Butyl is a hydrocarbon radical derived from one of the two isomers in butane. Taking away one of the hydrogen atoms in butane does this, but the type of butyl created depends on what butane isomer is used. There are four types of butyl-based combinations and, as isomers, they are all composed of the same elements in the same amount, but their skeletal arrangement is different. This is used to create many different commercial compounds, such as flavoring agents and bug repellants, and they are mostly created from petroleum.
The compound known as butyl does not exist in nature, but it is derived from butane. Butane has a chemical composition of four carbon atoms and 10 hydrogen atoms, and one of those hydrogen atoms must be removed to create the radical. There are two isomers of butane, called n-butane and iso-butane. Depending on which butane is used, one of four isomer radicals can be created.
If n-butane is used, then it will create either nbutyl or secbutyl. If iso-butane is used, then the chemist will get either isobutyl or tertbutyl. As isomers, all of these versions of butyl contain the same amount of atoms, but they have drastically different skeletons, which means they will connect differently with other compounds and atoms, yielding divergent results.
Butyls are often mixed with other elements to yield commercial products, and they are one of the most often used radicals in this market. Nbutyl is used to create artificial leather, perfumes and even insect repellants. Secbutyl is used mostly in fungi retardants. Isobutyl is used mostly in the medical field to treat hypoglycemia, or low blood sugar levels. Tertbutyl is found often with plastics, such as a light absorber for plastic wrap; it also is used to slow down polymerization needed for some plastics and rubbers.
Aside from being used in plastic, tertbutyl has a special property used frequently in chemistry. Tertbutyl is a bulky compound and, as such, can be used to balance kinetic energy in other compounds. For example, if a compound can yield two different products and the chemist wants to create the second one, which takes longer to activate because it needs more energy, then tertbutyl will be used. This will force the first product, which would naturally form, to require more energy and allow the second product to synthesize from the combination.
Butane is needed to form butyl, so the radical is formed from petroleum. There are several gases in petroleum, and butane is one of the lighter ones. This means butane is usually used, aside from making buytls, as a natural gas.