Electrophilic subsitution reaction in phenol take place at :

Options

A. Ortho and para positions
B. Meta - position
C. Ortho - position
D. Para - position

Answer

To determine where electrophilic substitution reactions take place in phenol, we can follow these steps:

### Step 1: Understand the Structure of Phenol
Phenol consists of a benzene ring with a hydroxyl group (-OH) attached to it. The structure can be represented as follows:

```
OH
|
C6H5
```

### Step 2: Analyze the Resonance Effect
The hydroxyl group has two lone pairs of electrons, which can participate in resonance with the benzene ring. This means that the electron density in the ring can be affected by the presence of the -OH group.

### Step 3: Draw Resonance Structures
When considering resonance, we can draw several structures to visualize how the electron density shifts. The lone pairs on the oxygen can donate electrons into the benzene ring, increasing the electron density at certain positions:

1. **First Resonance Structure**: The lone pair on the oxygen forms a bond with the adjacent carbon, creating a double bond between that carbon and the next carbon in the ring. This shifts the double bond to another carbon in the ring.

2. **Second Resonance Structure**: The process can be repeated, showing that the electron density can be delocalized around the ring.

### Step 4: Identify Electron-Rich Positions
From the resonance structures, we can see that the ortho (adjacent to the -OH group) and para (opposite the -OH group) positions have increased electron density due to resonance. The meta position (one carbon away from the -OH group) does not benefit from this resonance effect as much.

### Step 5: Conclusion on Electrophilic Substitution
Electrophiles are electron-deficient species that seek areas of high electron density to react. Since the ortho and para positions are electron-rich due to the resonance effect from the hydroxyl group, electrophilic substitution reactions will preferentially occur at these positions.

### Final Answer
Electrophilic substitution reactions in phenol take place at the ortho and para positions.

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