For the following reaction sequence, choose the correct option [figure]
- Both P and Q are carbonyl compounds
- If P is the sodium salt of a carboxylic acid, Q is a primary alcohol
- P and Q are aromatic compounds
- If P gives a carboxylic acid on acidification, Q gives a poisonous gas on exposure to air and light
Answer
(4) If P gives a carboxylic acid on acidification, Q gives a poisonous gas on exposure to air and light
Solution
1. Benzene undergoes Friedel-Crafts acylation with CH3COCl / AlCl3 to give acetophenone (C6H5COCH3).
2. Haloform reaction of acetophenone with NaOCl gives sodium benzoate (P, C6H5COONa) and chloroform (Q, CHCl3).
3. On acidification, P yields benzoic acid (a carboxylic acid).
4. Chloroform (Q) is slowly oxidised by air in the presence of light to form phosgene (COCl2), an extremely poisonous gas:
2CHCl3 + O2 h 2COCl2 + 2HCl. Answer: (4)