Vinylacetylene
Encyclopedia
Vinylacetylene is the organic compound
with the formula C4H4. The colourless gas was once used in the polymer industry. It is composed of both alkyne
and alkene
groups.
Vinylacetylene is extremely dangerous because in high enough concentrations (typically > 30 mole percent, but pressure dependent) it can auto-detonate (explode without air being present) especially at elevated pressures, such as those seen in chemical plants processing C4 hydrocarbons. An example of such an explosion occurred at a Union Carbide plant in Texas City in 1969.
of the related quaternary ammonium salt:
It is usually synthesized by dehydrohalogenation
of 1,3-dichloro-2-butene. It also arises via the dimerization of acetylene
or dehydrgenation of 1,3-butadiene
.
(2-chloro-1,3-butadiene), an industrially important monomer
, was produced via the intermediacy of vinyl acetylene. In this process, acetylene
is dimerized to give vinyl acetylene, which is then combined with hydrogen chloride
to give 4-chloro-1,2-butadiene, which, in the presence of cuprous chloride, rearranges to 2-chloro-1,3-butadiene.
Organic compound
An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...
with the formula C4H4. The colourless gas was once used in the polymer industry. It is composed of both alkyne
Alkyne
Alkynes are hydrocarbons that have a triple bond between two carbon atoms, with the formula CnH2n-2. Alkynes are traditionally known as acetylenes, although the name acetylene also refers specifically to C2H2, known formally as ethyne using IUPAC nomenclature...
and alkene
Alkene
In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...
groups.
Vinylacetylene is extremely dangerous because in high enough concentrations (typically > 30 mole percent, but pressure dependent) it can auto-detonate (explode without air being present) especially at elevated pressures, such as those seen in chemical plants processing C4 hydrocarbons. An example of such an explosion occurred at a Union Carbide plant in Texas City in 1969.
Synthesis
Vinylacetylene was first prepared by Hofmann eliminationHofmann elimination
Hofmann elimination is a process where an amine is reacted to create a tertiary amine and an alkene by treatment with excess methyl iodide followed by treatment with silver oxide, water, and heat.After the first step, a quaternary ammonium iodide salt is created...
of the related quaternary ammonium salt:
- [(CH3)3NCH2CH=CHCH2N(CH3)3]I2 → 2 [(CH3)3NH]I + HC≡C-CH=CH2
It is usually synthesized by dehydrohalogenation
Dehydrohalogenation
Dehydrohalogenation is an organic reaction from which an alkene is obtained from an alkyl halide . It is also called a β-Elimination reaction and is a type of elimination reaction....
of 1,3-dichloro-2-butene. It also arises via the dimerization of acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...
or dehydrgenation of 1,3-butadiene
1,3-Butadiene
1,3-Butadiene is a simple conjugated diene with the formula C4H6. It is an important industrial chemical used as a monomer in the production of synthetic rubber. When the word butadiene is used, most of the time it refers to 1,3-butadiene....
.
Application
At one time, chloropreneChloroprene
Chloroprene is the common name for the organic compound 2-chlorobuta-1,3-diene, which has the formula CH2=CCl-CH=CH2. This colorless liquid is the monomer for the production of the polymer polychloroprene, a type of synthetic rubber...
(2-chloro-1,3-butadiene), an industrially important monomer
Monomer
A monomer is an atom or a small molecule that may bind chemically to other monomers to form a polymer; the term "monomeric protein" may also be used to describe one of the proteins making up a multiprotein complex...
, was produced via the intermediacy of vinyl acetylene. In this process, acetylene
Acetylene
Acetylene is the chemical compound with the formula C2H2. It is a hydrocarbon and the simplest alkyne. This colorless gas is widely used as a fuel and a chemical building block. It is unstable in pure form and thus is usually handled as a solution.As an alkyne, acetylene is unsaturated because...
is dimerized to give vinyl acetylene, which is then combined with hydrogen chloride
Hydrogen chloride
The compound hydrogen chloride has the formula HCl. At room temperature, it is a colorless gas, which forms white fumes of hydrochloric acid upon contact with atmospheric humidity. Hydrogen chloride gas and hydrochloric acid are important in technology and industry...
to give 4-chloro-1,2-butadiene, which, in the presence of cuprous chloride, rearranges to 2-chloro-1,3-butadiene.