Organic Chemistry Multiple Choice Questions on “Reactions of Phenols”.
1. Phenolphthalein is obtained by heating phenol with conc. H2SO4 and which of the following reactant?
a) Benzyl alcohol
b) Benzene
c) Benzoic acid
d) Phthalic anhydride
Answer: d
Clarification: Phenolphthalein is obtained by heating phenol with conc. H2SO4 and phthalic anhydride, as shown in the given reaction.
2. Salicylaldehyde can be prepared from which of the following reactants?
a) Phenol and chloroform
b) Phenol, chloroform and sodium hydroxide
c) Phenol, carbon tetrachloride and NaOH
d) Phenol, carbon tetrachloride
Answer: b
Clarification: Salicylaldehyde is prepared from phenol and chloroform by heating with sodium hydroxide or potassium hydroxide in a Reimer–Tiemann reaction.
3. When phenol is treated with excess of bromine water, it gives which of the following product?
a) m-bromophenol
b) o-and p-bromophenol
c) 2,4-dibromophenol
d) 2,4,6-tribromophenol
Answer: d
Clarification: In phenol, the hydroxyl group serves to greatly activate the benzene ring, significantly increasing its reactivity, hence susceptibility to substitution. The reaction occurs at room temp and even goes to maximum substitution of the 3 possible locations (2,4,6). result is 2,4,6-tribromophenol which is a white ppt.
4. Phenol reacts with bromine in carbon disulphate at low temperature to give which of the following product?
a) m-bromophenol
b) o-and p-bromophenol
c) p-bromophenol
d) 2,4,6-tribromophenol
Answer: b
Clarification: Phenol reacts with bromine in carbon disulphate at low temperature to give o-and p-bromophenol.