wire stirrer. When no nickel ion is added and a glass stirrer is employed, the diazonium xanthate precipitates and requires heat (32°) to effect decomposition. 

Jahnke M, T El-Banna, R Klintworth, G Auling (1990) Mineralization of orthanilic acid is a plasmid-associated trait in Alcaligenes sp. 0-1. J Gen Microbiol 136 2241-2249. 

Oleoxyl chloride, ol3 Oleyl alcohol, ol2 Oleylamine, o9 o-Orthanilic acid, al 15 7-Oxabicyclo[2.2.1]heptane, c331b, e7 7-Oxabicyclo[4.1.0]heptane, e6 6-Oxabicyclo[3.1.0]hexane, elO Oxacyclopentane, t69... 

Bluish red reactive dyes are almost totally dominated by H acid as the indispensable coupling component. Various mono- or disulphonated anilines or naphthylamines are suitable diazo components, but the outstandingly important one is orthanilic acid (7.96). As with orange and scarlet dyes, haloheterocyclic (Z) reactive systems are linked via the imino group of the H acid residue but sulphatoethylsulphone substituents are found in the diazo component with N-acetyl H acid as the typical coupler. A characteristic problem associated with reactive dyes derived from H acid is their accelerated fading under the simultaneous influence of perspiration and light (section 3.3.4). 

Unmetallised disazo dyes of the type A—>M—>E in Winther symbols (section 4.7) dominate this sector. The A component is usually a disulphonated aniline or naphthylamine. Orthanilic acid or p-xylidine (2,5-dimethylaniline) for yellow browns, or a variety of monosulphonated 1-naphthylamines for redder browns, are selected as the M and E components. The terminal amino group provides the site for attachment of the reactive... 

Orthanilic acid (2-aminobenzenesulphonic acid) [88-21-1] M 173.2, m >300 (dec). Crystd from aqueous soln, containing 20ml of cone HCl per L, then crystd from distilled water. 

Aminobenzenesulphonic acid (orthanilic acid, Expt 6.64) is readily prepared by the reduction of 2-nitrobenzenesulphonic acid. The latter may be prepared by the hydrolysis of the corresponding sulphonyl chloride which is obtained from di-o-nitrophenyl disulphide. The preparation of this disulphide involves the use of the reactive aryl halide, 2-chloronitrobenzene (cf. Expts 6.93... 

Solutions of orthanilic acid, when chilled below 13.50, yield the hydrated form of the acid, which crystallizes as needles (see photographs in the paper by Fierz and others).1... 

Orthanilic acid was first made by the reduction of nitro-benzenesulfonic acid by ammonium sulfide.2 This reduction has also been carried out electrolyticallv, and by the use of iron or zinc.3 The acid has also been made by the rearrangement of phenylsulfamic acid,4 by the action of sodium hypobromite upon potassium o-carbaminebenzenesulfonate,5 by the reduction of the mixed nitrobenzenesulfonic acids followed by separation of the isomers,6 by the action of methyl alcohol upon o-nitro-phenylsulfurchloride,7 by the action of acid upon diacetyl diphenylsulfamide,8 by the debromination of />-bromoaniline-e-sulfonic acid,9 by the reduction of 1,2,6-aminothiophenolsulfonic acid,10 and by the hydrolysis and reduction of e-nitrobenzene-sulfonyl chloride, which was obtained from di-o-nitrophenyl-disulfide.11... 

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