When diborane undergoes complete methylation, the number of hydrogen atoms replaced is

Options

A. 6
B. 2
C. 4
D. 3

Answer

To solve the problem of how many hydrogen atoms are replaced when diborane undergoes complete methylation, we can follow these steps:

### Step 1: Understand the Structure of Diborane
Diborane (B2H6) consists of two boron atoms and six hydrogen atoms. The structure includes:
- 2 bridge hydrogens (H) that connect the two boron atoms.
- 4 terminal hydrogens (H) that are bonded to the boron atoms.

### Step 2: Identify the Methylation Process
Methylation involves the substitution of hydrogen atoms with methyl groups (CH3). In this case, diborane will react with methyl chloride (CH3Cl) to replace hydrogen atoms with methyl groups.

### Step 3: Determine Which Hydrogens are Replaced
When diborane undergoes complete methylation:
- The 4 terminal hydrogens are replaced by 4 methyl groups (CH3).
- The 2 bridge hydrogens remain unchanged during this process.

### Step 4: Calculate the Number of Hydrogen Atoms Replaced
Since only the terminal hydrogens are replaced:
- Total hydrogen atoms in diborane = 6
- Hydrogen atoms replaced = 4 (the terminal hydrogens)

### Conclusion
When diborane undergoes complete methylation, the number of hydrogen atoms replaced is **4**.

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