The `IUPAC` name of the compound `CH_(3)CH=CHC-=CH` is

Options

A. Pent - 3 - en - 1 - yne
B. Pent - 2 - en - 4 - yne
C. Pent - 1 - yn - 3 - ene
D. Pent - 4 - yn - 2 – ene

Answer

To determine the IUPAC name of the compound \( CH_3CH=CHC \equiv CH \), we will follow these steps:

### Step 1: Identify the longest carbon chain
The first step in naming an organic compound is to identify the longest continuous carbon chain. In this case, the longest chain consists of 5 carbon atoms.

### Step 2: Number the carbon chain
Next, we need to number the carbon chain. According to IUPAC rules, we should give the lowest possible numbers to the multiple bonds (triple and double bonds).

Starting from the right side:
- Carbon 1: \( CH \) (triple bond)
- Carbon 2: \( C \)
- Carbon 3: \( CH \) (double bond)
- Carbon 4: \( CH_2 \)
- Carbon 5: \( CH_3 \)

So, the numbering is as follows:
1. \( C_1 \) (triple bond)
2. \( C_2 \)
3. \( C_3 \) (double bond)
4. \( C_4 \)
5. \( C_5 \)

### Step 3: Identify the types of bonds
From the numbering:
- There is a triple bond between carbon 1 and carbon 2.
- There is a double bond between carbon 3 and carbon 4.

### Step 4: Name the compound
Now we can construct the name based on the longest chain and the positions of the double and triple bonds:
- The longest chain has 5 carbons, so it is a "pent" compound.
- The double bond is at position 3, so we denote it as "3-en".
- The triple bond is at position 1, so we denote it as "1-yne".

### Step 5: Combine the names
Combining these, we get the IUPAC name as:
\[ \text{Pent-3-ene-1-yne} \]

### Final Answer:
The IUPAC name of the compound \( CH_3CH=CHC \equiv CH \) is **Pent-3-ene-1-yne**.

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