Azoxybenzene


When a solution of nitrobenzene in methanol is boiled with sodium hydroxide, the nitrobenzene is reduced to azoxybenzene by the methanol, which is itself oxidised to formic acid.  [c.212]

AZOXYBENZENE. Required Sodium hydroxide, 23 g. nitrobenzene, 15 ml. methanol, 120 ml.  [c.212]

Add 23 g. of powdered (or flake ) sodium hydroxide to a solution of 15 ml. (18 g.) of nitrobenzene in 120 ml. of methanol contained in a 250 ml. short-necked bolt-head flask. Fix a reflux water-condenser to the flask and boil the solution on a water-bath for 3 hours, shaking the product vigorously at intervals to ensure thorough mixing. Then fit a bent delivery-tube to the flask, and reverse the condenser for distillation, as in Fig. 59, p. 100, or Fig. 23(D), p. 45). Place the flask in the boiling water-bath (since methanol will not readily distil when heated on a water-bath) and distil off as much methanol as possible. Then pour the residual product with stirring into about 250 ml. of cold water wash out the flask with water, and then acidify the mixture with hydrochloric acid. The crude azoxybenzene separates as a heavy oil, which when thoroughly stirred soon solidifies, particularly if the mixture is cooled in ice-water.  [c.212]

Then filter off the solid azoxybenzene at the pump, wash it thoroughly with water, and drain well. Recrystallise from a minimum of m ethylated spirit, allowing the hot solution to cool spontaneously (with occasional stirring) until crystallisation starts, and then cool in ice-water. If crystallisation is delayed, seed the solution with a trace of the crude product if on the other hand the azoxybenzene separates at first as an emulsion, add methylated spirit, drop by drop, with stirring until the solution is clear, and then allow the cooling to proceed as before. The  [c.212]

AZOBENZENE, Required Azoxybenzene, 8 g., iron filings,  [c.213]

Place 8 g. of the pure powdered azoxybenzene and 25 g. of iron filings (both reagents being quite dry) in a 75 ml. distilling-flask F and mix thoroughly by shaking. Cork the flask and fit to the side-arm a boiling-tube B to act as receiver (Fig. 66) cut or file a groove G in the boiling-tube cork to allow escape of air. Now heat the mixture directly with the Bunsen flame, waving the latter around the base of the flask to ensure uniform heating heat gently at first and later more strongly. The red liquid azobenzene distils over smoothly and eventually solidifies in the receiver. When no more distillate passes over, detach the boiling-tube, and then, in order to eliminate basic impurities which are formed as byproducts in the reaction, add 20-30 ml. of dilute hydrochloric acid (i vol. of concentrated acid 2 vols. of water) which have been heated to about 70° cork the tube securely and shake the mixture, so that impurities in the molten drops of azobenzene are thoroughly extracted by the acid, which usually becomes dark in colour. Now cool in water until the globules of azobenzene solidify, and then filter at the pump. Break up the azobenzene with a spatula on the filter, wash thoroughly with water, and drain. Recrystallise from a minimum of boiling methylated spirit, filtering the hot solution through a small fluted filter-paper. The azobenzene separates as reddish-orange crystals, m.p. 67-68°. Yield, 4 g. A second recrystallisation from methylated spirit may be necessary to obtain a satisfactory melting-point.  [c.213]

Azoxybenzene is readily prepared by reduction of nitrobenzene in an alkaline medium with dextrose or sodium arsenite  [c.629]

Equip a 500 ml. three-necked flask with an efficient stirrer (e.g., a Hershberg stirrer. Fig. II, 7, 8) and a reflux condenser stopper the third neck. Place a solution of 30 g. of sodium hydroxide in 100 ml. of water, and also 20-5 g. (17-1 ml.) of pure nitrobenzene in the flask, immerse it in a water bath maintained at 55-60°, and add 21 g. of anhydrous dextrose in small portions, with continuous stirring, during 1 hour. Then heat on a boiUng water bath for 2 hours. Pour the hot mixture into a 1 litre round-bottomed flask and steam distil (Fig. II, 40, 1) to remove aniline and nitrobenzene. When the distillate is clear (i.e., after about 1 htre has been collected), pour the residue into a beaker cooled in an ice bath. The azoxybenzene soon sohdifies. Filter with suction, grind the lumps of azoxybenzene in a mortar, wash with water, and dry upon filter paper or upon a porous plate. The yield of material, m.p. 35-35-5°, is 13 g. Recrystallise from 7 ml. of rectified spirit or of methyl alcohol the m.p. is raised to 36°.  [c.631]

The azoxybenzene in turn, when heated with iron filings, readily undergoes C.H.NO NC.H. + Fe = C.H.N NC,H. + FeO further reduction to azobenzene,  [c.212]

AZOXYBENZENE. Required Sodium hydroxide, 23 g. nitrobenzene, 15 ml. methanol, 120 ml.  [c.212]

Add 23 g. of powdered (or flake ) sodium hydroxide to a solution of 15 ml. (18 g.) of nitrobenzene in 120 ml. of methanol contained in a 250 ml. short-necked bolt-head flask. Fix a reflux water-condenser to the flask and boil the solution on a water-bath for 3 hours, shaking the product vigorously at intervals to ensure thorough mixing. Then fit a bent delivery-tube to the flask, and reverse the condenser for distillation, as in Fig. 59, p. too, or Fig. 23(D), p. 45). Place the flask in the boiling water-bath (since methanol will not readily distil when heated on a water-bath) and distil off as much methanol as possible. Then pour the residual product with stirring into about 250 ml, of cold water wash out the flask with water, and then acidify the mixture with hydrochloric acid. The crude azoxybenzene separates as a heavy oil, which when thoroughly stirred soon solidifies, particularly if the mixture is cooled in ice-water.  [c.212]

