Question

The ratio of number of oxygen atoms to bromine atoms in the product $Q$ is ___ $\times 10^{-1}$.

Answer 1

Correct Answer: 15

The initial compound with \( \text{OC}_2\text{H}_5 \) undergoes nitration to introduce a \( \text{NO}_2 \) group, yielding intermediate \( P \).

\[ \text{OC}_2\text{H}_5 \xrightarrow{\text{HNO}_3, \text{H}_2\text{SO}_4} \text{OC}_2\text{H}_5\text{NO}_2 \]

Bromination of \( P \) in the presence of Fe introduces two bromine atoms on the aromatic ring, resulting in product \( Q \).

\[ \text{OC}_2\text{H}_5\text{NO}_2 \xrightarrow{\text{2 Br}_2, \text{Fe}} \text{Br-OC}_2\text{H}_5\text{NO}_2\text{Br} \]

Count the number of oxygen and bromine atoms in product \( Q \):

• Oxygen atoms: 3 (one from \( \text{OC}_2\text{H}_5 \) and two from \( \text{NO}_2 \))
• Bromine atoms: 2

The ratio of oxygen to bromine atoms in \( Q \) is:

\[ \frac{3}{2} \times 10^{-1} = 15 \times 10^{-1} \]

Answer: 15