Organic 2 Review Problem 267

Organic 2 Review Problem 267 - PREPARATIONS 251 then cool...

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PREPARATIONS 251 then cool in ice-water to complete the process. The toluene- />-sulphonyl-aniline, C 6 H 5 NHSO 2 C 6 H 4 CH 3 , when filtered and drained is obtained as colourless crystals, m.p. 102°: yield, 6 g. The aniline and the monomethylaniline can be obtained from their respective sulphonyl derivatives by hydrolysis with 70% sulphuric acid (preparation, p. 109), the mixture of the sulphonyl compound and the acid being gently boiled under reflux: to illustrate the separation of the three amines, however, this is not necessary. The chief disadvantage of Hinsberg's method is that partial hydrolysis of the two sulphonyl amines by the sodium hydroxide may occur during the steam-distillation: if, however, only a small excess of the hydroxide is used in the sulphonylation, this hydrolysis becomes negligible, particularly as the sul- phonyl amides are far less readily hydrolysed by alkalis than by acids. This point does not arise in the separation of a similar mixture of aliphatic amines,
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