Tertiary alcohols do not undergo oxidation in the presence of an oxidizing agent. This is because the carbon atom that contains the alcohol functional group is devoid of any hydrogen atoms, which are necessary in the oxidation mechanism of alcohols.
There are three types of alcohols, which are classified based on the number of hydrogen atoms bonded to the carbon atom that is bonded to the oxygen atom in the functional group of an alcohol. Primary alcohols have two hydrogen atoms, secondary alcohols have one hydrogen atom and tertiary alcohols have no hydrogen atoms bonded to the carbon that is bonded to the oxygen atom.
Oxidation of alcohols can only take place in the presence of an oxidizing agent, such as acidified potassium dichromate, which in turn is reduced during the process. The dichromate (IV) ions are reduced to chromium (III) ions through the addition of electrons. This process involves the removal of the hydrogen atoms bonded to the oxygen itself in the alcohol?s functional group, as well as from the carbon containing the alcohol group (known as the carbinol carbon).
Since primary alcohols contain two hydrogen atoms on the carbinol carbon, they can be oxidized to aldehydes and then to carboxylic acids. Secondary alcohols can be oxidized only once to ketones, since they contain only one hydrogen atom on the carbinol carbon. Tertiary alcohols are resistant to oxidation, since their carbinol carbons have no hydrogen atoms that can take part in the transfer of electrons to the dichromate ions.