Problem 18 - A Complete Resource Book in Chemistry for JEE Main

Question

Formaldehyde \(+\mathrm{NH}_{3} \longrightarrow \mathrm{Y}\). The product \(\mathrm{Y}\) is (a) hexamethylene tetramine (b) formamide (c) paraformaldehyde (d) methanol

Step-by-Step Solution

Answer

The product Y is hexamethylene tetramine.

Step 1: Identify the Reactants

In the given reaction, we have formaldehyde (also known as methanal) and ammonia (\(\mathrm{NH}_3\)) as the reactants. Formaldehyde has the chemical formula \(\mathrm{CH}_2\mathrm{O}\), and ammonia is \(\mathrm{NH}_3\).

Step 2: Determine Possible Reaction Outcomes

Consider the reaction between formaldehyde and ammonia. A well-known product of this reaction is hexamethylene tetramine, which forms through a specific type of condensation reaction where several formaldehyde and ammonia molecules interact.

Step 3: Analyze Product Formation

The reaction of formaldehyde (\(\mathrm{CH}_2\mathrm{O}\)) with ammonia (\(\mathrm{NH}_3\)) forms a compound called hexamethylene tetramine (also known as hexamine or methenamine), with the formula \((\mathrm{CH}_2)_6\mathrm{N}_4\). This happens as the nitrogen atoms form a bond with the carbon atoms from the formaldehyde.

Step 4: Choose the Correct Product Option

Based on formaldehyde reacting with ammonia, the appropriate product of the reaction is hexamethylene tetramine. Thus, the correct choice among the options provided is (a) hexamethylene tetramine.

Key Concepts

Formaldehyde

Formaldehyde, also known as methanal, is a fundamental compound in organic chemistry. It is the simplest form of an aldehyde, with the chemical formula \(\mathrm{CH}_2\mathrm{O}\). This compound is characterized by its pungent odor. Formaldehyde is highly reactive due to its carbonyl group, allowing it to partake in various chemical reactions.

Some important properties of formaldehyde include:

• It is a colorless gas at room temperature.
• Formaldehyde has a boiling point of -19 °C.
• Synthetic uses involve polymerization and condensation reactions with different compounds like ammonia.

These properties make formaldehyde a crucial compound in industrial applications and a common starting material in chemical synthesis.

Hexamethylene Tetramine

Hexamethylene tetramine, often called hexamine or methenamine, is an interesting compound formed from the reaction between formaldehyde and ammonia. It has the chemical formula \((\mathrm{CH}_2)_6\mathrm{N}_4\). This compound involves a structure where nitrogen atoms bond intricately with the carbon from formaldehyde.

Here are some key details about hexamethylene tetramine:

• It is a white crystalline solid at room temperature.
• This compound is used as a medication for urinary tract infections, exploiting its ability to form a weak acid in acidic conditions.
• It also finds applications in the manufacturing of explosives and as a fuel source in portable stoves.

Hexamethylene tetramine's formation is a wonderful example of how multiple simpler molecules can combine to form more complex structures.

Condensation Reaction

In the context of organic chemistry, a condensation reaction is a process where two molecules combine, typically resulting in the elimination of a small molecule such as water. This reaction type is essential in forming larger molecules from smaller building blocks.

In the case of formaldehyde and ammonia, the condensation process results in the creation of hexamethylene tetramine. Here's what happens:

• Several molecules of formaldehyde and ammonia interact to form a new, more complex molecule.
• The products created often contain the atoms from the smaller molecules arranged in a new pattern.

Condensation reactions are crucial for the synthesis of various polymers and are a vital mechanism for the transformation of simpler organic compounds into more complex structures.

Ammonia

Ammonia is a colorless gas with a characteristic pungent smell, familiar to many due to its widespread use in cleaning products. Its chemical formula is \(\mathrm{NH}_3\), and it serves as the other reactant in the reaction with formaldehyde.

Ammonia has various interesting properties and uses:

• Ammonia acts as a base and can neutralize acids.
• It is highly soluble in water, forming ammonium hydroxide, which is a common cleaning agent.
• Ammonia is pivotal in agriculture as a fertilizer and in the synthesis of explosives, fibers, and plastics.

In chemical reactions, nitric atoms in ammonia can readily form bonds with carbon atoms, facilitating the formation of complex compounds, such as hexamethylene tetramine from formaldehyde and ammonia.