Anilines separation

Finally, add an excess of concentrated hydrochloric acid slowly with stirring to the alkaline filtrate remaining from the original reaction product. As the solution becomes acid, the sulphonyl-aniline separates as a thick sticky syrup which, when stirred, rapidly crystallises. Cool the mixture in ice-water if necessary, and then filter off the solid product at the pump, wash well with water, and drain. Recrystallise from a mixture of 2 volumes of ethanol and i volume of water to prevent the sulphonyl-aniline from separating as an emulsion, allow the hot solution to cool spontaneously (with occasional stirring) until crystallisation starts, and... 

Add 4 0 g. (4 0 ml.) of pure anihne dropwise to a cold solution of ethyl magnesium bromide (or iodide) prepared from 1 Og. of magnesium, 5 0 g. (3-5 ml.) of ethyl bromide (or the equivalent quantity of ethyl iodide), and 30 ml. of pure, sodium-dried ether. When the vigorous evolution of ethane has ceased, introduce 0 02 mol of the ester in 10 ml. of anhydrous ether, and warm the mixture on a water bath for 10 minutes cool. Add dilute hydrochloric acid to dissolve the magnesium compounds and excess of aniline. Separate the ethereal layer, dry it with anhydrous magnesium sulphate and evaporate the ether. Recrystallise the residual anihde, which is obtained in almost quantitative yield, from dilute alcohol or other suitable solvent. 

The aniline and sulphuric acid are cautiously mixed in a round flask (250 c.c.) and heated to 180—190° in an oil or metal bath for four to five hours until a sample dissolved in water remains clear on the addition of caustic soda in excess and no aniline separates. The product is poured into cold water, which precipitates the sulphanilic acid as a grey ciystalline mass.It is filtered, washed with a little cold water, recrystallised from hot water with the addition of a little animal charcoal, and dried in the air. Yield, 25 — 30 grams. 

Cool the reaction mixture to room temperature and add gradually a solution of 76 g. of sodium hydroxide in 126 ml. of water if the mixture boils during the addition of the alkali, cool again. The hydroxide of tin which is first precipitated should all dissolve and the solution should be strongly alkaline the aniline separates as an oil. Equip the flask for steam distillation as in Fig. II, 40, 1, and pass steam into the warm... 

A mixture of 25 gms. (1 mol.) of redistilled aniline and 30 gms. (excess) of glacial acetic acid is boiled under an air condenser, preferably in a flask with a condenser ground into the neck, until no aniline separates on treating a sample with a cold caustic soda solution (8 hours). The hot liquid is at once poured into 500 c.cs. of cold water, filtered, and washed with cold water. The crude acetanilide is boiled with a litre of water, a little alcohol being added until it all goes into solution. It is filtered through a hot water filter (see p. 11), and the solution allowed to crystallise. If the product is dark coloured, it is redissolved as before, boiled with 5 gms. of animal charcoal for hour, filtered, and allowed to crystallise. 

Phenylcarbamate, phenylurea and many amide herbicides which yield anilines on hydrolysis can be detected after TLC by spraying with fluorescamine [100]. The limits of detection of a number of anilines separated by TLC and detected with fluorescamine are given in Table 4.16. A number of pesticides which yield anilines on hydrolysis or degradation is listed in Table 4.28. The analysis of anilines by this technique is described in Section 4.2.1.2.3. 

Aniline does not give water-stable salts with weak acids like acetic acid. Some aromatic amines do give crystalline acetates with acetic acid, but these are decomposed by water with separation of the free base. This property is utilized industrially in the isolation of m-xylidine from a mixture containing its isomers. Hence, free aniline separates out of an aqueous solution of an aniline salt with a mineral acid if the mineral acid anion is replaced by the acetate ion, for example, by the addition of sodium acetate in sufficient concentration. 

Figure 4.86 Gradient elution of anilines. Separator column lonPac CS12A column temperature 40 °C eluent H2SOVMeCN gradient ...

Fig. 4-76. Gradient elution of anilines. Separator column lonPac CS12A column temperature 40 C eluant H2SO4-acetonitrile gradient 20 mmol/L H2S04-acetonitrile (95 5 v/v) to 20 mmol/L H2SO4-acetonitrile (75 25 v/v) in 10 min, then to 20 mmol/L H2S04-acetonitrile (40 60 v/v) in 17 min flow rate 1 mL/min detection UV...

The compositions of the two liquid phases in equilibrium are obtained by a horizontal tie line, as shown below. In this example, a mixture of 15% mcp, 60% hexane, and 25% aniline separates into two liquid phases one phase is 15% mcp, 75% hexane, and 10% aniline and the other phase is 15% mcp, 10% hexane, and 75% aniline. 

The nitrobenzene is placed in a reducer, which is a vertical cylindrical vessel provided with cover, steam jacket, and agitator. The iron turnings, or powder, and a small amount of hydrochloric acid are added in small portions. A brisk reaction is maintained by means of steam circulated in the jacket of the reducer or blown directly into the charge. A condenser returns to the reducer any vapors that escape. After the nitrobenzene is completely converted to aniline, a strong current of live steam is passed into the charge a mixture of steam and aniline vapors passes to the condenser and is collected in storage tanks. The bulk of the aniline separates as a lower layer and is drawn off the water over... 

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