A compound (X) containing C, H and O does not react with sodium. It also does not reduce Tollens’ reagent. On heating with an excess of hydroiodic acid (HI), (X) gives only one organic product (Y). On hydrolysis, (Y) gives a new compound (Z), which can be converted back into (Y) by reaction with red phosphorus and iodine. On oxidation with potassium permanganate, (Z) gives a monocarboxylic acid whose molar mass is 60 g mol−1.
What is the compound (Y)?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Ethyl iodide
An ether is cleaved by an excess of a hydrogen halide; a dialkyl ether gives two alkyl halide molecules. If both alkyl groups are the same, the two molecules are the same compound.
Compound (X): no reaction with sodium means no –OH group; no reduction of Tollens’ reagent means no –CHO group. A C, H, O compound split by HI is an ether.
Compound (Z): it is oxidised by KMnO4 to a monocarboxylic acid of molar mass 60 g mol−1, \( \ce{CH3COOH} \) (14n + 46 = 60, n = 1), so (Z) is ethanol.
Compound (Y): it is hydrolysed to ethanol and made back from ethanol with red phosphorus and iodine, so (Y) is ethyl iodide, \( \ce{C2H5I} \).
Only one product: (X) is the symmetrical ether ethoxyethane, \( \ce{C2H5-O-C2H5} \).
\( \displaystyle \ce{C2H5-O-C2H5 + 2HI} \xrightarrow{\text{heat}} \ce{2C2H5I + H2O} \)
\( \displaystyle \ce{C2H5I + KOH(aq) -> C2H5OH + KI} \)
\( \displaystyle \ce{3C2H5OH + PI3 -> 3C2H5I + H3PO3} \) (\( \ce{PI3} \) formed from red phosphorus and iodine)
A mixture of ethyl iodide and methyl iodide would come from the unsymmetrical ether ethyl methyl ether, which does not fit “only one organic product”.
NCERT (2026-27 edition):
7.6.3 Chemical Reactions – “Ethers are the least reactive of the functional groups. The cleavage of C-O bond in ethers takes place under drastic conditions with excess of hydrogen halides. The reaction of dialkyl ether gives two alkyl halide molecules.”