Problem 33 - A Complete Resource Book in Chemistry for JEE Main

Question

The ether that undergoes electrophilic substitution reaction is (a) \(\mathrm{CH}_{3} \mathrm{OCH}_{3}\) (b) \(\mathrm{CH}_{3} \mathrm{OC}_{2} \mathrm{H}_{5}\) (c) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OC}_{2} \mathrm{H}_{5}\) (d) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OCH}_{3}\)

Step-by-Step Solution

Answer

Option (d) \( \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OCH}_{3} \) is the ether that undergoes electrophilic substitution.

Step 1: Understanding Electrophilic Substitution

Electrophilic substitution reactions typically involve organic compounds that contain aromatic rings. An electrophile replaces an atom, typically hydrogen, within the aromatic ring. Reactivity in electrophilic substitution is majorly observed in benzene rings or compounds containing benzene rings.

Step 2: Identify Aromatic Compounds in Options

Look at each option to determine which compound contains an aromatic benzene ring. - Option (a) \( \mathrm{CH}_{3} \mathrm{OCH}_{3} \) contains no benzene ring.- Option (b) \( \mathrm{CH}_{3} \mathrm{OC}_{2} \mathrm{H}_{5} \) contains no benzene ring.- Option (c) \( \mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OC}_{2} \mathrm{H}_{5} \) contains no benzene ring.- Option (d) \( \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OCH}_{3} \) has a benzene ring as part of its structure.

Step 3: Determine Suitability for Electrophilic Substitution

Since electrophilic substitution requires an aromatic ring, option (d) \( \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{OCH}_{3} \) is the only compound with a benzene ring that can undergo electrophilic substitution reactions. Other compounds lack the necessary aromatic system.

Key Concepts

Organic Chemistry

Organic chemistry is a branch of chemistry focused on the study of molecules that contain carbon. Carbon atoms are unique, allowing for the creation of a multitude of diverse and complex structures.
In organic chemistry, you'll explore different types of bonds carbon can form and how it interacts with other elements like hydrogen, oxygen, and nitrogen.
These interactions lead to the formation of organic compounds, which are the building blocks of life.

• Examples include alcohols, ethers, esters, and hydrocarbons.
• Carbon's ability to create strong covalent bonds leads to the formation of stable molecules.
• Organic reactions are categorized based on the nature of the reactants and the products.

Understanding these principles will help in recognizing the properties and reactivities of various organic compounds.

Aromatic Compounds

Aromatic compounds are a fascinating subset of organic compounds defined by their distinct stability and special electronic features.
They are characterized by having a planar ring structure with delocalized electrons, known as conjugation, leading to an "aromatic" stability.
A common example is benzene, a simple aromatic compound with a six-carbon ring and alternating double bonds, contributing to its unique characteristics.

• They follow Huckel's rule, \(4n+2\) pi electrons, to satisfy the aromatic criteria.
• These compounds are not just limited to benzene; heterocyclic aromatics include atoms like nitrogen or oxygen.
• Aromatic compounds undergo specific reactions like electrophilic substitution, maintaining their ring integrity.

This unique property makes aromatic compounds particularly interesting in organic chemistry.

Chemical Reactions

Chemical reactions are the backbone of chemistry, describing processes where substances transform into new substances.
In organic chemistry, reactions are whispers in the world of molecules, helping them transition and evolve.
Electrophilic substitution, a core reaction type for aromatics, involves an electrophile replacing another atom in a molecule, typically hydrogen, while the aromatic ring remains largely unaltered.

• Examples include nitration, halogenation, and sulfonation of aromatics.
• The presence of electron-rich or electron-poor substituents can influence reaction rates.
• Understanding these reactions helps predict product formation and reactivity trends.

By mastering these, you'll gain insight into the transformation of organic compounds.

Benzene Ring

The benzene ring is a foundational element in organic chemistry, especially concerning aromatic compounds.
This hexagonal structure is renowned for its remarkable stability and resonance-delocalized pi electrons.
Benzene is the simplest aromatic hydrocarbon, exhibiting properties that make it a cornerstone in learning about molecular structures and reactivities.

• It has a formula of \(C_6H_6\) and appears as a ring with alternate double bonds, represented using a Kekulé structure.
• Despite the alternating bond character, all carbon-carbon bonds have the same length due to electron delocalization.
• The stability of benzene is such that it prefers substitution over addition, typical of aromatic systems.

Understanding benzene is crucial for anyone delving into the magical world of organic molecules, paving the way for exploring more complex aromatic systems.