Given below are two statements.
Statement I: C2H5OH and AgCN both can generate nucleophile.
Statemen

Q: Why does KCN form nitriles while AgCN forms isonitriles?

KCN is predominantly ionic, releasing free $CN^-$ ions. Since a C-C bond is stronger than a C-N bond, the attack happens through carbon, forming nitriles. AgCN is covalent, so the carbon is bonded to silver and blocked. The attack is forced through the nitrogen's lone pair, forming isonitriles.

Q: Is $C_2H_5OH$ a strong or weak nucleophile?

Ethanol is a weak, neutral nucleophile. It doesn't have a full negative charge, but the lone pairs on its oxygen atom allow it to participate in nucleophilic substitution reactions, such as solvolysis.

Q: What exactly is an ambidentate nucleophile?

An ambidentate nucleophile is a species that has two different nucleophilic centers (atoms with lone pairs or negative charge) through which it can attack. Examples include the cyanide ion ($CN^-$) and the nitrite ion ($NO_2^-$).

Q: Does the solvent affect the product in KCN/AgCN reactions?

While the solvent plays a crucial role in determining whether the reaction follows an $S_N1$ or $S_N2$ pathway, the primary reason for the different products (nitrile vs isonitrile) here is the intrinsic ionic vs covalent nature of the reagents themselves.

Q: Can AgCN ever form nitriles?

AgCN predominantly forms isonitriles as the major product. While trace amounts of nitriles might form due to minor ionic character, for all practical and exam purposes, AgCN yields isonitriles.

Question

Given below are two statements.
Statement I: $C_2H_5OH$ and AgCN both can generate nucleophile.
Statement II: KCN and AgCN both will generate nitrile nucleophile with all reaction conditions.
Choose the most appropriate option.

Options:

(A) Statement I is true but statement II is false.

(B) Both statements I and II are true.

(C) Statement I is false but statement II is true.

(D) Both statements I and II are false.

Sigma Percentile · Accepted Answer

### The Nucleophile's Quest

Imagine you are a positively charged carbon atom, desperately seeking electrons to complete your octet. Who do you call? A **nucleophile**!

A nucleophile is an electron-rich species, armed with either a negative charge or a lone pair of electrons, ready to donate them to an electron-deficient center. In this problem, we are tasked with evaluating the nucleophilic potential of three different molecules: ethanol ($C_2H_5OH$), potassium cyanide (KCN), and silver cyanide (AgCN). Let's break down their behavior step by step.

### Decoding Statement I: The Hidden Lone Pairs

Statement I claims that both ethanol and silver cyanide can generate nucleophiles. Let's put ethanol under the microscope.

At first glance, $C_2H_5OH$ is a neutral molecule. However, if we look closely at the oxygen atom, we find two unshared pairs of electrons—**lone pairs**. These lone pairs make ethanol a capable, albeit neutral, nucleophile.

Now, what about silver cyanide (AgCN)? Even though it is a covalent compound, the nitrogen atom in the cyanide group possesses a lone pair of electrons. This lone pair is perfectly capable of attacking an electrophile. Therefore, both ethanol and AgCN can indeed act as nucleophiles. Statement I stands absolutely true!

### Decoding Statement II: The Tale of Two Cyanides

Statement II introduces a fascinating comparison between KCN and AgCN, claiming both will generate nitrile nucleophiles. This is where the chemistry gets incredibly elegant.

Let's start with potassium cyanide (KCN). KCN is an **ionic compound**. When it dissolves, it completely dissociates into $K^+$ and $CN^-$ ions.

The cyanide ion ($CN^-$) is an **ambidentate nucleophile**, meaning it has two potential attacking centers: the carbon atom and the nitrogen atom. However, a carbon-carbon bond is thermodynamically much stronger and more stable than a carbon-nitrogen bond. Given the choice, the attack will predominantly occur through the carbon atom, leading to the formation of **nitriles** (also known as cyanides).

### The Covalent Trap of Silver Cyanide

Now, let's turn our attention to silver cyanide (AgCN). Unlike KCN, AgCN is predominantly **covalent**.

The bond between the silver atom and the carbon atom is strong and does not readily dissociate in solution. Because the carbon atom is firmly tethered to the silver atom, it is effectively blocked from participating in any nucleophilic attack!

So, what happens? The molecule is forced to use its only available electron source: the lone pair on the nitrogen atom. Consequently, the attack occurs exclusively through nitrogen, resulting in the formation of **isonitriles** (or isocyanides).

### The Final Verdict

By understanding the fundamental difference in the nature of the bonds—ionic in KCN versus covalent in AgCN—we can easily see the flaw in Statement II.

AgCN does not generate nitriles; it generates isonitriles. Therefore, Statement II is false.

Our final conclusion is clear: Statement I is true, and Statement II is false. This beautiful interplay of ionic and covalent character is a classic concept in organic chemistry, and mastering it will give you a significant edge in your exams!

Animated Solution for Chemistry - Haloalkanes & Haloarenes: Given below are two statements. Statement I: $C_{2} H_{5} O H$ and AgCN both can generate nucleophile. Statement II: KCN and AgCN both will generate nitrile nucleophile with all reaction conditions. Choose the most appropriate option.

Select Answer:

Visualized Solution

$N u c l eo p hi l es$

$S t a t e m e n t I$

$K C N (I o ni c)$

$A g C N (C o v a l e n t)$

$C o n c l u s i o n$

$A mbi d e n t a t e N u c l eo p hi l es$

The Sigma Insight: Haloalkanes & Haloarenes

The Nucleophile's Quest

Decoding Statement I

Decoding Statement II

The Covalent Trap of Silver Cyanide

The Final Verdict

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