Write the structural formulas for the products formed when 3-heptyne reacts with `KMnO_(4)` under ?
(i) neutral condition at room temp.
(ii) alkaline or acidic condition at higher temp.

Answer

To solve the problem of determining the products formed when 3-heptyne reacts with KMnO₄ under different conditions, we will analyze each case step by step.

### Step 1: Identify the structure of 3-heptyne
3-heptyne is an alkyne with the following structure:
- It has a triple bond between the third and fourth carbon atoms.
- The structural formula can be represented as follows:

```
CH₃-CH₂-C≡C-CH₂-CH₂-CH₃
```

### Step 2: Reaction under neutral conditions at room temperature
When 3-heptyne reacts with KMnO₄ in a neutral medium at room temperature, it undergoes oxidation. The triple bond will be converted into two carbonyl (C=O) groups.

1. The triple bond (C≡C) is oxidized to form a double bond with oxygen (C=O) on both carbons involved in the triple bond.
2. The resulting product will have two carbonyl groups at the 3rd and 4th positions.

The structural formula of the product formed under these conditions is:

```
CH₃-CH₂-C(=O)-C(=O)-CH₂-CH₂-CH₃
```

### Step 3: Reaction under alkaline or acidic conditions at higher temperature
When 3-heptyne reacts with KMnO₄ in alkaline or acidic conditions at a higher temperature, the reaction leads to cleavage of the triple bond and further oxidation.

1. The triple bond breaks, and each carbon involved in the bond is oxidized to form a carboxylic acid (COOH) and a carbonyl compound (C=O).
2. Specifically, the products formed will be:
- One carboxylic acid at the 3rd carbon (C₃H₇COOH)
- One carbonyl compound at the 4th carbon (C₄H₈O)

The structural formulas of the products formed under these conditions are:

```
CH₃-CH₂-C(=O)OH (3-heptanoic acid)
CH₃-CH₂-C(=O)-CH₂-CH₂-CH₃ (butan-2-one)
```

### Summary of Products
1. **Neutral Conditions at Room Temperature:**
- Product: 3,4-diketone
- Structural Formula: `CH₃-CH₂-C(=O)-C(=O)-CH₂-CH₂-CH₃`

2. **Alkaline or Acidic Conditions at Higher Temperature:**
- Products: 3-heptanoic acid and butan-2-one
- Structural Formulas:
- `CH₃-CH₂-C(=O)OH` (3-heptanoic acid)
- `CH₃-CH₂-C(=O)-CH₂-CH₂-CH₃` (butan-2-one)