CHEMICALS FROM ISOBUTYLENE

   Isobutylene (CH₂=C(CH₃)₂) is a reactive C₄ olefin. Until recently, almost all isobutylene was obtained as a by-product with other C₄ hydrocarbons from different cracking processes. It was mainly used to produce alkylates for the gasoline pool. A small portion was used to produce chemicals such as isoprene and diisobutylene. However, increasing demand for oxygenates from isobutylene has called for other sources. n-Butane is currently used as a precursor for isobutylene. The first step is to isomerize n-butane to isobutane, then dehydrogenate it to isobutylene.

   This serves the dual purpose of using excess n-butane (that must be removed from gasolines due to new rules governing gasoline vapor pressure) and producing the desired isobutylene. Currently, the major use of iosbutylene is to produce methyl-ter-butyl ether. The following section reviews the chemistry of isobutylene and its important chemicals.