Give the reactions of ether compounds involving the cleavage of the $C-O$ bond with examples.

(N/A) Reactivity of ethers with $HX$:
$(i)$ Ethers are the least reactive among all functional groups.
$(ii)$ Ether compounds react with excess hydrogen halides $(HX)$ under vigorous conditions to produce alcohols and alkyl halides.
$R-O-R + HX \xrightarrow{\Delta} RX + ROH$
$(iii)$ The order of reactivity of hydrogen halides $(HX)$ with ethers is $HI > HBr > HCl$.
$(iv)$ Ethers react with concentrated $HI$ or $HBr$ at high temperatures to cleave the $C-O$ bond,forming alcohol and alkyl halide.
$(b)$ Ease of $C-O$ bond cleavage in ethers:
$(i)$ In dialkyl ethers with identical alkyl groups,cleavage of the $C-O$ bond by $HX$ yields identical products.
$(ii)$ In alkyl aryl ethers $(R-O-Ar)$,the alkyl-oxygen $(R-O)$ bond is cleaved,yielding $RX$ and $ArOH$.
The $Ar-O$ bond is stronger and more stable than the $R-O$ bond due to partial double bond character. The weaker $R-O$ bond breaks,and the nucleophile $X^-$ attacks the alkyl group to form $RX$,while $H^+$ adds to the phenoxide ion to form $ArOH$ (phenol).