What is Z in the following sequence of reactions ?
2-methyl -2-bromo propane `overset(Mg)underset(dry ether")to X overset(H_2O)to Z`.

Options

A. Propane
B. 2 - methyl propene
C. 2 - methyl propane
D. 2 - methyl butane

Answer

To determine what Z is in the given sequence of reactions, let's break down the steps involved in the transformation of 2-methyl-2-bromopropane to Z.

### Step-by-Step Solution:

1. **Identify the Starting Compound**:
The starting compound is 2-methyl-2-bromopropane, which has the molecular structure:
\[ \text{(CH}_3)_2\text{CBrCH}_3 \]
This can be represented as:
\[ \text{C}_3\text{H}_7\text{Br} \]

2. **Reaction with Magnesium in Dry Ether**:
When 2-methyl-2-bromopropane reacts with magnesium (Mg) in dry ether, it forms a Grignard reagent. The reaction can be represented as:
\[ \text{(CH}_3)_2\text{CBrCH}_3 + \text{Mg} \xrightarrow{\text{dry ether}} \text{(CH}_3)_2\text{C}(\text{MgBr})\text{CH}_3 \]
This Grignard reagent is:
\[ \text{(CH}_3)_2\text{C}(\text{MgBr})\text{CH}_3 \]

3. **Reaction with Water**:
The Grignard reagent formed (X) is then treated with water (H₂O). Grignard reagents react with water to form hydrocarbons and magnesium hydroxide bromide. The reaction can be represented as:
\[ \text{(CH}_3)_2\text{C}(\text{MgBr})\text{CH}_3 + \text{H}_2\text{O} \rightarrow \text{(CH}_3)_2\text{C}(\text{H})\text{CH}_3 + \text{Mg(OH)Br} \]
Here, the Grignard reagent abstracts a proton from water, resulting in the formation of:
\[ \text{(CH}_3)_2\text{C}\text{H}\text{CH}_3 \]

4. **Identify the Final Product Z**:
The final product Z is:
\[ \text{(CH}_3)_2\text{C}\text{H}\text{CH}_3 \]
This structure corresponds to 2-methylpropane (also known as neopentane).

### Conclusion:
Thus, the final product Z is **2-methylpropane**.