Butene, also known as butylene, is an
alkene
In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond.
Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic ...
with the formula . The word ''butene'' may refer to any of the individual compounds. They are colourless gases that are present in
crude oil as a minor constituent in quantities that are too small for viable extraction. Butene is therefore obtained by
catalytic cracking of long-chain hydrocarbons left during refining of crude oil. Cracking produces a mixture of products, and the butene is extracted from this by
fractional distillation.
Butene can be used as the
monomer
In chemistry, a monomer ( ; '' mono-'', "one" + '' -mer'', "part") is a molecule that can react together with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization.
Classification
...
for
polybutene Polybutene is an organic polymer made from a mixture of 1-butene, 2-butene, and isobutylene. Ethylene steam cracker C4s are also used as supplemental feed for polybutene. It is similar to polyisobutylene (PIB), which is produced from essentially p ...
, but this
polymer
A polymer (; Greek '' poly-'', "many" + '' -mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
is more expensive than alternatives with shorter carbon chains such as
polypropylene
Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene.
Polypropylene
belongs to the group of polyolefins a ...
. Polybutene is therefore used in more specialized applications. Butenes are more commonly used to make copolymer (mixed with another monomer such as ethylene).
Isomers
Among the molecules which have the
chemical formula
In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...
four
isomers
In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. ...
are
alkenes
In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond.
Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, a ...
. All four of these
hydrocarbons
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ...
have four
carbon
Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon ma ...
atom
Every atom is composed of a nucleus and one or more electrons bound to the nucleus. The nucleus is made of one or more protons and a number of neutrons. Only the most common variety of hydrogen has no neutrons.
Every solid, liquid, gas, a ...
s and one
double bond in their
molecule
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and b ...
s, but have different
chemical structure
A chemical structure determination includes a chemist's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target molecule or other solid. Molecular geometry refers to the spatial arrangement of ...
s. The
IUPAC
The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...
and common names, respectively, of these
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
s are:
In the chemical structures above, 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
Cyclobutane is a cycloalkane and organic compound with the formula (CH2)4. Cyclobutane is a colourless gas and commercially available as a liquefied gas. Derivatives of cyclobutane are called cyclobutanes. Cyclobutane itself is of no commerci ...
and
methylcyclopropane, but are not alkenes and do not fall under the name ''butene''. There are also cyclic alkenes with four carbon atoms overall such as
cyclobutene
Cyclobutene is a cycloalkene. It is of interest in research but currently has no practical applications. It is a colorless easily condensed gas. A modern synthesis involves the 2-step dehydration of cyclobutanol. The compound was first prepared ...
and two isomers of
methylcyclopropene, but they do not have the formula C
4H
8 and are not discussed here.
Properties
All four of these isomers are
gases at room
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied o ...
and
pressure
Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country a ...
, but can be liquefied by lowering the temperature or raising the pressure on them, in a manner similar to pressurised
butane. These gases are colourless, but do have distinct odours, and are highly
flammable. Although not naturally present in
petroleum
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...
in high percentages, they can be produced from
petrochemicals or by
catalytic cracking of
petroleum
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...
. Although they are stable compounds, the carbon-carbon double bonds make them more reactive than similar
alkanes
In organic chemistry, an alkane, or paraffin (a historical trivial name that also has other meanings), is an acyclic saturated hydrocarbon. In other words, an alkane consists of hydrogen and carbon atoms arranged in a tree structure in ...
, which are more inert compounds in various ways.
Because of the double bonds, these 4-carbon alkenes can act as
monomers in the formation of
polymers
A polymer (; Greek '' poly-'', "many" + '' -mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
, as well as having other uses as
petrochemical
Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewabl ...
intermediates. They are used to slay in the production of
synthetic rubber. But-1-ene is a linear or normal
alpha-olefin and isobutylene is a branched alpha-olefin. In a rather low percentage, but-1-ene is used as one of the comonomers, along with other alpha-olefins, in the production of
high-density polyethylene
High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a thermoplastic polymer produced from the monomer ethylene. It is sometimes called "alkathene" or "polythene" when used for HDPE pipes. With a high strength-to-density rat ...
and
linear low-density polyethylene
Linear low-density polyethylene (LLDPE) is a substantially linear polymer ( polyethylene), with significant numbers of short branches, commonly made by copolymerization of ethylene with longer-chain olefins. Linear low-density polyethylene differ ...
.
Butyl rubber
Butyl rubber, sometimes just called "butyl", is a synthetic rubber, a copolymer of isobutylene with isoprene. The abbreviation IIR stands for isobutylene isoprene rubber. Polyisobutylene, also known as "PIB" or polyisobutene, (C4H8)n, is the ...
is made by cationic
polymerisation 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
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic c ...
.
See also
*
1,3-Butadiene
1,3-Butadiene () is the organic compound with the formula (CH2=CH)2. It is a colorless gas that is easily condensed to a liquid. It is important industrially as a precursor to synthetic rubber. The molecule can be viewed as the union of two v ...
*
Alkene
In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond.
Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic ...
References
External links
MSDS for isobutylene
{{Authority control
Alkenes
Monomers
GABAA receptor positive allosteric modulators