Which among the following compounds will undergo fastest \(S_N2\) reaction?
The Correct Option is C
Approach Solution - 1
To determine which compound undergoes the fastest \(S_N2\) reaction, we must consider the factors that influence \(S_N2\) reactions. The \(S_N2\) mechanism involves a one-step process where the nucleophile attacks the electrophilic carbon from the opposite side, causing the leaving group to leave simultaneously. Some key factors affecting \(S_N2\) reactions include:
- Substrate Structure: \(S_N2\) reactions favor less sterically hindered substrates. Primary halides react faster than secondary, which react faster than tertiary halides.
- Nucleophile Strength: A strong nucleophile will enhance the rate of \(S_N2\) reactions, but this factor is constant across similar groups in different substrates.
- Leaving Group Ability: A good leaving group increases the \(S_N2\) reaction rate. Typically, weak bases make better leaving groups.
- Solvent Effects: Polar aprotic solvents favor \(S_N2\) reactions by solvating cations well, thereby freeing anions to attack the substrate.
Let us analyze each of the given options based on steric hindrance:
This compound is a tertiary alkyl halide. Tertiary halides are highly hindered and react very slowly, if at all, via an \(S_N2\) mechanism.
This compound is a secondary alkyl halide. Although it can undergo \(S_N2\) reactions, it is more hindered than primary halides.
This compound is a primary alkyl halide. Primary halides are less hindered and usually the best candidates for \(S_N2\) reactions.
This compound is a primary halide too, but given the branching nearby, it could be slightly more hindered compared to the simplest primary halide.
Thus, the compound shown in the following image:
is the correct answer as it is a primary halide with minimal hindrance, allowing the fastest \(S_N2\) reaction.
Approach Solution -2
The \(S_N2\) reaction rate depends on steric hindrance. Primary alkyl halides react faster than secondary or tertiary halides:
Rate of \(S_N2\) : methyl halide > primary > secondary > tertiary.
Among the given options:
Top Questions on Organic Chemistry
Consider the following two reactions A and B:
The numerical value of [molar mass of $x$ + molar mass of $y$] is ___.
- JEE Main - 2026
- Chemistry
- Organic Chemistry
- Given below are two statements:
Statement I: $CH_3)_3C^+$ is more stable than $CH_3CH_2^+$ as nine hyperconjugation interactions are possible in $(CH_3)_3C^+$.
Statement II: $CH_3^+$ is less stable than $(CH_3)_3C^+$ as only three hyperconjugation interactions are possible in $CH_3^+$.
In the light of the above statements, choose the correct answer...- JEE Main - 2026
- Chemistry
- Organic Chemistry
Which one of the following graphs accurately represents the plot of partial pressure of CS₂ vs its mole fraction in a mixture of acetone and CS₂ at constant temperature?
- JEE Main - 2026
- Chemistry
- Organic Chemistry
- \(0.53\ \text{g}\) of an organic compound \(X\) when heated with excess concentrated nitric acid and then with silver nitrate gave \(0.75\ \text{g}\) of silver bromide precipitate. \(1.0\ \text{g}\) of \(X\) gave \(1.32\ \text{g}\) of \(\mathrm{CO_2}\) on combustion. Find the percentage of hydrogen in compound \(X\). (Nearest integer) [Given: Atomic masses (g mol\(^{-1}\)): H = 1, C = 12, Br = 80, Ag = 108, O = 16]
- JEE Main - 2026
- Chemistry
- Organic Chemistry
Consider the following reaction sequence:
Given: Compound (x) has percentage composition \(76.6%\ \text{C}\), \(6.38%\ \text{H}\) and vapour density \(=47\). Compound (y) develops a characteristic colour with neutral \(\mathrm{FeCl_3}\) solution. Identify the {INCORRECT statement.}- JEE Main - 2026
- Chemistry
- Organic Chemistry
Questions Asked in JEE Main exam
The equivalent resistance between the points \(A\) and \(B\) in the given circuit is \[ \frac{x}{5}\,\Omega. \] Find the value of \(x\).
- JEE Main - 2026
- Current electricity
Method used for separation of mixture of products (B and C) obtained in the following reaction is:
- JEE Main - 2026
- p -Block Elements
- Consider light travelling from a medium A to medium B separated by a plane interface. If the light undergoes total internal reflection during its travel from medium A to B and the speed of light in media A and B are \(2.4 \times 10^8\) m/s and \(2.7 \times 10^8\) m/s, respectively, then the value of critical angle is :
- JEE Main - 2026
- Newtons Laws of Motion
In the following \(p\text{–}V\) diagram, the equation of state along the curved path is given by \[ (V-2)^2 = 4ap, \] where \(a\) is a constant. The total work done in the closed path is:
- JEE Main - 2026
- Thermodynamics
Let \( ABC \) be a triangle. Consider four points \( p_1, p_2, p_3, p_4 \) on the side \( AB \), five points \( p_5, p_6, p_7, p_8, p_9 \) on the side \( BC \), and four points \( p_{10}, p_{11}, p_{12}, p_{13} \) on the side \( AC \). None of these points is a vertex of the triangle \( ABC \). Then the total number of pentagons that can be formed by taking all the vertices from the points \( p_1, p_2, \ldots, p_{13} \) is ___________.
- JEE Main - 2026
- Coordinate Geometry