Then filter oflF the solid azoxybenzene at the pump, wash it thoroughly with water, and drain well. Recrystallise from a minimum of m ethylated spirit, allowing the hot solution to cool spontaneously (with occasional stirring) until crystallisation starts, and then cool in ice-water. If crystallisation is delayed, seed the solution with a trace of the crude product if on the other hand the azoxybenzene separates at first as an emulsion, add methylated spirit, drop by drop, with stirring until the solution is clear, and then allow the cooling to proceed as before. The  [c.212]

AZOBENZENE. Required Azoxybenzene, 8 g. iron filings, 25 g-  [c.213]

Place 8 g. of the pure powdered azoxybenzene and 25 g. of iron filings (both reagents being quite dry) in a 75 ml. dis-tilling-flask F and mix thoroughly by shaking. Cork the flask and fit to the side-arm a boiling-tube B to act as receiver (Fig. 66) cut or file a groove G in the boiling-tube cork to allow escape of air. Now heat the mixture directly with the Bunsen flame, waving the latter around the base of the flask to ensure uniform heating heat gently at first and later more strongly. The red liquid azobenzene distils over smoothly and eventually solidifies in the receiver. When no more distillate passes over, detach the boiling-tube, and then, in order to eliminate basic impurities which are formed as byproducts in the reaction, add 20-30 ml. of dilute hydrochloric acid (i vol. of concentrated acid 2 vols. of water) which have been heated to about 70° cork the tube securely and shake the mixture, so that impurities in the molten drops of azobenzene are thoroughly extracted by the acid, which usually becomes dark in colour. Now cool in water until the globules of azobenzene solidify, and then filter at the pump. Break up the azobenzene with a spatula on the filter, wash thoroughly with water, and drain. Recrystallise from a minimum of boiling methylated spirit, filtering the hot solution through a small fluted filter-paper. The azobenzene separates as reddish-orange crystals, m.p. 67-68°. Yield, 4 g. A second recrystallisation from methylated spirit may be necessary to obtain a satisfactory melting-point.  [c.213]

Azoxybenzene Buffer+20% EtOH, pH 6.3 -0.30  [c.982]

Further nitration gives w-dinilrobenzene sulphonation gives w-nitrobenzene sulphonic acid. Reduction gives first azoxybenzene, then azobenzene and aniline depending upon the conditions. Used in the dyestufTs industry as such or as aniline.  [c.277]

N-phenylhydroxylamine, PhNHOH and further reduction can give azoxybenzene, azobenzene, hydrazobenzene and aniline. The most important outlet commercially for the nitro-compounds is the complete reduction to the amines for conversion to dyestufTs. This is usually done in one stage with iron and a small amount of hydrochloric acid.  [c.277]

The azoxybenzene in turn, when heated with iron filings, readily undergoes C4HjNO NC,Hs + Fe = C.HjNtNC.Hs + FeO further reduction to azobenzene.  [c.212]

When a solution ofnitrobenaene in methanol is boiled with sodium hydroxide, the nitrobenzene is reduced to azoxybenzene by the methanol, which is itself oxidised to formic acid.  [c.212]

The reduction of the nitro group to yield aniline is the most commercially important reaction of nitrobenzene. Usually the reaction is carried out by the catalytic hydrogenation of nitrobenzene, either in the gas phase or in solution, or by using iron borings and dilute hydrochloric acid (the Bechamp process). Depending on the conditions, the reduction of nitrobenzene can lead to a variety of products. The series of reduction products is shown in Figure 1 (see Amines byreduction). Nitrosobenzene, /V-pbenylbydroxylamine, and aniline are primary reduction products. Azoxybenzene is formed by the condensation of nitrosobenzene and /V-pbenylbydroxylamine in alkaline solutions, and azoxybenzene can be reduced to form azobenzene and hydrazobenzene. The reduction products of nitrobenzene under various conditions ate given in Table 2.  [c.63]

Fig. 1. Reduction products of nitrobenzene (1) nitrosobenzene [98-95-3] (2) /V-pbenylbydroxyl amine [100-65-2] (3) aniline [62-53-3] (4) azoxybenzene Fig. 1. Reduction products of nitrobenzene (1) nitrosobenzene [98-95-3] (2) /V-pbenylbydroxyl amine [100-65-2] (3) aniline [62-53-3] (4) azoxybenzene

See pages that mention the term Azoxybenzene : [c.210]    [c.212]    [c.213]    [c.213]    [c.522]    [c.556]    [c.628]    [c.628]    [c.628]    [c.631]    [c.1085]    [c.1122]    [c.210]    [c.212]    [c.213]    [c.213]    [c.522]    [c.558]    [c.29]    [c.283]    [c.583]    [c.83]    [c.64]   
See chapters in:

Textbook on organic chemistry  -> Azoxybenzene

Practical organic chemistry  -> Azoxybenzene


Textbook on organic chemistry (1974) -- [ c.629 , c.631 ]

Organic syntheses Aceto-p-cymene (1934) -- [ c.11 , c.16 ]

Organic syntheses Aconitic Acid (1937) -- [ c.11 , c.16 , c.17 , c.95 ]