What is the IUPAC nomenclature of isoprene monomer present in natural rubber?

Options

A. 2 - methyl -1, 3 - butadiene
B. 1, 3- Hexadiene
C. 2, 3 - Dimethyl -1, 3 - butadiene
D. 2 - Methyl-1, 3 - pentadiene

Answer

To determine the IUPAC nomenclature of the isoprene monomer present in natural rubber, we will follow these steps:

### Step 1: Identify the Structure of Isoprene
The chemical structure of isoprene is:
\[ \text{CH}_2=\text{C}(\text{CH}_3)-\text{CH}=\text{CH}_2 \]

### Step 2: Count the Carbon Atoms
In the isoprene structure, we can see that there are 5 carbon atoms.

### Step 3: Identify the Functional Groups
Isoprene contains two double bonds (alkenes) in its structure.

### Step 4: Number the Carbon Atoms
We will number the carbon atoms starting from one end of the chain. The numbering will be as follows:
1. CH2 (C1)
2. C (C2, which has a methyl group attached)
3. CH (C3)
4. CH2 (C4)
5. CH (C5)

### Step 5: Determine the Position of Double Bonds
The double bonds are located between:
- C1 and C2
- C3 and C4

### Step 6: Write the IUPAC Name
Based on the numbering and the presence of double bonds, the IUPAC name of isoprene is:
**2-methyl-1,3-butadiene**

### Final Answer
The IUPAC nomenclature of the isoprene monomer present in natural rubber is **2-methyl-1,3-butadiene**.

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