The alkyne which gives pyruvic acid `(CH_(3)COCOOH)` on oxidation with alk. `KMnO_(4)` is -

Options

A. `CH-=CH`
B. `CH_(3)C-=CH`
C. `CH_(3)-C-=C-CH_(3)`
D. `CH_(3)-CH_(2)-C-=CH`

Answer

To determine the alkyne that gives pyruvic acid (CH₃COCOOH) upon oxidation with alkaline KMnO₄, we can follow these steps:

### Step 1: Understand the Structure of Pyruvic Acid
Pyruvic acid has the formula CH₃COCOOH. It contains three carbon atoms and a carboxylic acid functional group. The structure can be represented as:
```
O
||
CH₃-C-COOH
```
This indicates that we need to find an alkyne that can yield this structure upon oxidation.

### Step 2: Identify the Required Carbon Skeleton
Since pyruvic acid has three carbon atoms, we need an alkyne that can provide this number of carbons after oxidation. The alkyne must have a structure that allows for the formation of a carbonyl group (C=O) and a hydroxyl group (OH) after oxidation.

### Step 3: Consider Possible Alkynes
Let’s consider the possible alkynes:
1. 1-butyne (CH₃C≡CCH₃)
2. 2-butyne (CH₃C≡CCH₃)
3. 1-pentyne (CH₃C≡CCH₂CH₃)
4. 2-pentyne (CH₃C≡CCH₂CH₃)

### Step 4: Oxidation with KMnO₄
When alkynes are oxidized with alkaline KMnO₄, they undergo syn-dihydroxylation, resulting in the formation of diols. For our target, we need to check which alkyne can lead to the formation of pyruvic acid.

#### Testing 2-butyne:
- The structure of 2-butyne is CH₃C≡CCH₃.
- Upon oxidation with KMnO₄, it will yield:
- CH₃C(OH)-C(OH)CH₃
- This will further dehydrate to yield CH₃C(=O)C(OH) which is pyruvic acid.

### Step 5: Conclusion
The alkyne that gives pyruvic acid upon oxidation with alkaline KMnO₄ is **2-butyne (CH₃C≡CCH₃)**.