For the reation given below, identify X in the reaction
`CH_3C -= CCH_3 overset(X)rarr CH_3COCOCH_3`

Options

A. `K_2Cr_2O_7//H_2SO_4`
B. `O_2`
C. `O_3, Zn//H_2O`
D. `HNO_3`

Answer

To identify the reagent X in the reaction

\[ CH_3C \equiv CCH_3 \overset{X}{\rightarrow} CH_3COCOCH_3 \]

we need to analyze the transformation taking place in the reaction.

### Step 1: Identify the starting material and product
The starting material is 2-butyne (CH₃C≡CCH₃), which is an alkyne. The product is 3-pentanone (CH₃COCOCH₃), which contains a carbonyl group (C=O) and suggests that some form of oxidation or cleavage is occurring.

**Hint:** Look for a reagent that can cleave the triple bond and introduce carbonyl groups.

### Step 2: Understand the reaction type
The reaction involves the conversion of an alkyne to a compound with carbonyl groups. This suggests that we are dealing with ozonolysis, a reaction where ozone (O₃) is used to cleave double or triple bonds.

**Hint:** Recall that ozonolysis is commonly used for alkenes and alkynes to produce carbonyl compounds.

### Step 3: Write the ozonolysis reaction
In ozonolysis, the alkyne reacts with ozone (O₃) to form an intermediate that can rearrange and subsequently be reduced. The typical reducing agents used after ozonolysis are zinc (Zn) and water (H₂O).

**Hint:** Remember that after ozonolysis, a reducing agent is often required to convert the ozonide into carbonyl compounds.

### Step 4: Combine the reagents
Thus, the reagent X that facilitates this transformation is a combination of ozone (O₃) followed by zinc (Zn) in the presence of water (H₂O).

**Hint:** Think about the sequence of ozonolysis followed by reduction when identifying the reagents.

### Conclusion
The correct identification of X in the reaction is:

\[ X = O_3 \text{ (ozone) and Zn/H₂O} \]

This means the complete reaction can be summarized as:

\[ CH_3C \equiv CCH_3 \overset{O_3, Zn/H_2O}{\rightarrow} CH_3COCOCH_3 \]

### Final Answer
X is O₃ (ozone) followed by Zn and H₂O.

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