Question

Preparation of ethers by acid dehydration of secondary and tertiary alcohol is not a suitable method

Answer 1

in presence of 140°c
CH3-CH2-Cl + H2SO4(conc.) ->
CH3-CH2-O-CH2-CH3(diethyl ether)
But tertiary alcohol in presence of conc. H2SO4 is formed 2-methyl propene(alkene).
In this reason tertiary alcohol is not a suitable method.
But tert butyl alcohol is suitable method of preparations of ether. this is exception.