Problem 27 - A Complete Resource Book in Chemistry for JEE Main

Question

A yellow product is formed when an organic compound \(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}\) is warmed with aqueous sodium carbonate and iodine solution. The product formed is (a) iodoform (b) sodium iodate (c) sodium iodide (d) adduct of \(\mathrm{Nal}\) and \(\mathrm{C}_{3} \mathrm{H}_{8} \mathrm{O}\)

Step-by-Step Solution

Answer

The yellow product formed is (a) iodoform.

Step 1: Identify the Reaction

The reaction involves an organic compound with a formula \( \mathrm{C}_{3}\mathrm{H}_{8}\mathrm{O} \), sodium carbonate, and iodine. This corresponds to the iodoform reaction, which typically occurs with compounds containing a methyl ketone group.

Step 2: Determine the Type of Organic Compound

The compound \( \mathrm{C}_{3}\mathrm{H}_{8}\mathrm{O} \) could be a secondary alcohol like isopropanol or a ketone like propanone. Both can undergo iodoform reactions, but the yellow product is an indication of the iodoform reaction specific to methyl ketones or convertible alcohols.

Step 3: Observe the Product Color

The problem states that a yellow product is formed. This is characteristic of the formation of iodoform (\( \mathrm{CHI}_3 \)), a yellow precipitate, confirming an iodoform reaction.

Step 4: Match with the Given Options

The yellow product formed by the reaction is consistent with iodoform \( \mathrm{CHI}_3 \). Among the provided options, the correct answer that describes iodoform is option (a).

Key Concepts

Organic Chemistry

Organic Chemistry is the study of carbon-based compounds and their reactions. It focuses primarily on molecules that contain carbon-hydrogen bonds. Understanding these molecules is essential because they form the backbone of many substances around us.

In Organic Chemistry, reactions are important as they describe how these compounds transform. This branch of chemistry helps us decipher various processes, including the Iodoform Reaction. By understanding Organic Chemistry, chemists can predict reactions and the compounds they produce, ultimately providing insight into processes from medicinal chemistry to energy production. When a reaction occurs, it's often because certain bonds within a molecule break and new bonds form, leading to a rearrangement of atoms and a chemical change.

• Carbon's role is crucial as it can form up to four stable covalent bonds.
• Other elements involved include hydrogen, oxygen, nitrogen, and halogens like iodine.

This grounding helps us make sense of why certain reactions, like the one producing iodoform, happen the way they do.

Methyl Ketone

A Methyl Ketone is a type of organic compound characterized by the presence of a carbonyl group (C=O) linked to a methyl group (CH₃). It is important in chemical reactions, especially the iodoform reaction. This reaction is particularly useful for identifying compounds that contain a methyl ketone structure.

The presence of a methyl group adjacent to the carbonyl group means that when such compounds react with iodine in an alkaline solution (like sodium hydroxide), a specific series of reactions occurs, transforming the compound and leading to the formation of iodoform. This transformation is marked by the production of a yellow precipitate, which is the triiodomethane (iodoform).

• Methyl ketones are found in various natural and synthetic substances, including fragrances and pharmaceuticals.
• Typical examples are acetophenone and acetone.

If a substance reacts positively in an iodoform test, it indicates the presence of a methyl ketone or an alcohol that can be oxidized to one.

Chemical Reaction Identification

Chemical Reaction Identification is a process by which chemists determine the type of reaction taking place. This involves examining the reactants, the conditions under which they react, and the products formed.

The iodoform reaction mentioned in the exercise is one such method of identification. By observing characteristics such as color change—here, the formation of a yellow precipitate—chemists can infer that the reaction involves a methyl ketone. This specific reaction is useful because it allows the identification of certain alcohols and ketones by the simple observation of color.

Identification plays a crucial role in organic chemistry as it helps verify the presence of specific functional groups within a molecule.

• It involves comparing observed data with known reaction behavior.
• Tools used include indicators, pH papers, or observing changes like precipitation or gas formation.

By understanding and identifying reactions, chemists can decode complex chemical systems and explore new synthetic pathways.