Question

The reaction between napthalene and chromium trioxide in the presence of glacial acetic yields:

• A. Naphthalene-1.4-dione
• B. 4-Hydroxynaphthalen-1 (4H)-one
• C. Napthanelen-1.2-dione
• D. 1-Hydroxynaphthalen-2(1H)-one

Answer 1

The Correct Option is A

In the given reaction, naphthalene is treated with chromium trioxide (\text{CrO}_3) in the presence of glacial acetic acid. This is an oxidative reaction where naphthalene is oxidized by chromium trioxide, which acts as an oxidizing agent. Let's analyze the reaction step-by-step:

1. Chromium trioxide is a strong oxidizing agent commonly used for converting aromatic compounds into quinones.
2. Naphthalene is a polycyclic aromatic hydrocarbon that can undergo oxidation when exposed to strong oxidizing agents.
3. In the presence of glacial acetic acid, an organic solvent, chromium trioxide facilitates the oxidation of naphthalene into naphthoquinones.
4. The specific oxidation product formed most commonly when naphthalene reacts with chromium trioxide is naphthalene-1,4-dione, also known as 1,4-naphthoquinone.

Let's understand why this specific quinone is formed:

1. Naphthalene-1,4-dione is formed due to the preferential oxidation at the 1 and 4 positions in the naphthalene ring, which is stabilized by resonance structures.
2. The oxidation involves the removal of two hydrogen atoms from naphthalene, resulting in the formation of two carbonyl groups (C=O) at these positions.
3. Naphthalene-1,4-dione is a stable compound due to the conjugated system of double bonds and carbonyl groups in its structure.

Among the given options, Naphthalene-1.4-dione accurately describes the product of the reaction between naphthalene and chromium trioxide in glacial acetic acid:

• Naphthalene-1.4-dione: The correct option as explained above.
• 4-Hydroxynaphthalen-1(4H)-one: Incorrect, as it suggests a hydroxylation rather than oxidation to a quinone.
• Napthanelen-1.2-dione: Incorrect, as it implies oxidation at 1,2-positions which is less favorable.
• 1-Hydroxynaphthalen-2(1H)-one: Incorrect, as it represents a hydroxylation rather than oxidation.

Therefore, the correct answer is Naphthalene-1.4-dione.