Aim: Preparation of m-nitroaniline from nitrobenzene

Requirements:

  • Nitro Benzene
  • Fuming Nitric acid
  • Sulfuric acid
  • Sodium Sulphide
  • Sodium Hydrogen Carbonate, Methanol

Procedure:

Step 1 Preparation of m- dinitrobenzene from nitrobenzene

Take 6.0 mL of fuming nitric acid in a 100 mL round bottomed flask and add carefully with shaking 12.0 mL con. Sulfuric acid and 6.0 mL Nitro benzene. After adding of nitro benzene heat this mixture with frequent shaking on a boiling water bath for 15 minutes. Allow the mixture to cool some times and pour it cautiously with vigorous stirring in to a about 250 mL cold water the dinitrobenzene solidities filtrate the precipitation wash with cold water and allow to drain as completely as possible. Recrystallized from alcohol and water M.P. of yield = 90 °C.

Step 2 Preparation of m-nitroaniline from m- dinitrobenzene

Dissolve 13.43 g. of crystallized sodium sulphide (N2S.9H2O) in 37.31 mL of water and add 4.47 mL NaHCO3 in small portion with constant stirring when all bicarbonate has dissolved completely add 37.31 methanol with stirring filter of the precipitation sodium carbonate wash the precipitate with three times 5 ml portion of methanol these contain about 1.08g of NaSH in solution and must be used forth with for reduction.

Dissolve 5.0 g. dinitrobenzene (DNB) in 37 mL of hot methanol in a 250 ml round bottom flask and with shaking the previously prepared methanolic solution of NaSH attach reflux condenser to the flask and boil the mixture gently for 20 min. and apply a distillation method distillation of most of the methanol from a water bath pour the liquid residue with stirring in to about from 200 mL of cold water collect a yellow crystals of m-nitro aniline wash with water and recrystallized by a methanol the yield of bright yellow needles.

Results:

Step 1

  • Theoretical Yield: ______________g.
  • Practical Yield: ________________g.
  • % Yield of the product: _____________%.
  • M.P of m- dinitrobenzene: ___________°C

Step 2

  • Theoretical Yield: ______________g.
  • Practical Yield: ________________g.
  • % Yield of the product: _____________%.
  • M.P of m-Nitroaniline: ___________°C

Chemical Reaction:

Mechanism:

Calculation:

Step 1

  • Theoretical Yield

Nitrobenzene: C6H5NO2 (123.0 g.) Density = 1.2 g/mL m-dinitrobenzene: C6H4N2O4 (168.0 g.)

From Chemical Reaction

123.0 g. Nitrobenzene                                  =                      168.0 g. m-dinitrobenzene

∴ 6.0 g. Nitrobenzene                                  =                      (?) g m-dinitrobenzene

                        = \frac{6.0 \times 168.0}{123.0}

                        = 8.2 g.

  • Practical Yield:

Actual weight of the dried product = ________________g.

  • % of Yield =\frac{\text { Practical Yield } \times 100}{\text { Theoretical Yield }}

                             = _______________%

Step 2

  • Theoretical Yield

m-dinitrobenzene: C6H4N2O4 (168.0 g.) m-nitroaniline: C6H6N2O2 (138.0 g.)

From Chemical Reaction

168.0 g. m-nitrobenzene                              =                      138.0 g. m-nitroaniline

∴ 5.0 g. m-nitrobenzene                               =                      (?) g m-nitroaniline

                        = \frac{5.0 \times 138.0}{168.0}

                        = 4.10 g.

  • Practical Yield:

Actual weight of the dried product = ________________g.

  • % of Yield =\frac{\text { Practical Yield } \times 100}{\text { Theoretical Yield }}

                             = _______________%