Butene, also known as butylene, is an alkene with the formula C4H8. It is a colourless gas that's present in crude oil as a minor constituent so is mostly obtained by cracking of long chain hydrocarbons left during refining of crude oil.The polymer produced from butene is more expensive than alternatives with shorter carbon chains such as polypropylene but is commonly used as a co-polymer (mixed with another polymer, either during or after reaction), such as in hot-melt adhesives. Isomers Among… (More on Butylene)