Explain why ArOR ethers are cleaved to give RI and ArOH rather
than Arl and ROH.

Answer

To explain why ArOR ethers are cleaved to give RI (alkyl halide) and ArOH (phenol) rather than ArI (aryl halide) and ROH (alcohol), we can break down the explanation into several steps:

### Step-by-Step Solution:

1. **Understanding the Structure of ArOR Ethers**:
- ArOR ethers consist of an aryl group (Ar) bonded to an alkoxy group (R-O). For example, anisole (C6H5-O-CH3) is a common aryl ether.

2. **Protonation of the Ether**:
- When an aryl ether is treated with a strong acid (like HI), the ether oxygen can be protonated, forming an oxonium ion. For anisole, this would yield a methyl-phenyl-oxonium ion (C6H5-O^+-CH3).

3. **Bond Strength Consideration**:
- The bond between the oxygen and the aryl group (O-Ar) is stronger than the bond between the oxygen and the alkyl group (O-R). This is due to resonance stabilization in the aryl ether, where the lone pair of electrons on the oxygen can delocalize into the aromatic ring.

4. **Nucleophilic Attack**:
- When the iodide ion (I^-) attacks the oxonium ion, it preferentially breaks the weaker O-R bond (O-CH3) rather than the stronger O-Ar bond (O-C6H5). This results in the formation of methyl iodide (RI) and phenol (ArOH).

5. **Inability to Form Aryl Halides**:
- The phenol formed does not undergo further nucleophilic substitution to form aryl halides (ArI) because the sp2 hybridized carbon in phenol is less reactive towards nucleophiles due to resonance stabilization. Therefore, the phenolic compound remains intact.

6. **Conclusion**:
- The cleavage of ArOR ethers leads to the formation of RI and ArOH rather than ArI and ROH due to the relative bond strengths and the stability of the resulting products.