Problem 126 - A Complete Resource Book in Chemistry for JEE Main

Question

$$ \begin{aligned} &\text { 6. Match the following }\\\ &\begin{array}{ll} \hline \text { Column-I (Substrate) } & \text { Column-II (Reagent) } \\ \hline \text { (a) } \mathrm{R}-\mathrm{CH}_{2}-\mathrm{NH}_{2} & \text { (p) } \mathrm{KMn} \mathrm{O}_{4}, \mathrm{H}^{+} \\ \text {(b) } \mathrm{R}_{2} \mathrm{CH}-\mathrm{NH}_{2} & \text { (q) } \mathrm{H}_{2} \mathrm{SO}_{5} \\ \text { (c) } \mathrm{R}_{2} \mathrm{NH} & \text { (r) } \mathrm{O}_{3} \\ \text { (d) } \mathrm{R}_{3} \mathrm{~N} & \text { (s) } \mathrm{H}_{2} \mathrm{O}_{2} \\ & \text { (t) } \mathrm{HNO}_{2} \\ \hline \end{array} \end{aligned} $$

Step-by-Step Solution

Answer

(a) matches with (t), (b) does not directly match, (c) matches with (q), (d) does not directly match any.

Step 1: Identify the functional groups in Column-I

In this step, you'll need to look at each substrate given in Column-I and identify the functional groups present. - (a) \( \mathrm{R}-\mathrm{CH}_{2}-\mathrm{NH}_{2} \): This is a primary amine.- (b) \( \mathrm{R}_{2} \mathrm{CH}-\mathrm{NH}_{2} \): This is a secondary amine.- (c) \( \mathrm{R}_{2} \mathrm{NH} \): Also a secondary amine but without a direct hydrogen on carbon attached to nitrogen.- (d) \( \mathrm{R}_{3} \mathrm{~N} \): This is a tertiary amine.

Step 2: Identify the reactivity of reagents in Column-II

Understand what transformation each reagent in Column-II typically performs:- (p) \( \mathrm{KMnO_4, H^+} \): Used for oxidation reactions.- (q) \( \mathrm{H_2SO_5} \): Strong oxidizing agent, peroxymonosulfuric acid.- (r) \( \mathrm{O_3} \): Ozonolysis, typically cleaves carbon-carbon double bonds.- (s) \( \mathrm{H_2O_2} \): Mild oxidizing agent.- (t) \( \mathrm{HNO_2} \): Reacts with primary amines to form alcohols.

Step 3: Match substrates with appropriate reagents

Based on the reactivity types identified, match each substrate with the reagent that it reacts with:- (a) \( \mathrm{R}-\mathrm{CH}_{2}-\mathrm{NH}_{2} \) and (t) \( \mathrm{HNO_2} \): Primary amines react with \( \mathrm{HNO_2} \) to form diazonium salts which can further decompose to alcohols.- (b) \( \mathrm{R}_{2} \mathrm{CH}-\mathrm{NH}_{2} \) doesn't react significantly with any considering stability, secondary amines often engage in reactions like nitrosation in acidic mediums which are not in question.- (c) \( \mathrm{R}_{2} \mathrm{NH} \) and (q) \( \mathrm{H_2SO_5} \): They can undergo oxidation to form corresponding nitroso compounds.- (d) \( \mathrm{R}_{3} \mathrm{~N} \) matches with none directly given its stable nature; theoretically \( \mathrm{HNO_2} \) as nitrous acid can form nitric acid under certain conditions but not applicable here.

Key Concepts

Amines

Amines are organic compounds derived from ammonia by replacement of one or more hydrogen atoms with alkyl or aryl groups. They are categorized based on the number of carbon-containing groups attached to the nitrogen atom:

• Primary amines have one alkyl or aryl group attached to the nitrogen atom, like in the case of \( \mathrm{R}-\mathrm{CH}_2-\mathrm{NH}_2 \)
• Secondary amines have two carbon groups attached, such as \( \mathrm{R}_2\mathrm{CH}-\mathrm{NH}_2 \) where the nitrogen is bonded to two hydrocarbon chains.
• Tertiary amines feature three alkyl or aryl groups connected to the nitrogen, like \( \mathrm{R}_3\mathrm{~N} \). These are more stable due to the substitution of all hydrogen atoms.

Amines can participate in a variety of reactions due to their lone pair of electrons on nitrogen, making them basic and nucleophilic. Understanding the structure of amines helps in predicting and matching these compounds with reactive partners in chemical reactions.

Oxidation reactions

Oxidation reactions in organic chemistry involve the increase in the oxidation state of a molecule. This is often visualized as the addition of oxygen or the removal of hydrogen. Amines can undergo oxidation to form different compounds:

• Primary amines can be oxidized to nitroso or nitro compounds, but typically react to form diazonium salts in the presence of nitrous acid.
• Secondary amines can be oxidized to form nitroso compounds using agents like \( \mathrm{H_2SO_5} \), which is a powerful oxidizing agent.
• Tertiary amines are generally resistant to oxidation due to lack of available hydrogen atoms.

Oxidizing agents like \( \mathrm{KMnO_4} \) and \( \mathrm{H_2O_2} \) function differently based on their strength and the substrate involved. Knowing the type of amine and the available oxidizing reagent is crucial for predicting the outcome of oxidation reactions.

Reagent compatibility

Reagent compatibility is key in determining successful and safe chemical reactions. It refers to the ability of a reagent to react with a specific functional group without causing unwanted side reactions. Various reagents are compatible with different functional groups in organic compounds:

• Primary amines are compatible with \( \mathrm{HNO_2} \) for the formation of diazonium salts.
• Secondary amines find a match with strong oxidizing agents like \( \mathrm{H_2SO_5} \) for oxidation to specific oxidized products.
• Tertiary amines are less reactive due to the absence of hydrogen atoms, hence fewer reagents are compatible for reactions.

Understanding reagent compatibility is essential for selecting the correct reagent to carry out specific chemical reactions with particular substrates.

Functional groups

Functional groups are specific groups of atoms within molecules that determine the characteristic chemical reactions of those molecules. Recognizing these groups is crucial in predicting reaction types and outcomes:

• Amine functional groups include -NH2, -NHR, and -NR2. They determine the basicity and reactivity of amine-containing compounds with other reagents.
• Oxidizing agents can either directly interact with these groups leading to transformations such as the conversion of amines to nitroso or nitro derivatives.
• Knowing the functional groups helps chemists understand and manipulate organic reactions, selecting suitable reagents, and predicting reaction paths.

Being aware of the nature of functional groups allows for detailed insights into the reactivity and compatibility of organic molecules with various reagents.