Oxidizers can undergo spontaneous combustion by three different means. First, there is slow oxidization. This occurs when oxygen comes in contact with a materials that has double bonds (also known as pi bonds), such as animal or vegetable oils and alkenes.Animal and vegetable oils are actually large esters, with the exception of turpentine, which is a pure hydrocarbon compound. The problem is the same, however; the double bonds in turpentine can be attacked by oxygen from the air and can undergo spontaneous ignition. The structure and molecular formula for turpentine are show in Figure 7.5; notice the double bonds.