Question

Answer the question on the basis of the passage given below:
Alcohols and phenol are formed when a hydrogen atom in a hydrocarbon, aliphatic and aromatic respectively, is replaced by \(-OH\). The substitution of a hydrogen atom in a hydrocarbon by an alkoxy or aryloxy group forms ethers.
Alcohols and phenol consist of two parts, an alkyl/aryl group and a hydroxyl group. The properties of alcohols and phenols are primarily due to the hydroxyl group. The nature of alkyl and aryl groups simply modify these properties. Alcohol react both as nucleophiles and electrophiles whereas in phenols, the reactions that take place on the aromatic ring are electrophilic substitution reactions.
In the following reaction, compounds A and C are:
\[ \text{CH}_3\text{CHO} + \text{CH}_3\text{MgBr} \xrightarrow{(i) H_2O, (ii) H_2SO_4} \xrightarrow{\text{Hydroboration, Oxidation}} \text{B} \xrightarrow{\Delta} \text{C} \] Choose the correct answer from the options given below:

• A. identical
• B. positional isomers
• C. functional isomers
• D. optical isomers

Hint:

Functional isomers are compounds that have the same molecular formula but differ in the type of functional group they contain. For example, alcohols and aldehydes can be functional isomers.

Answer 1

The Correct Option is C

Let's go through the steps of the reaction: 
1. Step 1: Addition of Grignard Reagent (CH₃MgBr) to Acetaldehyde (CH₃CHO): 
This reaction forms an alcohol (compound A) by a nucleophilic attack of the Grignard reagent on the carbonyl group of acetaldehyde, leading to the formation of CH₃CH(OH)CH₃ (a secondary alcohol). 
2. Step 2: Hydroboration and Oxidation (Reaction of Compound A with Hydroboration Reagent and Oxidizing Agent): 
This step would form a hydroxy aldehyde or a primary alcohol from compound A, which may result in compound B.

3. Step 3: Oxidation (Heating to form Compound C): 
Upon heating with a strong acid (H₂SO₄) or in the presence of an oxidizing agent, compound B undergoes oxidation or dehydration, yielding compound C (a functional isomer). 
Thus, compounds A and C are functional isomers. These are compounds that have the same molecular formula but differ in the functional groups attached to them (e.g., alcohol vs aldehyde). 
Reactions:
- Grignard Reaction: \[ \text{CH}_3\text{CHO} + \text{CH}_3\text{MgBr} \rightarrow \text{CH}_3\text{CH(OH)CH}_3 \] - Hydroboration and Oxidation: \[ \text{R-CH}_2\text{OH} + \text{B}_2\text{H}_6 \xrightarrow{\text{oxidation}} \text{R-CHOH} \quad \text{(Alcohol to Aldehyde or Ketone)} \]