Which of the following compounds on basic hydrolysis will gives formaldehyde ?

Options

A. `CHCl_3`
B. `CH_3-CHCl_3`
C. `CH_2Cl_2`
D. `"CCl"_4`

Answer

To solve the question of which compound gives formaldehyde upon basic hydrolysis, we will analyze each of the given compounds step by step.

### Step 1: Understanding Basic Hydrolysis
Basic hydrolysis involves the reaction of a compound with water in the presence of a strong base (like NaOH or KOH). This process typically involves the breaking of bonds in the compound and the formation of new bonds with hydroxide ions (OH⁻) from the base.

**Hint:** Remember that basic hydrolysis usually replaces halogens with hydroxyl groups.

### Step 2: Analyzing Each Compound
We will analyze each compound provided in the question to see which one produces formaldehyde (HCHO) upon hydrolysis.

#### Compound A: CHCl3 (Chloroform)
1. **Reaction with Base:** CHCl3 reacts with OH⁻ to replace Cl atoms with OH groups.
2. **Intermediate Formation:** This leads to the formation of a geminal diol (CH(OH)3).
3. **Dehydration:** The geminal diol is unstable and loses water to form HCOOH (formic acid), not formaldehyde.

**Conclusion:** CHCl3 does not yield formaldehyde.

**Hint:** Look for the stability of the intermediate formed during hydrolysis.

#### Compound B: CH3CCl3 (Trichloroethane)
1. **Reaction with Base:** Similar to chloroform, CH3CCl3 reacts with OH⁻, replacing Cl atoms with OH groups.
2. **Intermediate Formation:** This leads to a geminal diol.
3. **Dehydration:** The geminal diol loses water and forms CH3C(=O)OH (acetic acid), not formaldehyde.

**Conclusion:** CH3CCl3 does not yield formaldehyde.

**Hint:** Consider the number of halogen atoms and how they affect the product.

#### Compound C: CH2Cl2 (Dichloromethane)
1. **Reaction with Base:** CH2Cl2 reacts with OH⁻, replacing Cl atoms with OH groups.
2. **Intermediate Formation:** This forms a geminal diol (CH(OH)2).
3. **Dehydration:** The geminal diol loses water, resulting in HCHO (formaldehyde).

**Conclusion:** CH2Cl2 yields formaldehyde.

**Hint:** Identify the final product after dehydration of the geminal diol.

#### Compound D: CCl4 (Carbon Tetrachloride)
1. **Reaction with Base:** CCl4 is a non-polar compound and does not undergo hydrolysis easily under basic conditions.
2. **Conclusion:** It does not yield any product, let alone formaldehyde.

**Hint:** Consider the polarity of the compound and its reactivity with water.

### Final Answer
After analyzing all the compounds, the only compound that gives formaldehyde upon basic hydrolysis is **CH2Cl2 (Dichloromethane)**.

**Correct Answer:** C (CH2Cl2)