Laboratory method of Preparation of Aniline - QS Study
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Laboratory method of preparation of aniline

Principle: in laboratory, when nitrobenzene is heated with tin and HCl, aniline is formed. The reaction of tin (Sn) and conc HCl produce nascent hydrogen and SnCl2 or SnCl4, the nascent hydrogen reduces – NO2 group to – NH2 group.

Method of preparation:

(i) Aniline formation: A mixture of nitrobenzene, tin and hydrochloric acid is taken in a flask attached with reflux condenser and heated at 700C for half an hour, this produce aniline.

(ii) Separation of aniline: The produced aniline further reacts with HCl forming anilinium hydrochloride salt. When an alkali solution is added to this salt, aniline is separated and remains floating forming a layer of dark brown oil.

(iii) Extraction of aniline: When the oil undergoes steam distillation aniline is distilled along with water in the receiver flask. When the distilled liquid is saturated by common salt aniline is separated in the form of oil. This oil is then separated by a separating funnel.

 (iv) Purification: Aniline so found, then dissolved in ether and dried by solid caustic potash. When it is refluxed at 1840C we get pure Aniline.