Isomers of butylene
There are four
isomers of
alkenes which have the
chemical formula 48. All four of these
hydrocarbons have four
carbon atoms and one
double bond in their
molecules, but have different
chemical structures. The
IUPAC and common names, respectively, of these
chemical compounds are:
| IUPAC name | common name | | 1-butene | α-butylene |
| cis-2-butene | cis-β-butylene |
| trans-2-butene | trans-β-butylene |
| methylpropene | isobutylene |
|
The chemical structures are shown at right. The small blue numbers in the structure images are the numbering of the atoms in the main backbone chain of the molecules. Other organic compounds have the formula C
4H
8, namely
cyclobutane and
methylcyclopropane, but are not alkenes and are not discussed here. There are also four-carbon cyclic alkenes such as
cyclobutene and
methylcyclopropene, but they do not have the formula C
4H
8 and are not discussed here.
All four of these isomers are at room
temperature and
pressure, but can be liquified by lowering the temperature or raising the pressure on them, in a manner similar to pressurized
butane. These gases are colorless, but do have distinct odors, and are highly
flammable. Although not naturally present in
petroleum in high percentages, they can be produced from
petrochemicals or by
catalytic cracking of
petroleum. Although they are stable compounds, the carbon-carbon double bonds make them more reactive than similar
alkanes, which are more inert compounds in many ways.
Because of the double bonds, these 4-carbon alkenes can act as
monomers in the formation of
polymers, as well as having other uses as
petrochemical intermediates. They are used in the production of
synthetic rubber. 1-Butene is a linear or normal
alpha-olefin and isobutylene is a branched alpha-olefin. In a rather low percentage, 1-butene is used as one of the comonomers, along with other alpha-olefins, in the production of
high density polyethylene and
linear low density polyethylene.
Butyl rubber is made by cationic
polymerization of isobutylene with about 2 - 7%
isoprene. Isobutylene is also used for the production of methyl
tert-butyl ether (
MTBE) and
isooctane, both of which improve the combustion of
gasoline.
*
MSDS for isobutylene
