Question

An organic compound \(\mathrm{X}\left(\mathrm{MF}: \mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{2}\right)\) on acid hydrolysis gave a carboxylic acid \(\mathrm{Y}\) and an alcohol \(\mathrm{Z}\). Oxidation of \(Z\) with chromic acid produced Y. Identify the compound (X).

Short answer

Oxidation of Z with chromic acid gave Y, and both Y and Z were found to have the same number of carbon atoms. Answer: The structure of the unknown organic compound X is propyl propanoate (C2H5COOCH2CH2CH3).

Step-by-step solution

Identify the functional group of compound X

Since hydrolysis of compound X gives a carboxylic acid Y and an alcohol Z, it indicates that compound X contains an ester functional group. Esters have the general formula RCOOR'. We'll proceed by finding the structure of the ester.

Determine the structures of Y and Z

The molecular formula of X is C6H12O2. Upon acid hydrolysis, it forms a carboxylic acid Y and an alcohol Z. The sum of carbon atoms in Y and Z should be equal to 6. Let the number of carbon atoms in Y be m and the number of carbon atoms in Z be n, then m + n = 6. Oxidation of Z with chromic acid gave Y, which means Z should be a primary alcohol (RCH2OH). Also, since the carboxylic acid and alcohol have the same number of carbons, it leads to m = n. Thus, m = n = 3. Now we know that both Y and Z have 3 carbon atoms each. The carboxylic acid Y is then propanoic acid (C2H5COOH) and the alcohol Z is propan-1-ol (C3H7OH).

Deduce the structure of compound X

With the knowledge of the structures of Y and Z (propanoic acid and propan-1-ol), we can deduce the structure of the ester compound X. The general structure of an ester is RCOOR', and in our case, RCOO part belongs to propanoic acid which is C2H5COO and R' part belongs to propan-1-ol which is CH2CH2CH3. Therefore, the structure of the ester compound X is C2H5COOCH2CH2CH3 (propyl propanoate).

Key concepts

Ester Functional Group

Esters are a fascinating type of organic compound known for their distinct smell, often found in fragrances and flavors. They are characterized by the functional group \( \text{RCOOR'} \). Here, the "\( \text{RCOO} \)" part is the acyl group, while "\( \text{R'} \)" denotes the alkyl group.
These compounds are often formed through a reaction between a carboxylic acid and an alcohol, a process known as esterification. Esters are important both in industrial applications and in biological processes. In the context of the IIT JEE syllabus, understanding ester structures is foundational for tackling various organic chemistry problems.

Hydrolysis Reaction

Hydrolysis is a crucial concept, especially in organic reactions involving esters. It involves breaking down a compound by the addition of water. In this context, ester hydrolysis splits an ester into a carboxylic acid and an alcohol.
This reaction can occur in acidic or basic conditions, known as acid hydrolysis and base hydrolysis (saponification). Acidic hydrolysis reverses the esterification reaction. For the given problem, compound X undergoes acid hydrolysis to yield propanoic acid and propan-1-ol.

• Acid hydrolysis: The ester reacts with water, facilitated by an acid catalyst, to form acid and alcohol.
• Base hydrolysis: Leads to the formation of a carboxylate salt and alcohol.

Oxidation of Alcohols

Oxidation of alcohols is an essential concept in understanding organic transformations. When alcohols oxidize, they typically form ketones, aldehydes, or carboxylic acids.
This process significantly depends on the type of alcohol. In the case of primary alcohols, oxidation results in the formation of aldehydes, which can further oxidize to carboxylic acids. For the problem at hand, propan-1-ol oxidizes to form propanoic acid.

• Primary alcohols like propan-1-ol: Oxidize to aldehydes, then to carboxylic acids.
• Secondary alcohols: Usually oxidize to ketones.
• Tertiary alcohols: Typically resist oxidation without breaking carbon bonds.

Carboxylic Acids

Carboxylic acids are organic acids containing the \( \text{-COOH} \) functional group. Their acidic nature is due to the ability to donate a hydrogen ion from the hydroxyl group.
In organic synthesis, they play a key role as reactants and products, participating in reactions like esterification and hydrolysis.
For the given problem, propanoic acid is formed from the ester hydrolysis of compound X and also through the oxidation of propan-1-ol. It highlights its dual occurrence, showcasing predictable chemical transformations in organic chemistry.

• Structure: Contains a carbonyl (\( \text{C=O} \)) and hydroxyl (\( \text{-OH} \)) group.
• Reactivity: React with alcohols to form esters and with bases to form carboxylate salts.

Primary Alcohols

Primary alcohols contain the \( \text{-OH} \) group attached to a carbon atom that is connected to at most one other carbon. These alcohols are essential in organic synthesis and reactions.
They are highly versatile, as they can be easily oxidized to form aldehydes and further into carboxylic acids. In our initial problem, propan-1-ol served as the primary alcohol that oxidized to form propanoic acid.

• Structure: Characterized by the presence of an alkyl group bonded to the hydroxyl-bearing carbon.
• Reactivity: Readily undergo oxidation, enabling a variety of synthesis pathways.
• Applications: Common in the production of solvents and raw materials for synthesis.