Starting with 137 mg of 4-nitrotoluene (C₇H₉NO₂, MW = 137).
Step 1: Reduction with Sn/HCl converts NO₂ to NH₂, producing 4-aminotoluene (A).
Step 2: Acetylation with (CH₃CO)₂O produces the acetamide intermediate, then bromination with Br₂/AcOH adds bromine to the para position (ortho-para directing due to acetamide group), yielding 4-bromo-N-(4-methylphenyl)acetamide (B) with molecular formula C₉H₁₀BrNO and MW = 228 g/mol.
Moles of starting material = 137 mg ÷ 137 g/mol = 1 mmol.
Assuming complete reaction, moles of B produced = 1 mmol.
Mass of B = 1 mmol × 228 mg/mmol = 228 mg.
