Diazoaminobenzene

of water, and add the solution to the mixture. At the end of half an hour, add about 300 cc. of water, stir, and filter by suction wash the precipitate with cold water. Press the diazoaminobenzene on a porous plate, and let it stand until dry do not heat it. Weigh the product and calculate the percentage yield. 

Crystallize a little of the compound from petroleum ether as follows Digest for 2 or 3 minutes 2 grams of the diazoamino- 

Diazoaminobenzene crystallizes in yellow plates, which melt at 98° it explodes when heated above its melting-point. It is insoluble in water, and is soluble in benzene, ether, and alcohol. The yield obtained in the above preparation is about 15 grams. 

—The sodium acetate is added to interact with the excess of hydrochloric acid present  

The salt is frequently added to solutions containing strong acids when it is desired to bring about a reaction which does not take place in the presence of such acids. 

5-10 minutes. Allow to stand with firequent shaking (1) for 15 minutes, and add a solution of 21 0 g. of crystallised sodium acetate in 40 ml. of water during 5 minutes. A yellow precipitate of diazoaminobenzene begins to form immediately allow to stand with frequent shaMng for 45 minutes and do not allow the temperature to rise above 20° (add ice, 

In a 250 ml. flask place 75 ml. of water, 24 g. (20 ml.) of concentrated hydrochloric acid and 14g. (13-7 ml.) of aniline. Shake vigorously (1) and then add 50 g. of crushed ice. Rim in a solution of 5-2 g. of sodium nitrite in 12 ml. of water, with constant shaking, during a period of 5-10 minutes. Allow to stand with frequent shaking (1) for 15 minutes, and add a solution of 21 0 g. of crystallised sodium acetate in 40 ml. of water during 5 minutes. A yellow precipitate of diazoaminobenzene begins to form immediately allow to stand with frequent shaking for 45 minutes and do not allow the temperature to rise above 20° (add ice, 

The temperature noted is not known to be the maximum temperature at which the reaction may be run. 

A rubber dam is fitted over the top of the Buchner funnel and held in place by rubber bands in order to remove as much of the water as possible. 

An additional crop of crystals weighing 20-25 S melting at 79-83 ° can be obtained by evaporating the mother liquors to I 1. and chilling in an ice bath. 

The size of the run may be halved an actual run with half quantities gave 125 g. 

Diazoaminobenzene has been prepared by the action of sodium nitrite on aniline sulfate by the action of sodium nitrite on aniline hydrochloride by the action of sodium nitrite and sodium acetate on aniline hydrochloride by the action of ammonium nitrate and hydrogen sulfide on aniline hydrochloride in the presence of iron and by the action of amyl nitrite on aniline.  

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It is prepared by an intramolecular transformation of diazoaminobenzene in the presence of aniline hydrochloride, or in one stage by diazotizing a solution of aniline and aniline hydrochloride with an insufficient amount of nitrous acid. 

Sufficient sodium nitrite must be added to diazotise all the aniline present, otherwise the unchanged aniline will react with the diazonium chloride to give diazoaminobenzene (p. 187) ... 

Diazonium salts couple readily with aromatic primary amines, giving diazoamino compounds. If for instance an aqueous solution of aniline sulphate is diazotised with a deficiency of nitrous acid, only part of it is converted into benzenediazonium sulphate and the latter then couples with the unchanged aniline to give diazoaminobenzene. The reaction is carried out at the opti-CeHsNHj.HjSO + HONO = CbHsNjHSO, + zHaO... 

The recrystallisation of diazoaminobenzene has to be performed with care, as the substance is freely soluble in most liquids and tends moreover to decompose if its solution is not rapidly cooled. Place 2 g. of the crude, freshly prepared, well-drained material in a boiling-tube, add about 15-20 ml. of ethanol and 1-2 drops of 10% aqueous sodium hydroxide solution, and then heat rapidly until boiling if the solution should contain insoluble impurities, filter through a small fluted paper, and at once cool the filtrate in ice-water. The diazoaminobenzene should rapidly crystallise out from the cold and stirred solution filter the crystals rapidly at the pump whilst the solution is still cold, as... 

