Which of the following statements are not correct?
A. Phenol is used to prepare analgesic drugs.
B. Solubility of phenol in water is more than that of chlorobenzene
C. Phenol is neutralized by sodium carbonate
D. Boiling point of o-nitrophenol is greater than that of p-nitrophenol
Choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → C and D only
Phenol is a very weak acid: it reacts with NaOH but not with carbonates or hydrogencarbonates. Its –OH group forms hydrogen bonds, with water and, in nitrophenols, either inside one molecule or between molecules.
(A) Phenol is used to prepare analgesic drugs. — True. Sodium phenoxide reacts with \( \ce{CO2} \) (Kolbe’s reaction) and gives salicylic acid after acidification. Acetylation of salicylic acid gives aspirin, an analgesic.
\( \ce{C6H5OH + NaOH -> C6H5ONa + H2O} \)
\( \ce{C6H5ONa} \xrightarrow[\text{(ii) }\ce{H+}]{\text{(i) }\ce{CO2},\ \text{4-7 atm, 400 K}} \underset{\text{salicylic acid}}{\ce{HOC6H4COOH}} \)
\( \ce{HOC6H4COOH + (CH3CO)2O} \xrightarrow{\ce{H+}} \underset{\text{aspirin}}{\ce{CH3COOC6H4COOH}} + \ce{CH3COOH} \)
(B) Solubility of phenol in water is more than that of chlorobenzene — True. The –OH group of phenol forms hydrogen bonds with water; chlorobenzene cannot, so it is almost insoluble.
(C) Phenol is neutralized by sodium carbonate — False. Phenol is a very weak acid (\( \mathrm{p}K_a \) about 10). Unlike a carboxylic acid, it does not decompose carbonates or hydrogencarbonates, so no \( \ce{CO2} \) is given off:
\( \ce{2RCOOH + Na2CO3 -> 2RCOONa + H2O + CO2 ^} \)
\( \ce{C6H5OH + Na2CO3 ->} \) no reaction(D) Boiling point of o-nitrophenol is greater than that of p-nitrophenol — False. o-Nitrophenol has intramolecular hydrogen bonding, so its molecules are not associated. p-Nitrophenol has intermolecular hydrogen bonding, which associates the molecules and gives it the higher boiling point.
NCERT (2026-27 edition):
Solubility – “Solubility of alcohols and phenols in water is due to their ability to form hydrogen bonds with water molecules as shown.”
Electrophilic Aromatic Substitution – “… The ortho and para isomers can be separated by steam distillation. o-Nitrophenol is steam volatile due to intramolecular hydrogen bonding while p-nitrophenol is less volatile due to intermolecular hydrogen bonding which causes the association of molecules.”
Esterification – “… The introduction of acetyl (\( \ce{CH3CO} \)) group in alcohols or phenols is known as acetylation. Acetylation of salicylic acid produces aspirin.” “Aspirin possesses analgesic, anti-inflammatory and antipyretic properties.”
Reactions with Metals and Alkalies – “The carboxylic acids like alcohols evolve hydrogen with electropositive metals and form salts with alkalies similar to phenols. However, unlike phenols they react with weaker bases such as carbonates and hydrogencarbonates to evolve carbon dioxide.”