The products of the reaction of HCHO and PhCHO in presence of concentrated base are

Options

A. `HCH_2OH +PhCOO^(-)`
B. `HCOO^(-) + PhCH_2OH`
C. `PhCOOCH_3`
D. `HCOOCH_2Ph`

Answer

To solve the question regarding the products of the reaction between HCHO (formaldehyde) and PhCHO (benzaldehyde) in the presence of a concentrated base, we will follow these steps:

### Step 1: Identify the Reaction Type
The reaction between two different aldehydes (HCHO and PhCHO) in the presence of a strong base is known as a **cross-aldol condensation** reaction. However, since both aldehydes do not have alpha hydrogens, they undergo a **cross-Canizzaro reaction** instead.

**Hint:** Remember that the Canizzaro reaction occurs when aldehydes lack alpha hydrogens.

### Step 2: Understand the Reactants
- **HCHO (Formaldehyde)**: It has the structure H2C=O.
- **PhCHO (Benzaldehyde)**: It has the structure C6H5CHO (where C6H5 is the phenyl group).

**Hint:** Visualize the structures of the aldehydes to understand their reactivity.

### Step 3: Analyze the Mechanism
In a cross-Canizzaro reaction:
- One aldehyde gets oxidized to a carboxylate ion, while the other gets reduced to an alcohol.
- The strong base (OH⁻) acts as a nucleophile and attacks the carbonyl carbon of the more electrophilic aldehyde.

**Hint:** Identify which aldehyde is more electrophilic based on the substituents.

### Step 4: Determine Electrophilicity
- **Benzaldehyde (PhCHO)** is more electrophilic than formaldehyde (HCHO) because the phenyl group is electron-withdrawing, making the carbonyl carbon more positive.
- Therefore, the hydroxide ion (OH⁻) will attack formaldehyde (HCHO) to form a carboxylate ion.

**Hint:** Compare the electron-withdrawing effects of the groups attached to the carbonyl carbon.

### Step 5: Identify the Products
1. **From HCHO**: The reaction will yield the carboxylate ion from formaldehyde:
- HCHO + OH⁻ → HCOO⁻ (formate ion)

2. **From PhCHO**: The reaction will yield phenyl alcohol:
- PhCHO + OH⁻ → C6H5CH2OH (benzyl alcohol)

**Hint:** Write down the products clearly, indicating the oxidation and reduction processes.

### Final Answer
The products of the reaction between HCHO and PhCHO in the presence of concentrated base are:
- **Formate ion (HCOO⁻)**
- **Benzyl alcohol (C6H5CH2OH)**

Thus, the correct answer is option two: **HCOO⁻ and C6H5CH2OH**.