When the vapours of tertiary butyl alcohol are passed through heated copper of 573K
when the vapours of an alcohol are passed over copper catalyst heated at 573K. it undergoes dehydrogenation (loss of hydrogen or oxidation). The product formed depends on the alcohol and hence this reaction is also used to distinguish the three classes of alcohols.
Tertiary alcohol when reacted with copper catalyst at 573K are not dehydrogenated but undergoes dehydration to give the corresponding alkene.