Read the following passage and answer questions.
Nucleophiles attack at that part of the substrate molecule which is electron deficient. The reaction in which a nucleophile replaces already existing nucleophile in a molecule is called nucleophilic substitution reaction. Haloalkanes are substrates in these reactions. In this type of reaction, a nucleophile reacts with haloalkane (the substrate) having a partial positive charge on the carbon atom bonded to halogen. A substitution reaction takes place and halogen atom, called leaving group departs as halide ion. Since the substitution reaction is initiated by a nucleophile, it is called nucleophilic substitution reaction.
When NaOH reacts with R-X, what is the major product ?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Alcohol
In a nucleophilic substitution, the nucleophile takes the place of the halogen on the carbon atom. Aqueous NaOH (or KOH) provides the hydroxide ion, \( \ce{OH-} \), as the nucleophile, so the halogen is replaced by –OH and an alcohol is formed:
\( \displaystyle \ce{R-X + NaOH(aq) -> R-OH + NaX} \)
Why the other options are incorrect
Option (2) Ether — Incorrect. An ether is formed when the nucleophile is an alkoxide ion (\( \ce{R'O-} \), from \( \ce{NaOR'} \)), as in the Williamson synthesis.
Option (3) Ester — Incorrect. An ester needs a carboxylate nucleophile, \( \ce{R'COO-} \) (from \( \ce{R'COOAg} \)).
Option (4) Acid — Incorrect. Substitution by \( \ce{OH-} \) puts an –OH on the carbon; it does not create a –COOH group.
NCERT (2026-27 edition):
Reactions of Haloalkanes – Table 6.4: Nucleophilic Substitution of Alkyl Halides (R–X)
| Reagent | Substitution product R–Nu | Class of main product |
|---|---|---|
| NaOH (KOH) | ROH | Alcohol |
| H2O | ROH | Alcohol |
| NaOR′ | ROR′ | Ether |
| NaI | R—I | Alkyl iodide |
| NH3 | RNH2 | Primary amine |
| R′NH2 | RNHR′ | Sec. amine |
| R′R″NH | RNR′R″ | Tert. amine |
| KCN | RCN | Nitrile (cyanide) |
| AgCN | RNC | Isonitrile (isocyanide) |
| KNO2 | R—O—N=O | Alkyl nitrite |
| AgNO2 | R—NO2 | Nitroalkane |
| R′COOAg | R′COOR | Ester |
| LiAlH4 | RH | Hydrocarbon |
| R′– M+ | RR′ | Alkane |