Identify reactant (X) in the given reaction sequence.
`CH_(3)COCH_(3)+X to (CH_(3))_(3)C-OMg-Cl overset(H_(2)O) to (CH_(3))_(3)C-OH+Mg{:(" OH"),("/"),("\"),(" Cl"):}`

Options

A. `CH_(3)MgCl`
B. `CH_(3)COCl+Mg`
C. `MgCl_(2)`
D. `CH_(3)CH_(2)MgCl`

Answer

To identify the reactant (X) in the given reaction sequence, we will analyze the reaction step by step.

### Step 1: Understanding the Reactants and Products
The reaction starts with acetone, which has the molecular formula \( CH_3COCH_3 \). The product after reacting with reactant (X) is a compound that contains a tertiary alcohol structure, specifically \( (CH_3)_3C-OH \).

### Step 2: Recognizing the Nature of the Reaction
The product \( (CH_3)_3C-OH \) indicates that a Grignard reagent is likely involved in the reaction. Grignard reagents are typically formed from alkyl or aryl halides reacting with magnesium in dry ether.

### Step 3: Identifying the Grignard Reagent
The Grignard reagent that would lead to the formation of the tertiary alcohol \( (CH_3)_3C-OH \) must have a structure that, when reacted with acetone, results in the addition of a \( CH_3 \) group to the carbonyl carbon of acetone.

### Step 4: Formulating the Grignard Reagent
The Grignard reagent that can be used here is \( CH_3MgCl \). This reagent contains the \( CH_3 \) group, which will act as a nucleophile and attack the electrophilic carbonyl carbon of acetone.

### Step 5: Writing the Overall Reaction
The overall reaction can be summarized as follows:
1. Acetone \( (CH_3COCH_3) \) reacts with \( CH_3MgCl \) (the Grignard reagent).
2. This results in the formation of a magnesium alkoxide intermediate \( (CH_3)_3C-OMgCl \).
3. Upon hydrolysis with water, this intermediate produces the tertiary alcohol \( (CH_3)_3C-OH \) and magnesium hydroxide \( Mg(OH)Cl \).

### Conclusion
Thus, the reactant (X) in the given reaction sequence is identified as:
**X = \( CH_3MgCl \)** (Methyl magnesium chloride).

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