The ether that undergoes electrophilic substitution reactions is

Options

A. `CH_3OC_2H_5`
B. `C_6H_5OCH_3`
C. `CH_OCH_3`
D. `C_2H_OC_2H_3`

Explanation

To determine which ether undergoes electrophilic substitution reactions, we need to analyze the given options based on the structure of the ethers and the nature of their substituents.

### Step-by-Step Solution:

1. **Understand the Types of Ethers**:
- Ethers can be classified into two categories: alkyl-alkyl ethers and alkyl-aryl ethers.
- Alkyl-aryl ethers contain an aryl group (like a benzene ring) attached to an alkyl group, while alkyl-alkyl ethers consist of two alkyl groups.

2. **Evaluate Each Option**:
- **Option A: CH3OCH2H5 (Ethyl methyl ether)**:
- This is an alkyl-alkyl ether (both groups are alkyl). Alkyl-alkyl ethers do not undergo electrophilic substitution reactions.

- **Option B: C6H5OCH3 (Anisole)**:
- This is an alkyl-aryl ether (the presence of the benzene ring, C6H5, makes it an aryl group). Alkyl-aryl ethers can undergo electrophilic substitution reactions due to the electron-rich nature of the benzene ring.

- **Option C: CH3OCH3 (Dimethyl ether)**:
- This is also an alkyl-alkyl ether. Like option A, it does not undergo electrophilic substitution reactions.

- **Option D: C2H5OCH2H5 (Diethyl ether)**:
- This is another alkyl-alkyl ether. Similar to options A and C, it does not undergo electrophilic substitution reactions.

3. **Conclusion**:
- Based on the analysis, the only ether that can undergo electrophilic substitution reactions is **Option B: C6H5OCH3 (Anisole)**.

### Final Answer:
The ether that undergoes electrophilic substitution reactions is **C6H5OCH3 (Anisole)**.

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