In the given reaction `CH_3-C-=Noverset((i)CH_3MgBr"(excess)")rarr(X)` (X) will be

Options

A. `CH_3-overset(O)overset(||)C-H`
B. `CH_3-overset(O)overset(||)C-CH_3`
C. `CH_3-underset(CH_3)underset(|)overset(OH)overset(|)C-CH_3`
D. `CH_3-overset(O)overset(||)C-NH_2`

Answer

To solve the question regarding the reaction of methyl cyanide with excess methyl magnesium bromide, we will follow a step-by-step approach to identify the compound X formed in the reaction.

### Step-by-Step Solution:

1. **Identify the Reactants**:
The reactants are methyl cyanide (CH₃-C≡N) and excess methyl magnesium bromide (CH₃MgBr).

**Hint**: Recognize the functional groups in the reactants; methyl cyanide has a nitrile group while methyl magnesium bromide is a Grignard reagent.

2. **Nucleophilic Addition Reaction**:
The Grignard reagent (CH₃MgBr) acts as a nucleophile. The carbon atom in the nitrile (C≡N) is electron-deficient and will be attacked by the nucleophilic methyl group (CH₃⁻) from the Grignard reagent.

**Hint**: Remember that Grignard reagents are strong nucleophiles and will attack electrophilic centers.

3. **Formation of an Intermediate**:
Upon the attack, the triple bond (C≡N) breaks, and we form an intermediate compound:
\[ CH₃-C(=N-MgBr)CH₃ \]
This intermediate has a double bond with nitrogen and a magnesium bromide complex.

**Hint**: Visualize the structure of the intermediate to understand the bonding changes.

4. **Hydrolysis of the Intermediate**:
The intermediate is then hydrolyzed (usually with water or an acid) to convert the nitrile group into a ketone. This results in the formation of acetone (CH₃C(=O)CH₃).

**Hint**: Hydrolysis typically converts functional groups; in this case, a nitrile is converted to a ketone.

5. **Further Reaction with Excess Grignard Reagent**:
Since we have excess CH₃MgBr, the acetone (CH₃C(=O)CH₃) will react again with the Grignard reagent. The carbonyl carbon of acetone is also electrophilic and will be attacked by another methyl group from CH₃MgBr.

**Hint**: Understand that the carbonyl carbon is a site for further nucleophilic attack.

6. **Formation of the Final Product**:
This reaction leads to the formation of a tertiary alcohol after hydrolysis:
\[ CH₃C(OH)(CH₃)CH₃ \]
This compound is 2-methylpropan-2-ol.

**Hint**: Identify the final structure by counting the carbon atoms and their connectivity.

7. **Conclusion**:
The final product X formed from the reaction is 2-methylpropan-2-ol.

**Final Answer**: The compound X is 2-methylpropan-2-ol.

### Summary of the Steps:
1. Identify reactants.
2. Recognize the nucleophilic addition.
3. Form an intermediate.
4. Hydrolyze to form acetone.
5. React with excess Grignard reagent.
6. Form the final product.
7. Conclude with the identification of compound X.