Question

Directions: Each question contains Statement- 1 and Statement-2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct. (a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1 (b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement- 1 (c) Statement- 1 is True, Statement- 2 is False (d) Statement- 1 is False, Statement- 2 is True Statement 1 \(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{O}-\mathrm{CH}_{2} \mathrm{Br}\) undergoes hydrolysis faster than \(\mathrm{CH}_{3}-\mathrm{O}-\mathrm{CH}_{2}-\mathrm{CH}_{2} \mathrm{Br}\) and Statement 2 The carbocation formed by ionization of \(\mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{OCH}_{2} \mathrm{Br}\) is stabilized by resonance.

Short answer

a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1. b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement- 1. c) Statement- 1 is True, Statement- 2 is False. d) Statement- 1 is False, Statement- 2 is True. Answer: a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1.

Step-by-step solution

Examine the Hydrolysis Reaction

The hydrolysis reaction typically involves breaking down a compound (in this case an organic compound) in the presence of water. We need to compare the reaction rates of CH3-CH2-O-CH2Br and CH3-O-CH2-CH2Br in the hydrolysis reaction.

Compare Reaction Rates

To compare the reaction rates, we must consider the following factors: - Stability of the intermediates formed in the reactions - Electronic effects that can stabilize the intermediates Comparing CH3-CH2-O-CH2Br and CH3-O-CH2-CH2Br, we can see that the difference between these two compounds is the position of the oxygen atom in the organic chain.

Analyze the Carbocation Formation of Statement 2

Let's focus on the carbocation formation of CH3-CH2-OCH2Br and study its stability. When CH3-CH2-OCH2Br undergoes hydrolysis and loses a bromide ion, it forms a carbocation: \((CH_3-CH_2-O-CH_2)^+\). This carbocation can be stabilized through resonance as the positive charge can be delocalized between the oxygen and carbon atoms, which increases the stability of the ions and leads to a faster hydrolysis reaction.

Determine the Correctness and Relation of the Statements

Based on our analysis, we can determine the following: - Statement 1 is true as CH3-CH2-O-CH2Br undergoes hydrolysis at a faster rate due to the factors we analyzed. - Statement 2 is also true as the carbocation formed by ionization of CH3-CH2-OCH2Br is stabilized by resonance. Now, we must determine how these statements are related. Since the stability of the carbocation through resonance explains why CH3-CH2-O-CH2Br undergoes hydrolysis faster than CH3-O-CH2-CH2Br, we can conclude that Statement 2 is a correct explanation for Statement 1. Therefore, the correct choice is (a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1.

Key concepts

Hydrolysis Reaction

A hydrolysis reaction is a crucial concept in organic chemistry where a compound is broken down with the addition of water. In this specific situation, we are examining two organic compounds: \( \mathrm{CH}_3-\mathrm{CH}_2-\mathrm{O}-\mathrm{CH}_2\mathrm{Br} \) and \( \mathrm{CH}_3-\mathrm{O}-\mathrm{CH}_2-\mathrm{CH}_2\mathrm{Br} \). During hydrolysis, these compounds react with water to form alcohols and hydrogen bromide. The rate of hydrolysis depends significantly on the stability of intermediates formed during the reaction.

To understand why one compound hydrolyzes faster than the other, we need to study the stability of the intermediate carbocations formed. Enhanced stability usually leads to a faster reaction.

A hydrolysis reaction not only transforms the structure of the molecule but also involves breaking down bond connections. Understanding how intermediates behave during such a reaction is vital for grasping the underlying mechanism.

Carbocation Stability

Carbocations are positively charged ions which play a key role in organic reaction mechanisms. In our exercise, the compound \( \mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OCH}_2\mathrm{Br} \) forms a carbocation, \( (\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OCH}_2)^+ \). The stability of this carbocation is the determining factor for the speed of hydrolysis.

The stability of a carbocation is influenced by several factors:

• Hyperconjugation: Alkyl groups attached to the positively charged carbon can donate electron density via sigma bonds, stabilizing the carbocation.
• Resonance: Delocalization of the positive charge over adjacent atoms enhances the stability.

The more stable the carbocation, the more readily the reaction will proceed. In the case of \( \mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OCH}_2\mathrm{Br} \), resonance is a major factor stabilizing the carbocation, leading to a faster hydrolysis.

Resonance Effect

The resonance effect involves the delocalization of electrons within a molecule, which significantly impacts stability. This effect is prominent in carbocations where electron pair sharing occurs between adjacent atoms.

For the carbocation \( (\mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OCH}_2)^+ \), resonance allows the positive charge to be distributed over the oxygen and carbon atoms. Oxygen, with its high electronegativity, can share its lone pair electrons, thereby delocalizing the charge and stabilizing the carbocation.

The increased stability from resonance improves reaction rates. It explains why \( \mathrm{CH}_3-\mathrm{CH}_2-\mathrm{OCH}_2\mathrm{Br} \) undergoes hydrolysis more rapidly compared to its isomer \( \mathrm{CH}_3-\mathrm{O}-\mathrm{CH}_2-\mathrm{CH}_2\mathrm{Br} \). In this case, the resonance structure contributes to a more efficient and faster chemical transformation.

Reaction Mechanisms

Reaction mechanisms provide a detailed step-by-step description of how a reaction proceeds. Understanding this sequential pathway aids in predicting the behavior of organic reactions.

In our hydrolysis scenario, the mechanism involves the formation and stabilization of a carbocation intermediate. Here is how it typically unfolds:

• An initial ionization step where the bromide leaves, forming a carbocation.
• Stabilization of the carbocation through resonance and hyperconjugation.
• Nucleophilic attack by water to complete the hydrolysis, forming an alcohol and HBr.

Each step is influenced by the stability of the intermediates, which we understand through resonance effects and carbocation stability. Observing these mechanisms provides insight into why certain structures react faster, underscoring the importance of understanding intermediate stability in comprehending organic reactions.