Problem 14 - A Complete Resource Book in Chemistry for JEE Main

Question

Which is formed when \(\left(\mathrm{CH}_{3}\right)_{4} \mathrm{NOH}\) is heated? (a) \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{NH}_{2}\) (b) \(\left(\mathrm{CH}_{2}\right)_{3} \mathrm{~N}\) (c) \(\mathrm{CH}_{3} \mathrm{NH}_{2}\) (d) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{~N}\)

Step-by-Step Solution

Answer

Option (d) \((\mathrm{CH}_3)_3\mathrm{N}\) is formed when \((\mathrm{CH}_3)_4 \mathrm{NOH}\) is heated.

Step 1: Understand the Starting Compound

The compound given is \( (\mathrm{CH}_3)_4 \mathrm{NOH} \), which is known as tetra-methyl ammonium hydroxide, \( \left[(\mathrm{CH}_3)_4\mathrm{N}^+\right]\mathrm{OH}^-\).

Step 2: Analyze Heating Effects

Upon heating, tetra-methyl ammonium hydroxide decomposes, losing water \((\mathrm{H}_2\mathrm{O})\) and forming trimethylamine \((\mathrm{CH}_3)_3\mathrm{N}\).

Step 3: Write the Decomposition Reaction

The decomposition of \( (\mathrm{CH}_3)_4 \mathrm{NOH} \) can be represented as:\[(\mathrm{CH}_3)_4 \mathrm{NOH} \rightarrow (\mathrm{CH}_3)_3 \mathrm{N} + \mathrm{H}_2\mathrm{O}\]

Step 4: Identify the Correct Option

The product formed is trimethylamine \((\mathrm{CH}_3)_3\mathrm{N}\), which corresponds to option (d).

Key Concepts

Tetra-methyl Ammonium Hydroxide

Tetra-methyl ammonium hydroxide, chemically represented as \((\mathrm{CH}_3)_4 \mathrm{NOH}\), is an important compound in organic chemistry. It's composed of a nitrogen atom surrounded by four methyl groups \((\mathrm{CH}_3)\) and a hydroxide ion \((\mathrm{OH}^-)\). This structure makes it a type of quaternary ammonium compound, which are known for their significance in both industrial and laboratory settings. - These compounds are often used as phase transfer catalysts in chemical reactions.- They help reactants interact in different phases (like oil and water).When Tetra-methyl ammonium hydroxide is heated, its structure undergoes a chemical change. This process is influenced by the stability of the resulting products upon thermal decomposition.

Trimethylamine

Trimethylamine \((\mathrm{CH}_3)_3\mathrm{N}\) is the product formed when Tetra-methyl ammonium hydroxide decomposes. It is an organic compound classified as an amine, an important family of nitrogen-containing substances. - The molecule consists of a nitrogen atom bonded to three methyl groups, giving it a distinctive fishy odor.- It is colorless and typically found as a gas at room temperature but can be liquefied.Trimethylamine is used in a variety of applications:

• As a precursor in the production of chemicals like quaternary ammonium compounds.
• In the food industry to impart a 'fishy' flavor in certain products.
• It's commonly studied in biological research due to its formation during the decomposition of animal matter.

The formation of Trimethylamine from Tetra-methyl ammonium hydroxide showcases an interesting chemical transformation wherein a complex molecule simplifies to a basic amine through the loss of water.

Chemical Reaction

A chemical reaction involves the transformation of one or more substances into different substances. In the case of Tetra-methyl ammonium hydroxide, the process is thermal decomposition, a type of reaction driven by heat. This specific reaction can be understood in the following way:When heated, the compound \((\mathrm{CH}_3)_4 \mathrm{NOH}\) breaks down by losing water \((\mathrm{H}_2\mathrm{O})\) and releasing trimethylamine \((\mathrm{CH}_3)_3\mathrm{N}\). This can be represented by the equation:\[ (\mathrm{CH}_3)_4 \mathrm{NOH} \rightarrow (\mathrm{CH}_3)_3 \mathrm{N} + \mathrm{H}_2\mathrm{O}\]In chemical reactions like these:

• The bonds between atoms are broken in the starting material (reactants), leading to the formation of new bonds in the products.
• Energy, in the form of heat, facilitates the breaking of these bonds, allowing for the rearrangement of atoms.
• These transformations are often used to understand how substances change under different conditions, crucial for applications across chemistry, biology, and engineering.

Understanding this decomposition reaction not only helps in predicting the behavior of similar compounds under heat but also enhances the overall grasp on reaction mechanisms and energy changes in chemistry.