Problem 18 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Bakelite is obtained from phenol by reacting with: [Main Online April 25, 2013] (a) Acetal (b) \(\mathrm{CH}_{3} \mathrm{CHO}\) (c) \(\mathrm{HCHO}\) (d) Chlorobenzene

Step-by-Step Solution

Answer

(c) \(\mathrm{HCHO}\)

Step 1: Understanding the Key Ingredients for Bakelite

To determine what phenol reacts with to produce Bakelite, we need to know that Bakelite is a type of plastic and one of the earliest synthetic polymers. Its synthesis involves the reaction of phenol with formaldehyde under certain conditions.

Step 2: Recognizing Chemical Notation

Examine the chemical notations given in the options:- Acetal is often the product of the reaction between an aldehyde and an alcohol.- \(\(\mathrm{CH}_{3}\mathrm{CHO}\)\)\ is acetaldehyde.- \(\(\mathrm{HCHO}\)\)\ is formaldehyde.- Chlorobenzene is a compound formed by chlorination of benzene.

Step 3: Identifying Formaldehyde

The synthesis of Bakelite involves the reaction of phenol with formaldehyde. Formaldehyde's chemical notation is \(\(\mathrm{HCHO}\)\). It reacts with phenol to form a phenol-formaldehyde resin, which is Bakelite.

Step 4: Selecting the Correct Option

Based on the chemical knowledge that Bakelite is made from phenol and formaldehyde, identify which option corresponds to formaldehyde. Option (c) is \(\(\mathrm{HCHO}\)\), which is formaldehyde, so it is the correct answer.

Key Concepts

Understanding Phenol

Phenol is an organic compound known for its distinct aromatic structure. It consists of a hydroxyl group \( (-OH) \) bonded to a benzene ring. This compound is known for its antiseptic properties and plays a significant role in the production of plastics.

In the synthesis of Bakelite, phenol acts as a starting material. Its reactive nature makes it suitable for forming complex structures with other compounds. When phenol reacts with formaldehyde, it undergoes a transformation that is crucial for creating polymeric materials like Bakelite. This synthesis highlights the ability of phenol to combine with other chemicals, forming long chains that turn into solid, heat-resistant materials.

• Composed of a hydroxyl group attached to a benzene ring.
• Important in plastic synthesis due to its reactivity.
• Combines with formaldehyde to create phenol-formaldehyde resins.

Understanding phenol's structure and properties reveals why it is so effective in forming durable, synthetic polymers.

Formaldehyde's Role in Polymer Formation

Formaldehyde, depicted as \( \mathrm{HCHO} \), is a simple aldehyde with a wide range of industrial uses. Its reactivity with various organic compounds makes it ideal for different chemical reactions, including polymerization.

In the creation of Bakelite, formaldehyde is key to forming the stable, cross-linked structure inherent in phenol-formaldehyde resins. When phenol and formaldehyde are reacted together, they initially form a pre-polymer. This intermediate then proceeds to polymerize further, resulting in the dense, three-dimensional network that characterizes Bakelite.

• Formaldehyde is a simple aldehyde (\( \mathrm{HCHO} \)).
• Essential for polymer chemistry due to its high reactivity.
• Combines with phenol to initiate polymer formation.

Formaldehyde's reactivity facilitates the synthesis of polymers that are heat-resistant, strong, and versatile, making it indispensable in the production of early synthetic plastics like Bakelite.

Synthetic Polymers and Their Importance

Synthetic polymers are large, man-made molecules composed of repeating structural units. These polymers are created through polymerization processes that link small monomers together. One of the earliest synthetic polymers developed was Bakelite, which is formed from phenol and formaldehyde.

Bakelite is renowned for its durability, heat resistance, and electrical non-conductivity, which made it preferable for products like electrical insulators and radio casings. The advent of Bakelite marked the beginning of an era where synthetic materials could be tailored to meet diverse industrial and consumer needs.

• Bakelite was one of the first synthetic polymers.
• Synthetic polymers are formed by polymerizing monomers.
• They offer unique properties like heat resistance and durability.

The development of synthetic polymers, exemplified by Bakelite, showcases the potential of combining organic chemistry with industrial innovation to create materials with properties required by modern technology.