The intermediate formed in the electrophilic addition of HBr to propene is a

Options

A. Carbocation
B. Carbanion
C. Carbene
D. Free radical

Answer

To determine the intermediate formed in the electrophilic addition of HBr to propene, we can follow these steps:

### Step 1: Identify the Structure of Propene
Propene is an alkene with the molecular formula C3H6. Its structure can be represented as:
\[ \text{CH}_3\text{CH}=\text{CH}_2 \]

### Step 2: Understand Electrophilic Addition
Electrophilic addition involves the reaction of an electrophile (in this case, HBr) with a nucleophile (the double bond in propene). The double bond in propene is nucleophilic due to the high electron density.

### Step 3: Analyze the Electrophile
HBr can be polarized due to the difference in electronegativity between hydrogen and bromine. This results in:
- A partial positive charge (δ+) on hydrogen
- A partial negative charge (δ-) on bromine

### Step 4: Protonation of Propene
When HBr approaches the double bond in propene, the double bond acts as a nucleophile and attacks the δ+ hydrogen atom. This leads to the formation of a carbocation intermediate. The reaction can be illustrated as follows:
\[ \text{CH}_3\text{CH}=\text{CH}_2 + \text{H}^+ \rightarrow \text{CH}_3\text{CH}^+\text{CH}_2 \]

### Step 5: Formation of the Carbocation
The addition of the proton (H+) to the double bond results in the formation of a carbocation:
\[ \text{CH}_3\text{CH}^+\text{CH}_2 \]
This carbocation is a positively charged species and is the intermediate formed during the reaction.

### Step 6: Attack by Bromide Ion
After the formation of the carbocation, the bromide ion (Br-) can now attack the positively charged carbon atom:
\[ \text{CH}_3\text{CH}^+\text{CH}_2 + \text{Br}^- \rightarrow \text{CH}_3\text{CHBr}\text{CH}_2 \]

### Conclusion
The intermediate formed in the electrophilic addition of HBr to propene is a **carbocation**.

### Final Answer
The intermediate formed in the electrophilic addition of HBr to propene is a **carbocation**.

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