`"Hex-3-ynal" overset((1)NaBH_(4))to overset((2)PBr_(3))to overset((3)"Mg/Ether")to overset((4)CO_(2))to overset((5)H^(oplus))to(X)`, formed product X will be:

Options

A.
B.
C.
D.

Answer

To solve the problem step by step, we will follow the reactions as described in the question.

### Step 1: Identify the starting compound
The starting compound is **Hex-3-ynal**, which is an aldehyde with a triple bond. The structure can be represented as follows:

```
CH3-CH2-C≡C-CHO
```

### Step 2: Reduction with NaBH4
When Hex-3-ynal is treated with **NaBH4** (sodium borohydride), it acts as a reducing agent. The aldehyde group (CHO) will be reduced to a primary alcohol (CH2OH). The structure after this reaction will be:

```
CH3-CH2-C≡C-CH2OH
```

### Step 3: Reaction with PBr3
Next, the product from Step 2 is treated with **PBr3** (phosphorus tribromide). This reagent converts the alcohol (CH2OH) into a bromide (CH2Br). The structure after this reaction will be:

```
CH3-CH2-C≡C-CH2Br
```

### Step 4: Formation of Grignard Reagent
Now, the product from Step 3 is treated with **Mg in ether**. This will form a Grignard reagent by inserting magnesium into the carbon-bromine bond. The structure will now be:

```
CH3-CH2-C≡C-CH2MgBr
```

### Step 5: Reaction with CO2
The Grignard reagent formed in Step 4 is then treated with **CO2** (carbon dioxide). The nucleophilic carbon (from the Grignard reagent) will attack the electrophilic carbon of CO2, leading to the formation of a carboxylic acid. The structure after this reaction will be:

```
CH3-CH2-C≡C-CH2COO^-
```
(Note: The carboxylate ion is formed at this stage.)

### Step 6: Hydrolysis with H+
Finally, the product from Step 5 is treated with **H+** (acidic workup), which will convert the carboxylate ion into a carboxylic acid (COOH). The final product X will be:

```
CH3-CH2-C≡C-COOH
```

### Final Structure of Product X
The final product X is **Hex-3-ynoic acid**, which has the following structure:

```
CH3-CH2-C≡C-COOH
```

### Summary of Steps
1. Start with Hex-3-ynal (aldehyde with a triple bond).
2. Reduce with NaBH4 to form an alcohol.
3. Convert the alcohol to a bromide with PBr3.
4. Form a Grignard reagent with Mg in ether.
5. React with CO2 to form a carboxylate.
6. Hydrolyze with H+ to form the final carboxylic acid.