When diazoaminobenzene is added to a warm aqueous solution of hydrochloric acid, it tends to break up into its original components, i.e., to benzene-diazonium chloride and aniline, and an equilibrium is thus established. The diazonium chloride and the aniline, however, in addition to recombining to form diazoaminobenzene. also undergo direct condensation at the p-hydro-... 

C,H5N,NHC,Hs+HC1 = C,H 5N C1+H,NC,H5- C H5N NC H NH +HC1 gen atom of the aniline molecule, giving aminoazobenzene. Since this reaction is irreversible, whilst the former is freely reversible, the final result is the complete conversion of the diazoaminobenzene into the aminoazobenzene. (The intermediate formation of the benzenediazonium chloride can be demonstrated by adding dimethylaniline, with which the diazonium chloride couples preferentially, giving dimethylaminoazobenzene, C6HsN NC6HiN(CH3)i.)... 

The conversion of the diazoaminobenzene into aminoazobenzene is promoted by the addition of aniline hydrochloride even more readily than by that of free hydrochloric acid. The aniline hydrochloride dissociates in solution giving hydrochloric acid and aniline the former promotes the formation of the above equilibrium, and the latter by increasing the active mass of the free aniline further accelerates the condensation to aminoazobenzene,... 

Add 4 g. of aniline hydrochloride to 16 ml. of aniline contained in a 100 ml. conical flask, and then add 8 g. of diazoaminobenzene, both the solid components being finely powdered. Place the flask in a water-bath, and heat the latter carefully so that the well-stirred mixture is kept at 40° for i hour. Then remove the flask from the water-bath and allow it to stand overnight to ensure that the conversion is complete. Then add about 20 ml. of glacial acetic acid dissolved in the same volume of water, and stir the mixture well to extract the free aniline in the form of its soluble acetate. Allow the mixture to stand (with occasional stirring) for at least 10 minutes, and then filter at the... 

Attention has previously (see Diazonium Sails) been drawn to the fact that unless an excess of hydrochloric (or mineral) acid is used in the diazotisation process, coupling occurs between the diazonium salt and the amine to give diazoamino compounds. Thus phenyldiazonium chloride and aniline yield diazoaminobenzene. This substance may be conveniently prepared by dissolving two equivalents of aniline in three equivalents of hydrochloric acid, and adding one equivalent of sodium nitrite in aqueous solution followed by two equivalents of sodium acetate ... 

If diazoaminobenzene is dissolved in aniline with a small quantity of aniline hydrochloride and the mixture kept at about 40° for a short time, it is converted in good yield into />-amlno-azobenzene ... 

Dissolve 5 g. of finely-powdered diazoaminobenzene (Section IV,81) in 12-15 g. of aniline in a small flask and add 2-5 g. of finely-powdered aniline hydrochloride (1). Warm the mixture, with frequent shaking, on a water bath at 40-45° for 1 hour. Allow the reaction mixture to stand for 30 minutes. Then add 15 ml. of glacial acetic acid diluted with an equal volume of water stir or shake the mixture in order to remove the excess of anihne in the form of its soluble acetate. Allow the mixture to stand, with frequent shaking, for 15 minutes filter the amino-azobenzene at the pump, wash with a little water, and dry upon filter paper Recrystallise the crude p-amino-azobenzene (3-5 g. m.p. 120°) from 15-20 ml. of carbon tetrachloride to obtain the pure compound, m.p. 125°. Alternatively, the compound may be recrystaUised from dilute alcohol, to which a few drops of concentrated ammonia solution have been added. 

Diazoaminobenzene (IV,81, 5 scale reduce periods of standing to one third). 

Diazoaminobenzene (1,3-diphenyltriazene) [136-36-6] M 197.2, m 99 . Crystd from pet ether (b 60-80°), 60% MeOH/water or 50% aqueous EtOH (charcoal) containing a small amount of KOH. Also purified by chromatography on alumina/toluene and toluene-pet ether. Stored in the dark. 

Dissolve in cold water and add a fevv drops of aniline, and shake up. Diazoaminobenzene separates out as a yellow crystalline precipitate. 

The phenylation of quinoline with dibenzoyl peroxide was studied by Pausacker, who obtained all seven monophenylated quinolines in relative amounts shown in (4).- He also examined the phenylation of pyridine-iV-oxide with diazoaminobenzene and obtained the results shown in (5). ... 

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