Order of reactivity of hydrogen halides towards ethers is

Options

A. `HCl gt HBr gt HI`
B. `HI gt HBr gt HCl`
C. `HBr gt HI gt HCl`
D. `HBr gt HCl gt HI`

Answer

To determine the order of reactivity of hydrogen halides (HX) towards ethers, we need to analyze the bond strengths and the acidity of the hydrogen halides. The hydrogen halides in question are HCl, HBr, and HI.

### Step-by-Step Solution:

1. **Understanding Ethers**: Ethers have the general structure R-O-R', where R and R' are alkyl groups. When ethers react with hydrogen halides, they can undergo cleavage to form alcohols and alkyl halides.

2. **Reaction Mechanism**: When an ether reacts with an excess of a hydrogen halide (HX), the ether bond (C-O) breaks. This leads to the formation of an alcohol and an alkyl halide. The reaction can be represented as:
\[ R-O-R' + HX \rightarrow R-OH + R'X \]
where X is a halide ion (Cl, Br, or I).

3. **Bond Strength and Acidity**: The reactivity of the hydrogen halides towards ethers is influenced by the bond strength of the H-X bond. The weaker the bond, the easier it is for the bond to break, leading to higher reactivity.

4. **Comparing HCl, HBr, and HI**:
- **HI**: Hydroiodic acid has the weakest H-I bond due to its larger atomic size and lower bond enthalpy, making it the most reactive towards ethers.
- **HBr**: Hydrobromic acid has a stronger H-Br bond than HI but weaker than HCl, making it less reactive than HI but more reactive than HCl.
- **HCl**: Hydrochloric acid has the strongest H-Cl bond among the three, making it the least reactive towards ethers.

5. **Order of Reactivity**: Based on the bond strengths and acidity, the order of reactivity of hydrogen halides towards ethers is:
\[ HI > HBr > HCl \]

### Final Answer:
The order of reactivity of hydrogen halides towards ethers is:
**HI > HBr > HCl**