Product obtained when benzaldehyde and acetophenone undergo cross aldol condensation is

Options

A. 1, 4 – Diphenylprop -2- en -1- one
B. 1,3 - Diphenylprop -2- en -1- one
C. 1,3- Diphenylprop -1- ene -2- one
D. 1, 4 – Diphenylprop -1- ene -2- one

Answer

To solve the question regarding the product obtained when benzaldehyde and acetophenone undergo cross aldol condensation, we can follow these steps:

### Step 1: Identify the Reactants
The reactants given are:
- Benzaldehyde (C6H5CHO)
- Acetophenone (C6H5COCH3)

### Step 2: Understand the Aldol Condensation Process
Aldol condensation involves the reaction of two carbonyl compounds (aldehydes or ketones) in the presence of a base, leading to the formation of β-hydroxy carbonyl compounds, which can further dehydrate to form α,β-unsaturated carbonyl compounds.

### Step 3: Analyze the Reactants for Alpha Hydrogens
- **Benzaldehyde** has no alpha hydrogens (it has a carbonyl group directly attached to a benzene ring).
- **Acetophenone** has three alpha hydrogens (the methyl group attached to the carbonyl).

### Step 4: Determine Which Reactant Acts as the Nucleophile
Since benzaldehyde lacks alpha hydrogens, it cannot undergo self-condensation. Therefore, it will act as the electrophile, while acetophenone will act as the nucleophile.

### Step 5: Form the Enolate Ion
The acetophenone will lose one of its alpha hydrogens to form an enolate ion. This enolate ion will then attack the carbonyl carbon of benzaldehyde.

### Step 6: Form the β-Hydroxy Carbonyl Compound
The reaction will yield a β-hydroxy carbonyl compound. The structure can be represented as follows:
- The enolate ion from acetophenone attacks the carbonyl carbon of benzaldehyde, leading to the formation of a β-hydroxy ketone.

### Step 7: Dehydrate the β-Hydroxy Carbonyl Compound
The β-hydroxy compound can then lose a water molecule (H2O) to form an α,β-unsaturated carbonyl compound.

### Step 8: Write the Final Product Structure
The final product of the cross aldol condensation between benzaldehyde and acetophenone will have the following structure:
- The product will be 1,3-diphenylprop-2-en-1-one.

### Step 9: Determine the IUPAC Name
The IUPAC name of the product is:
- **1,3-diphenylprop-2-en-1-one**

### Summary of the Product
The product obtained when benzaldehyde and acetophenone undergo cross aldol condensation is **1,3-diphenylprop-2-en-1-one**.

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