Problem 16 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Match the following, choosing one item from column \(\mathbf{X}\) and the appropriate item from column \(\mathbf{Y}\). [Multiple Concepts, (i) Decarboxylation (a) Addition reaction (ii) Ozonolysis (b) Soda lime (iii) Williamson's synthesis (c) Structure of alkene (iv) Dichloroethylene (d) Ether

Step-by-Step Solution

Answer

(i) \to (b), (ii) \to (c), (iii) \to (d), (iv) \to (a).

Step 1: Understand Decarboxylation

Decarboxylation is the chemical reaction that removes a carboxyl group and releases carbon dioxide (CO₂). It often involves the use of soda lime as a reagent to carry out the reaction. Therefore, the match for decarboxylation is \((i) \to (b)\).

Step 2: Understand Ozonolysis

Ozonolysis is a reaction where ozone (O₃) is used to cleave alkenes, eventually giving multiple smaller molecules. It's primarily used to determine the structure of alkenes by breaking the double bonds. Therefore, the match for ozonolysis is \((ii) \to (c)\).

Step 3: Understand Williamson's Synthesis

Williamson’s synthesis is a method used to produce ethers. It is a nucleophilic substitution reaction involving an alkoxide and an alkyl halide. Therefore, the match for Williamson’s synthesis is \((iii) \to (d)\).

Step 4: Understand Dichloroethylene

Dichloroethylene represents a specific type of alkene that contains chlorine. It is involved in addition reactions due to its double bond nature, where additional atoms can be added across the double bond. Therefore, the match for dichloroethylene is \((iv) \to (a)\).

Key Concepts

Decarboxylation

Decarboxylation is a fascinating chemical reaction where a carboxyl group is removed from a molecule. This process releases carbon dioxide \( \text{CO}_2 \) as a byproduct, which can simplify the molecular structure. One of the common agents used in decarboxylation is soda lime, a mixture typically composed of calcium oxide (CaO) and sodium hydroxide (NaOH). These reagents facilitate the reaction efficiently.

Decarboxylation happens in several organic compounds, especially carboxylic acids. It is often utilized in laboratory settings to reduce the complexity of molecules by removing unwanted carboxyl groups.

This reaction finds its relevance in various fields such as pharmaceuticals, where it's used in drug synthesis.

• It's crucial for transforming carboxylic acids into simpler hydrocarbons.
• This reaction plays a key role in metabolic and synthetic pathways.

The simple and straightforward nature of decarboxylation makes it an essential reaction to understand in chemistry.

Ozonolysis

Ozonolysis is an oxidative cleavage reaction crucial in organic chemistry. It involves the use of ozone \( \text{O}_3 \) to break down alkenes into smaller molecules. This typically results in the formation of compounds like aldehydes, ketones, or carboxylic acids depending on the solvent and conditions used.

Ozonolysis is particularly important when it comes to determining the structure of alkenes. By breaking down the double bonds, chemists can infer the arrangement of carbon atoms in the original alkene. This makes ozonolysis a powerful tool in structural analysis.

• Key for identifying unknown double-bond positions in organic compounds.
• Useful in preparative processes to create various types of carbonyl compounds.

This reaction shows how seemingly complex molecules can be split into simpler components, facilitating easier analysis and research.

Williamson's Synthesis

Williamson's Synthesis is an essential method for producing ethers in organic chemistry. It involves a nucleophilic substitution reaction where an alkoxide ion reacts with an alkyl halide. The result is the formation of an ether, showcasing the versatility of this reaction.

This synthesis is particularly significant due to its ability to form complex, asymmetric ethers, which are valuable across various industrial and pharmaceutical applications. It's a straightforward yet powerful reaction that transforms readily available starting materials into valuable compounds.

• Excellent for creating varied ether structures.
• Relies on the high nucleophilicity of alkoxides.

The simplicity and efficiency of Williamson's synthesis make it a cornerstone reaction for ether production.

Addition Reaction

Addition reactions play a pivotal role in modifying unsaturated molecules, such as alkenes and alkynes. In these reactions, new atoms are added to the carbon-carbon multiple bonds, transforming them into single bonds.

An addition reaction is particularly significant with alkenes, like dichloroethylene, resulting in the addition of more atoms or functional groups. This is essential for creating more complex molecules from simple unsaturated hydrocarbons.

• Enables the functionalization of hydrocarbons.
• Utilizes the reactivity of double or triple bonds.

Understanding addition reactions is crucial for synthesizing a wide range of organic compounds, expanding the diversity of synthetic possibilities in chemistry.