Question

Why ethers only undergo cleavage with strong acids and not with weaker acids?

Answer 1

Basically because the `C-O` bond is strong........

Explanation:

As far as anyone knows the oxygen, as the most basic site of the ether, `R-O-R`, is protonated by an acid, `HX`, to give `R-O^(+)H-R` and `X^(-)`. This weakens the `C-O` bond such that it may cleaved by (say) a water molecule to give `2xxROH`.

The stronger the acid, `HX`, the weaker the `H-X` bond, and the more likely it is to cause hydrolysis of the ether moiety.