back to directory
NEET CHEMISTRYHaloalkanes and HaloarenesMedium

Question

In SN2S_N2 substitution reaction of the type R-Br+ClDMFR-Cl+Br\text{R-Br} + \text{Cl}^- \xrightarrow{\text{DMF}} \text{R-Cl} + \text{Br}^-, which one of the following has the highest relative rate?

A

CH3-CH2-CH2Br\text{CH}_3\text{-CH}_2\text{-CH}_2\text{Br}

B

CH3-CH(CH3)-CH2Br\text{CH}_3\text{-CH(CH}_3\text{)-CH}_2\text{Br}

C

CH3-C(CH3)2-CH2Br\text{CH}_3\text{-C(CH}_3)_2\text{-CH}_2\text{Br}

D

CH3CH2Br\text{CH}_3\text{CH}_2\text{Br}

Step-by-Step Solution

The given reaction proceeds via an SN2S_N2 mechanism. The rate of an SN2S_N2 reaction is highly dependent on the steric hindrance (spatial arrangement) around the electrophilic carbon atom. As the steric bulk around the α\alpha-carbon increases, the approach of the incoming nucleophile (Cl\text{Cl}^-) is hindered, leading to a lower reaction rate. Among the given primary alkyl bromides, bromoethane (CH3CH2Br\text{CH}_3\text{CH}_2\text{Br}) has the least steric hindrance. Branching at the β\beta-carbon (as seen in the other options: propyl, isobutyl, and neopentyl bromides) increases steric resistance, making the approach of the nucleophile difficult. Thus, CH3CH2Br\text{CH}_3\text{CH}_2\text{Br} has the highest relative rate.

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from Haloalkanes and Haloarenes. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

CHEMISTRYHaloalkanes and Haloarenessubstitutionreactiontextrbrtextclxrightarrowtextdmf

More Haloalkanes and Haloarenes Questions

View all

In the given reaction the product P is:

A.[Image Missing]
B.[Image Missing]
C.4
D.[Image Missing]
MediumSolve

Given below is a reaction sequence: $\text{CH}_3\text{CH}_2\text{Cl} \xrightarrow{\text{NaCN}} X \xrightarrow{\text{H}_2/\text{Ni}} Y \xrightarrow{\text{Acetic Anhydride}} Z$ The product '$Z$' in the above reaction is:

A.$\text{CH}_3\text{CH}_2\text{CH}_2\text{NHCOCH}_3$
B.$\text{CH}_3\text{CH}_2\text{CH}_2\text{NH}_2$
C.$\text{CH}_3\text{CH}_2\text{CH}_2\text{CONHCH}_3$
D.$\text{CH}_3\text{CH}_2\text{CH}_2\text{CONHCOCH}_3$
MediumSolve

The $\text{-OH}$ group of an alcohol or the carboxylic acid can be replaced by $\text{-Cl}$ using:

A.Hypochlorous acid
B.Chlorine
C.Hydrochloric acid
D.Phosphorous pentachloride
EasySolve

The correct order of increasing C-X bond reactivity toward nucleophiles among the following is: I. [Missing] II. [Missing] III. $(\text{CH}_3)_3\text{C-X}$ IV. $(\text{CH}_3)_2\text{CH-X}$

A.I < II < IV < III
B.II < III < I < IV
C.IV < III < I < II
D.III < II < I < IV
MediumSolve

Which of the following methods is incorrect for the synthesis of alkenes?

A.Treatment of alkynes with Na in liquid $\text{NH}_3$
B.Heating alkyl halides with alcoholic $\text{KOH}$
C.Treating alkyl halides in aqueous $\text{KOH}$ solution
D.Treating vicinal dihalides with Zn metal
MediumSolve

The correct reaction among the following is:

A.Reaction 1
B.Reaction 2
C.Reaction 3
D.Reaction 4
MediumSolve

The major product formed in the dehydrohalogenation reaction of 2-bromopentane is pent-2-ene. This product formation is based on:

A.Hofmann Rule
B.Huckel's Rule
C.Saytzeff's Rule
D.Hund's Rule
EasySolve

A reaction among the following can generate isonitriles as a major product. (A) $\text{R-X} + \text{HCN} \rightarrow$ (B) $\text{R-X} + \text{AgCN} \rightarrow$ (C) $\text{R-X} + \text{KCN} \rightarrow$ (D) $\text{R-X} + \text{NaCN} \xrightarrow{\text{C}_2\text{H}_5\text{OH}/\text{H}_2\text{O}}$ Choose the most appropriate answer from the options given below:

A.(D) only
B.(C) and (D) only
C.(B) only
D.(A) and (B) only
MediumSolve

This neet chemistry practice question is part of the TopperSquare free question bank. TopperSquare offers 15,000+ chapter-wise NEET MCQs across Physics, Chemistry, and Biology with detailed step-by-step explanations, full mock tests, NEET PYQs (2010–2024), and an AI-powered performance analytics dashboard. browse all neet practice questions → · practice chemistry sets →