Question

Which of the following is not true for $S_N1$ reaction ?

• A. Favoured by polar solvents
• B. $3^\circ$ - alkyl halides generally react through $S_N1$ reaction
• C. The rate of the reaction does not depend upon the molar concentration of the nucleophile
• D. $1^\circ$ - alkyl halides generally react through $S_N1$ reaction.

Answer 1

Answer: (D)

In $S _{ N } 1$ reactions, rate of the reaction depends upon the concentration of the substrate only. It does not depend upon the concentration of the nucleophile.

In this type of reaction, covalent nucleophile reacts/attacks on substrate. $3^{\circ}$ alkyl halide generally react by this mechanism, whereas $1^{\circ}$ alkyl halide generally follow $S _{ N } 2$ reactions. $S _{ N } 1$ reactions are favoured by polar solvents.