(1) Turpentine and numerous other olefinic compounds, phosphorus and certain metals like Zn and Pb can absorb oxygen from the air in presence of water. The water is oxidised to hydrogen peroxide. This phenomenon of formation of H2O2 by the oxidation of H2O is known as autoxidation. The substance such as turpentine or phosphorus or lead which can activate the oxygen is called activator. The activator is supposed to first combine with oxygen to form an addition compound, which acts as an autoxidator and reacts with water or some other acceptor so as to oxidise the latter. For example;
(2) The turpentine or other unsaturated compounds which act as activators are supposed to take up oxygen molecule at the double bond position to form unstable peroxide called moloxide, which then gives up the oxygen to water molecule or any other acceptor.
The evolution of iodine from KI solution in presence of turpentine can be confirmed with starch solution which turns blue.
(3) The concept of autoxidation help to explain the phenomenon of induced oxidation. solution is oxidised by air but solution is not oxidised by air. If a mixture of both is taken, it is observed both are oxidised. This is induced oxidation.