The number of products obtained in the following reaction is: Reaction:
The number of products obtained in the following reaction is: Reaction:
Show Hint
1. Secondary alcohols can undergo both oxidation and elimination
2. Base promotes β-elimination in benzylic alcohols
3. Heating drives both reactions forward
4. No rearrangement products expected in this case
- 1
- 3
- 2
- 4
The Correct Option is C
Approach Solution - 1
The given reaction involves the base-catalyzed (NaOH) decomposition of 1-phenylethanol (Ph-CH(OH)-CH$_3$) under heating ($\Delta$). This leads to two main products through different pathways:
Product 1: Acetophenone (Ph-CO-CH$_3$)
- Formed via oxidation of the alcohol
- The base abstracts a proton from the -OH group
- Resulting in formation of a carbonyl group
Product 2: Styrene (Ph-CH=CH$_2$)
- Formed via elimination reaction
- NaOH abstracts a proton from the β-carbon
- Leads to formation of a double bond Mechanistic pathways:
1. Oxidation pathway:
\[ \text{Ph-CH(OH)-CH}_3 \rightarrow \text{Ph-CO-CH}_3 \]
2. Elimination pathway:
\[ \text{Ph-CH(OH)-CH}_3 \rightarrow \text{Ph-CH=CH}_2 \]
Why not other options?
- Only these two major products form under these conditions
- No significant side products are expected
- The reaction doesn't proceed to complete decomposition
Approach Solution -2
Given Reaction:
The reactants are:
- Acetaldehyde (CH3CHO)
- Phenylacetaldehyde (C6H5CH2CHO)
- Under aldol condensation conditions (NaOH, heat)
This is a classic crossed aldol condensation under basic conditions with heat. Both aldehydes have α-hydrogens and can act as both enolate donors and electrophilic acceptors. Therefore, multiple condensation products are possible.
Possible Products:
The enolate can form from either aldehyde, and attack either:
- Self-condensation of acetaldehyde
- Self-condensation of phenylacetaldehyde
- Cross-condensation: acetaldehyde enolate + phenylacetaldehyde
- Cross-condensation: phenylacetaldehyde enolate + acetaldehyde
- Enolate from acetaldehyde attacking phenylacetaldehyde
- Enolate from phenylacetaldehyde attacking acetaldehyde
Final Answer: 2
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