Question

If \(\mathrm{S}\) is a polymer and all products are major product in the following reaction sequences, then correct options ' is/are (A) Both (Q) and \((\mathrm{R})\) are soluble in aq. \(\mathrm{NaHCO}_{3}\) (B) Formation of (S) is step growth polymerisation (C) (P) will give yellow crystal with \(\mathrm{NaOI}\) (D) (Q) has common name terephthalic acid.

Short answer

Based on the provided information, we cannot generate the short answer as the exact reaction sequences are not provided. However, to analyze the given statements, you would need to identify the properties and functional groups of the compounds involved, understand their reactions, and apply this knowledge to determine the truth of each statement.

Step-by-step solution

Analyzing Option A

If both Q and R are soluble in aqueous sodium bicarbonate (NaHCO3), it means they should be acidic in nature, as NaHCO3 is a weak base. We would identify the acidic functional groups in Q and R and then determine if they can react with NaHCO3 and be soluble.

Analyzing Option B

For the formation of S to be a step-growth polymerization, the reactions to form S should involve the reactions between functional groups of the reactants. We should be able to track the sequence of reactions that lead to the formation of the polymer by checking for the presence of functional groups capable of undergoing step growth polymerization (e.g., carboxylic acids, amines, or alcohols).

Analyzing Option C

To determine if P will give yellow crystals with NaOI, we need to identify the functional group in P that can react with sodium iodide (NaOI) and if it would produce a compound that appears as yellow crystals. This could involve understanding the chemical behavior of P and knowing the suitable experiments or tests for each functional group present.

Analyzing Option D

For Q to have the common name terephthalic acid, it should have the molecular structure of terephthalic acid, which is benzene-1,4-dicarboxylic acid. By identifying the structure of Q, we can confirm whether or not it is terephthalic acid. In the given exercise, we cannot provide the step-by-step solution, as the reaction sequences are not provided. However, by understanding each option and knowing the characteristics of the involved compounds and the reactions they undergo, we can analyze the given statements in relation to the actual reactions.

Key concepts

Solubility in Aqueous Sodium Bicarbonate

When we talk about solubility in aqueous sodium bicarbonate, we’re primarily dealing with the characteristic of certain compounds to dissolve in a weakly basic solution. Sodium bicarbonate, commonly known as baking soda, reacts with substances that have acidic properties. Essentially, when an organic compound containing acidic functional groups, such as carboxylic acids, comes into contact with sodium bicarbonate, a chemical reaction occurs forming water and carbon dioxide, the latter often seen as effervescence.

Therefore, the solubility of a compound in aqueous sodium bicarbonate can be an indicative test for the presence of acidic functional groups in a molecule. For example, a carboxylic acid would react to form water-soluble carboxylate ions and carbon dioxide gas. This property is useful not only in laboratory testing but also when considering the environmental implications of polymer degradation and the interactions between polymers and their surroundings.

Terephthalic Acid

Terephthalic acid is an important organic compound known for its utility in the production of polyesters, such as polyethylene terephthalate (PET). It is a white, crystalline substance, which is not very soluble in water but can react with aqueous sodium bicarbonate to form its corresponding salt. Structurally, it is defined as benzene-1,4-dicarboxylic acid, meaning it has a benzene ring with two carboxylic acid groups at the 1 and 4 positions.

As an aromatic dicarboxylic acid, terephthalic acid is a prime candidate for step growth polymerization, in which it would typically react with a diol (a compound with two hydroxyl groups) to form long polymer chains. This process leads to the production of materials that have desirable properties for a variety of applications, such as plastic bottles, fibers for clothing, and films for packaging.

Functional Group Reactions

Functional group reactions are at the heart of organic chemistry. They involve the transformation of specific groups of atoms within a molecule that has characteristic chemical behaviors. For students, understanding these reactions is crucial for JEE (Joint Entrance Examination) chemistry, as they lay the foundation for synthesizing complex molecules and polymers.

In the context of the textbook exercise, functional group reactions would allow us to predict the behaviors of the compounds and their solubility, ability to polymerize, and reaction with test agents like sodium iodide (NaOI). For instance, the hydroxyl (-OH) and carboxyl (-COOH) groups undergo specific reactions which are predictable and formulaic, such as esterification or amidation. Knowing these can help students make accurate predictions about chemical behavior during their exams.

Polymer Chemistry for JEE

Polymer chemistry is a significant topic in the field of chemistry, especially for students preparing for the JEE, as polymers form a major part of modern materials science. Understanding the principles of polymerization, like step-growth and addition polymerization, is essential for developing a strong foundational knowledge.

Step-growth polymerization, for example, involves the chemical reaction between molecules with functional groups that can link together directly, forming polymer chains. The exercise points to this type of polymerization, hinting at the formation of a polyester through sequential reactions. Students should become familiar with the mechanisms of various polymerization processes, how they differ, and their practical applications to excel in this portion of the JEE chemistry syllabus.