Problem 123 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the following: List I (Reagents) 1\. (CN) 2\. (ONO) 3\. \(\mathrm{NH}_{3}\) 4\. \(\mathrm{AlCl}\) List II (Nature) (i) Neutral nucleophile (ii) electrophile (iii) Ambident nucleophile (iv) both \(\mathrm{El}\) and \(\mathrm{Nu}\) $$ \begin{aligned} &\text { The correct matching is }\\\ &\begin{array}{|c|c|c|c|c|} \hline & \text { 1 } & \text { 2 } & \text { 3 } & \text { 4 } \\ \hline \text { a } & \text { (i) } & \text { (iii) } & \text { (ii) } & \text { (iv) } \\ \hline \text { b } & \text { (iii) } & \text { (iii) } & \text { (i) } & \text { (ii) } \\ \hline \text { c } & \text { (iv) } & \text { (iii) } & \text { (iii) } & \text { (i) } \\ \hline \text { d } & \text { (ii) } & \text { (iv) } & \text { (i) } & \text { (iii) } \\ \hline \end{array} \end{aligned} $$

Step-by-Step Solution

Answer

The correct matching is option 'c'.

Step 1: Identifying (CN)

The reagent \((CN)\) is a cyanide ion, which is an ambident nucleophile due to its ability to bind through either the carbon or nitrogen atom. This matches with (iii) Ambident nucleophile.

Step 2: Identifying (ONO)

The reagent \((ONO)\) is typically seen as a nitrito group, which is also an ambident nucleophile as it can attach through either the oxygen or the nitrogen atom. Thus, it matches with (iii) Ambident nucleophile.

Step 3: Identifying NH3

Ammonia, \(\mathrm{NH}_3\), is a neutral molecule that can donate a lone pair of electrons, classifying it as a neutral nucleophile. Therefore, it matches with (i) Neutral nucleophile.

Step 4: Identifying AlCl

\(\mathrm{AlCl}\) can act as both an electrophile and a nucleophile, which means it matches with (iv) both \(\mathrm{El}\) and \(\mathrm{Nu}\).

Step 5: Finding the Matching Set

Now that each reagent has been correctly identified, match them with the correct options from the given sets:- \((CN)\) matches (iii)- \((ONO)\) matches (iii)- \(\mathrm{NH}_3\) matches (i)- \(\mathrm{AlCl}\) matches (iv)Comparing with the options given, the correct match is found in option 'c'.

Key Concepts

Cyanide Ion

The cyanide ion, represented as \((CN)\), is a fascinating and versatile ion. It's known as an ambident nucleophile due to its ability to attack from two different sites. It can form bonds either through the carbon atom or the nitrogen atom. When engaging in chemical reactions, the cyanide ion can choose the most appropriate site for bonding based on the conditions of the reaction and the participating elements.
Whether the carbon or nitrogen is used to bond can significantly alter the course of a reaction and the properties of the resulting compound.

• The carbon in \((CN)\) typically forms strong bonds with metals or carbon atoms in organic molecules.
• The nitrogen, less frequently, can also serve as an attachment point, making it a versatile player in chemical synthesis.

Being an ambident nucleophile opens up many pathways for reaction mechanisms, emphasizing its importance in both organic and inorganic chemistry.

Ambident Nucleophile

An ambident nucleophile is a special type of chemical entity that has multiple sites available for electron donation. This unique property allows ambident nucleophiles to participate in two different chemical pathways, leading to diverse reaction products.
The versatility of ambident nucleophiles can sometimes be a challenge as they may yield a mixture of products when reacted in a less controlled environment.

• Cyanide ion is a classic example, with both carbon and nitrogen as potential sites for bonding.
• Another example is the nitrito group \((ONO)\), which can bond either through its oxygen or nitrogen atoms.

When designing a synthetic strategy, it's crucial to consider which site will most likely participate in the reaction to achieve the desired chemical transformation. This choice can be influenced by reaction conditions like solvent, temperature, and the nature of the substrate.

Neutral Nucleophile

Neutral nucleophiles are molecules that carry no overall charge but have lone pairs of electrons ready to be donated in a chemical reaction. Ammonia, \(\text{NH}_3\), is a prime example of a neutral nucleophile. It is equipped with a lone pair of electrons, making it capable of forming strong covalent bonds by donating this electron pair to electrophilic centers in other compounds.
The neutrality of these nucleophiles offers a distinct advantage as it minimizes charge repulsion during reactions.

• Being neutral, ammonia can easily participate in coordination chemistry and organic synthesis.
• The lone pair on nitrogen enables it to attack positively charged or electron-deficient sites effectively.

The understanding of neutral nucleophiles is essential in grasping a wide range of chemical reactions, particularly those involving substitution and coordination. Their ability to interact with various electrophiles without carrying an electrical charge allows for diverse and efficient reaction pathways.