JEE Challenger
More from Amines

Calculate Mass of Final Product in Multi Step Acetophenone Reaction

In the given reaction sequence, determine the total mass of D\mathbf{D} (in grams) produced starting with 10 moles10\text{ moles} of acetophenone.

(Given atomic weights in g mol−1\text{g mol}^{-1}: H=1\text{H} = 1, C=12\text{C} = 12, N=14\text{N} = 14, O=16\text{O} = 16, Br=80\text{Br} = 80. The yield (%) corresponding to the product in each step is indicated in parentheses)

Question Diagram 1
Official Numerical Answer495

Step-by-Step Solution

To find the total mass of the final product D\mathbf{D} produced, we need to trace the step-by-step chemical transformations from acetophenone, keeping track of the yield at each step and the molar mass of the resulting compounds.


Step 1: Conversion of Acetophenone to Compound A

Acetophenone (C6H5COCH3\text{C}_6\text{H}_5\text{COCH}_3) undergoes a haloform reaction with sodium hypobromite (NaOBr\text{NaOBr}), followed by acidic hydrolysis (H3O+\text{H}_3\text{O}^+), to yield benzoic acid (C6H5COOH\text{C}_6\text{H}_5\text{COOH}).

  • Compound A: Benzoic acid (C6H5COOH\text{C}_6\text{H}_5\text{COOH})
  • Initial moles of acetophenone: 10 moles10\text{ moles}
  • Yield: 60%60\%

Moles of A=10 moles×60100=6 moles\text{Moles of } \mathbf{A} = 10\text{ moles} \times \frac{60}{100} = 6\text{ moles}


Step 2: Conversion of Compound A to Compound B

Benzoic acid (A\mathbf{A}) reacts with ammonia (NH3\text{NH}_3) upon heating (Δ\Delta) to undergo amidation, forming benzamide (C6H5CONH2\text{C}_6\text{H}_5\text{CONH}_2).

  • Compound B: Benzamide (C6H5CONH2\text{C}_6\text{H}_5\text{CONH}_2)
  • Yield: 50%50\%

Moles of B=6 moles×50100=3 moles\text{Moles of } \mathbf{B} = 6\text{ moles} \times \frac{50}{100} = 3\text{ moles}


Step 3: Conversion of Compound B to Compound C

Benzamide (B\mathbf{B}) undergoes Hofmann bromamide degradation upon treatment with Br2/KOH\text{Br}_2 / \text{KOH} to give aniline (C6H5NH2\text{C}_6\text{H}_5\text{NH}_2).

  • Compound C: Aniline (C6H5NH2\text{C}_6\text{H}_5\text{NH}_2)
  • Yield: 50%50\%

Moles of C=3 moles×50100=1.5 moles\text{Moles of } \mathbf{C} = 3\text{ moles} \times \frac{50}{100} = 1.5\text{ moles}


Step 4: Conversion of Compound C to Compound D

Aniline (C\mathbf{C}) undergoes electrophilic aromatic substitution with 3 equivalents3\text{ equivalents} of bromine (Br2\text{Br}_2) in acetic acid (AcOH\text{AcOH}) to form 2,4,6-tribromoaniline (C6H4Br3N\text{C}_6\text{H}_4\text{Br}_3\text{N}).

  • Compound D: 2,4,6-tribromoaniline (C6H4Br3N\text{C}_6\text{H}_4\text{Br}_3\text{N})
  • Yield: 100%100\%

Moles of D=1.5 moles×100100=1.5 moles\text{Moles of } \mathbf{D} = 1.5\text{ moles} \times \frac{100}{100} = 1.5\text{ moles}


Calculation of Molar Mass of Compound D

The molecular formula of 2,4,6-tribromoaniline is C6H4Br3N\text{C}_6\text{H}_4\text{Br}_3\text{N}.

Using the given atomic weights (H=1\text{H} = 1, C=12\text{C} = 12, N=14\text{N} = 14, Br=80\text{Br} = 80):

Molar Mass of D=(6×12)+(4×1)+(3×80)+(1×14)\text{Molar Mass of } \mathbf{D} = (6 \times 12) + (4 \times 1) + (3 \times 80) + (1 \times 14) Molar Mass of D=72+4+240+14=330 g mol−1\text{Molar Mass of } \mathbf{D} = 72 + 4 + 240 + 14 = 330\text{ g mol}^{-1}


Calculation of Mass of Compound D

Mass of D=Moles of D×Molar Mass of D\text{Mass of } \mathbf{D} = \text{Moles of } \mathbf{D} \times \text{Molar Mass of } \mathbf{D} Mass of D=1.5 moles×330 g mol−1=495 g\text{Mass of } \mathbf{D} = 1.5\text{ moles} \times 330\text{ g mol}^{-1} = 495\text{ g}

Final Answer: The total mass of product D\mathbf{D} formed is 495495 (in grams).