Prepare a pure sample of P-nitro acetanilide from acetanilide

 Prepare a pure sample of P-nitro acetanilide from acetanilide

Theory:

P.Nitro-acetanilide can be prepared by nitration of of Acetanilide with a mixture of conc HNO3 , and conc. H2SO4 . The reaction mixture is decomposed with crushed ice. The solid product is separated by filtration through a buchner funnel and crystallised from rectified spirit.

Requirements:

(a) Apparatus:

250 ml. round bottomed flask, beaker, measuring cylinder, balance, weight box, air condenser, iron stand, etc. 

(b) Chemicals:

(i) Acetanilide = 8.0 g

(ii) Glacial acetic acid = 10.0ml

(iii) Conc.HNO3= 4.0ml

(iv) Conc.H2SO4 = 20.0ml

(v) Crushed ice = ........

Chemical Equations:

Procedure:

• Take 8.0 g of acetanilide in a 250 ml, round bottom flask and add 8.0 ml of glacial acetic acid and 10.0 ml of concentration. H2SO4. Install the air condenser into the round bottom flask.
• Mix 4.0ml. concentration, HNO3, in 4.0 ml. the H2SO4 cone in the tube boils and cools the mixture. Add the nitrated mixture solution to the acetanilide solution in the round bottom flask dropwise while stirring keeping the temperature below 10℃. Cool under tap water if the temperature tends to get out of control. 
• After adding the acid mixture, let sit for about an hour. 
• Decompose the mixture and the reaction by adding slowly with a string to 200 ml of ice-cold water. The P-nitro acetanilide precipitate will separate. 
• Separate the solid product by filtration through a Buchner funnel using a suction pump. Wash the raw product with water.
• Dry the coarse product at 100 °C in an electric oven, Crystallization of the crude product of the refined spirits, when the pale yellow crystals of P-Nitro acetanilide separate. 
• Separate the crystals from the mother liquor by filtering through a Buchner funnel under suction. 
• Dry the crystals in a desiccator. Record the weight of the product formed and determine the melting point.

Result :

• Colour of crystals = pale yellow
• Yield = about 6.0 g
• Melting point= 214  ℃

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