Give IUPAC name of : `CH_(3)-CH=CH-CHO` .

Explanation

To provide a step-by-step solution for the IUPAC naming of the compound `CH₃-CH=CH-CHO`, we can follow these steps:

### Step 1: Identify the longest carbon chain
The first step in naming any organic compound is to identify the longest continuous carbon chain. In this case, the longest chain consists of 4 carbon atoms.

### Step 2: Determine the functional group
Next, we need to identify the functional group present in the compound. Here, we have an aldehyde group (-CHO) at one end of the carbon chain.

### Step 3: Number the carbon chain
We will number the carbon chain starting from the end closest to the functional group (the aldehyde). This ensures that the aldehyde gets the lowest possible number.

- Starting from the aldehyde:
- Carbon 1: CHO (aldehyde)
- Carbon 2: CH
- Carbon 3: CH
- Carbon 4: CH₃

Thus, the numbering is:
1. CHO
2. CH
3. CH
4. CH₃

### Step 4: Identify any double bonds
Now, we look for any double bonds in the carbon chain. In this case, there is a double bond between Carbon 2 and Carbon 3.

### Step 5: Assign locants for the double bond
Since the double bond is between Carbon 2 and Carbon 3, we will indicate this in the name. The position of the double bond is indicated by the number of the first carbon involved in the double bond.

### Step 6: Combine the names
Now we can combine the information:
- The longest chain has 4 carbons, which corresponds to the prefix "but".
- The double bond is at position 2, which we denote as "2".
- The aldehyde functional group is indicated by the suffix "al".

### Step 7: Finalize the IUPAC name
Putting it all together, we get:
- The compound is a butenal (due to the double bond) with an aldehyde group, leading to the final IUPAC name: **But-2-enal**.

### Final Answer:
The IUPAC name of the compound `CH₃-CH=CH-CHO` is **But-2-enal**.

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