Butene, also known as butylene,'s an alkene with the formula C4H8. It's a colourless gas that's present in crude oil as a minor constituent in quantities that're too small for viable extraction. It's therefore obtained by catalytic cracking of long chain hydrocarbons left during refining of crude oil. Cracking produces a mixture of products and the butene's extracted form this by fractional distillation. Butene can be used as the monomer for polybutene but this polymer's more expensive than alt… (More on Butylene)