Problem 124 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the following: List I (Compound) 1\. Acetamide 2\. Phthalimide 3\. Benzonitrile 4\. Grignard reagent List II (Nature) (i) Acidic (ii) Basic (iii) Nautral The correct matching is: 1 2 3 4 (a) (iii) (i) (i) (iii) (b) (iii) (i) (iii) (ii) (c) (i) (ii) (ii) (iii) (d) (ii) (iii) (i) (ii)

Step-by-Step Solution

Answer

The correct matching is (b) (iii) (i) (iii) (ii).

Step 1: Identify the Nature of Acetamide

Acetamide is an amide, derived from acetic acid. It has a neutral character because the nitrogen atom is involved in resonance with the carbonyl group, rendering it weakly acidic if at all. Therefore, Acetamide is best described as (iii) Neutral.

Step 2: Analyze the Properties of Phthalimide

Phthalimide contains two carboxyl groups connected through the imide group. It tends to donate a proton due to the presence of the imide group, making it acidic in nature. Thus, Phthalimide is (i) Acidic.

Step 3: Determine the Nature of Benzonitrile

Benzonitrile is an aromatic nitrile, which is generally neutral in its chemical behavior. It does not react in an acidic or basic manner, so Benzonitrile is also (iii) Neutral.

Step 4: Examine the Properties of Grignard Reagent

Grignard reagents are organometallic compounds that contain magnesium. They are typically strong bases and are very reactive. Thus, the Grignard reagent corresponds to (ii) Basic.

Key Concepts

Acetamide Neutrality

Acetamide is an intriguing compound in the world of chemistry due to its neutral nature. It is an amide derived from acetic acid, and its chemical structure features a nitrogen atom closely interacting with a carbonyl group. This interaction is known as resonance.

• Resonance delocalizes electron density, which reduces the ability of acetamide to donate or accept protons.
• Thus, acetamide does not exhibit notable acidic or basic properties.

In simple terms, its resonance creates a balanced, neutral state. Unlike typical acids or bases, acetamide does not readily release hydrogen ions (protons) or react with acids to form salts. This property is why acetamide is classified under neutral compounds in chemical reactivity assessments.

Phthalimide Acidity

Phthalimide is recognized for its acidic attributes owing to its structure. It contains two carboxyl groups linked by an imide group, making it an aromatic compound. The presence of the imide group plays a critical role in phthalimide's behavior.

• The imide's nitrogen atom is bonded to two carbonyl groups which tend to stabilize the negative charge once a proton is released.
• This ability to release a proton contributes to the compound's acidic nature.

Phthalimide can effectively react with basic compounds to form salts, demonstrating that it is indeed capable of donating a proton. Its acidity makes it useful in organic synthesis, especially in the formation of N-substituted compounds.

Benzonitrile Neutrality

Benzonitrile is interesting because, despite being an aromatic nitrile, it displays neutrality in its chemical interactions. The nitrile group within benzonitrile comprises a carbon triple-bonded to a nitrogen atom, which is strong and stable.

• This structural configuration results in limited reactivity with either acids or bases.
• As a result, benzonitrile rarely participates in typical acid-base reactions.

Its neutrality serves significant roles in industrial applications, including being a solvent for synthetic processes and a precursor for the production of valuable pharmaceuticals.

Grignard Reagent Basicity

Grignard reagents are fundamental in organic chemistry for their basicity and reactivity. These organometallic compounds, which include magnesium bonded to a carbon atom and other organic groups, exhibit strong basic characteristics.

• The magnesium-metal bond in Grignard reagents is highly polar, allowing the carbon anion to act as a strong base.
• They are effective in nucleophilic additions, often used to create alcohols from carbonyl compounds.

The base-paired reactivity of Grignard reagents makes them invaluable for creating complex organic molecules. Due to their high reactivity, they must be handled under controlled conditions to prevent inadvertent reactions with moisture or atmospheric substances.