2-Butyne (dimethylacetylene, crotonylene or but-2-yne) is an
alkyne
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Acetylene
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Propyne
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1-Butyne
In organic chemistry, an alkyne is an unsaturated hydrocarbon containing at least one carbon—carbon triple bond. The simplest acyclic alkynes with only one triple bond and n ...
with
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, ...
CH
3C≡CCH
3. Produced artificially, it is a colorless, volatile, pungent liquid at
standard temperature and pressure
Standard temperature and pressure (STP) are standard sets of conditions for experimental measurements to be established to allow comparisons to be made between different sets of data. The most used standards are those of the International Union o ...
.
2-Butyne is of interest to physical chemists because of its very low torsional barrier and the problem of determining that barrier using high-resolution infrared spectroscopy. Analysis of its spectrum
leads to a determination that the torsional barrier is only 6 cm
−1 (1.2 J or 72 J mol
−1). However, it has not been determined whether the equilibrium structure is eclipsed (D
3h) or staggered (D
3d). Symmetry analysis using the Molecular Symmetry Group
G
36 shows that one would need to analyse its high resolution rotation-vibration Raman spectrum to determine its equilibrium structure.
2-Butyne (''dimethylethyne'') forms with
5-decyne (''dibutylethyne''),
4-octyne (''dipropylethyne'') and
3-hexyne (''diethylethyne'') a group of symmetric alkynes.
Synthesis
2-Butyne can be synthesized by the
rearrangement reaction
In organic chemistry, a rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. Often a substituent moves from one atom to another ...
of
ethylacetylene
1-Butyne is an organic compound with the chemical formula HC2CH2CH3. It is a colorless combustable gas. 1-Butyne participates in reactions typical for terminal alkynes, such as alkyne metathesis, hydrogenation, condensation with formaldehyde. Base ...
in a solution of
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an Alcohol (chemistry), alcohol with the chemical formula . Its formula can be also written as or (an ethyl ...
ic
potassium hydroxide
Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash.
Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exp ...
.
Applications
2-Butyne, along with
propyne
Propyne (methylacetylene) is an alkyne with the chemical formula . It is a component of MAPD gas—along with its isomer propadiene (allene), which was commonly used in gas welding. Unlike acetylene, propyne can be safely condensed.Peter Päs ...
, is used to synthesize
alkylated
Alkylation is the transfer of an alkyl group from one molecule to another. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene (or their equivalents). Alkylating agents are reagents for effecting al ...
hydroquinone
Hydroquinone, also known as benzene-1,4-diol or quinol, is an aromatic organic compound that is a type of phenol, a derivative of benzene, having the chemical formula C6H4(OH)2. It has two hydroxyl groups bonded to a benzene ring in a ''para'' ...
s in the
total synthesis
Total synthesis is the complete chemical synthesis of a complex molecule, often a natural product, from simple, commercially-available precursors. It usually refers to a process not involving the aid of biological processes, which distinguishes ...
of
Vitamin E
Vitamin E is a group of eight fat soluble compounds that include four tocopherols and four tocotrienols. Vitamin E deficiency, which is rare and usually due to an underlying problem with digesting dietary fat rather than from a diet low in vitami ...
.
See also
*
1-Butyne
1-Butyne is an organic compound with the chemical formula HC2CH2CH3. It is a colorless combustable gas. 1-Butyne participates in reactions typical for terminal alkynes, such as alkyne metathesis, hydrogenation, condensation with formaldehyde. Base ...
, a position isomer
References
Alkynes
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