Butino: Structure, Properties And Uses

The butyne is a chemical compound belongs to the group of alkynes, mainly characterized by having in its structure to the least one triple bond between two carbon atoms.

When it comes to establishing rules for the naming of alkynes, the IUPAC (International Union of Pure and Applied Chemistry) has established that the same rules are used as for alkenes.

Synthesis of 1-butyne from a dihalogenide. By Marcosm21 [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], from Wikimedia Commons

The fundamental difference between the nomenclature of both types of substances is that the suffix -no changes to -no when it comes to compounds that have triple bonds in their structure.

On the other hand, butyne is made up solely of carbon and hydrogen, and occurs in two forms: 1-butyne, which is found in the gas phase under standard pressure and temperature conditions (1 atm, 25 ° C); and 2-butyne, which is a liquid phase species produced by chemical synthesis.

Article index

  • one

    Chemical structure

    • 1.1

      1-butyne

    • 1.2

      2-butyne

  • two

    Properties (edit)

  • 3

    Applications

  • 4

    References

Chemical structure

In the molecule known as butyne, the phenomenon of positional structural isomerism occurs, which consists of the presence of the same functional groups in both compounds, but each of these are found in a different place in the chain.

In this case, both forms of butyne have an identical molecular formula; however, in 1-butyne the triple bond is located at carbon number one, while in 2-butyne it is located at number two. This converts them to positional isomers.

Due to the location of the triple bond in one of the terminals of the 1-butyne structure, it is considered a terminal alkyne, while the intermediate position of the triple bond in the 2-butyne structure gives it the classification of internal alkyne .

Thus, the bond can only be between the first and second carbon (1-butyne) or between the second and third carbon (2-butyne). This is due to the nomenclature applied, where the lowest possible numbering will always be given to the position of the triple bond.

1-butyne

The compound called 1-butyne is also known as ethylacetylene, due to its structure and the way its four carbon atoms are arranged and bonded. However, when we speak of butyne, we refer only to this chemical species.

In this molecule, the triple bond is at a terminal carbon, which allows the availability of hydrogen atoms that give it great reactivity.

By Jynto and Ben Mills [Public domain], via Wikimedia Commons

This rigid bond and stronger than a single or double bond between the carbon atoms provides a stable configuration of linear geometry to 1-butyne.

On the other hand, this gaseous substance is quite flammable, so in the presence of heat it can easily cause fires or explosions and has great reactivity in the presence of air or water.

2-butyne

As internal alkynes exhibit greater stability than terminal alkynes, they allow the transformation of 1-butyne into 2-butyne.

This isomerization can occur by heating 1-butyne in the presence of a base (such as NaOH, KOH, NaOCH3 …) or through the rearrangement of 1-butyne in a solution of potassium hydroxide (KOH) in ethanol (C 2 H 6 O).

By Kemikungen [Public domain], from Wikimedia Commons

In the same way, the chemical substance known as 2-butyne is also called dimethylacetylene (or crotonylene), presenting itself as a liquid and volatile species that originates artificially.

In 2-butyne, the triple bond is found in the middle of the molecule, giving it greater stability than its isomer.

Furthermore, this colorless compound has a lower density than water, although it is considered insoluble in it and has high flammability.

Properties (edit)

-The structural formula of butyne (regardless of which isomer is referred to) is C 4 H 6 , which has a linear structure.

-One of the chemical reactions that the butyne molecule undergoes is isomerization, in which a rearrangement and migration of the triple bond occurs within the molecule.

-Butyne-1 is in the gaseous phase, has a very high flammability and a higher density than air.

-This substance is also quite reactive, and in the presence of heat it can cause violent explosions.

-In addition, when this colorless gas undergoes an incomplete combustion reaction, it can cause carbon monoxide (CO)

-When both isomers are exposed to high temperatures, they can undergo explosive polymerization reactions.

-The 2-butyne is in the liquid phase, although it is also considered quite flammable under standard conditions of pressure and temperature.

-These substances can undergo violent reactions when they are in the presence of strong oxidizing substances.

-In the same way, when they are in the presence of reducing species, exothermic reactions occur with a consequent release of hydrogen gas.

-When in contact with certain catalysts (such as some acid substances) or initiating species, exothermic polymerization reactions may occur.

Applications

Because they have some different properties, the two isomers can have different uses and applications, as shown below:

In the first place, very often one of the applications of 1-butyne is its use as an intermediate stage in the production process of other substances of an organic nature of synthetic origin.

On the other hand, this chemical species is used in the rubber manufacturing industry and derived compounds; as for example, when you want to obtain benzol.

In a similar way, it is used in the manufacturing process of a great variety of plastic products, as well as in the elaboration of many polyethylene substances considered of high density.

Also 1-butyne is frequently used as a component for the cutting and welding processes of some metal alloys, including steel (alloy of iron and carbon).

In another sense, the 2-butyne isomer is used in combination with another alkyne called propyne in the synthesis of some substances known as alkylated hydroquinones, when the total synthesis process of α-tocopherol (vitamin E) is carried out.

References

  1. Wikipedia. (sf). Butyne. Recovered from en.wikipedia.org
  2. Yoder, CH, Leber PA and Thomsen, MW (2010). The Bridge to Organic Chemistry: Concepts and Nomenclature. Recovered from books.google.co.ve
  3. Study.com. (sf). Butyne: Structural Formula & Isomers. Obtained from study.
  4. PubChem. (sf). 1-Butyne. Recovered from pubchem.ncbi.nlm.nih.gov
  5. PubChem. (sf). 2-Butyne. Retrieved from pubchem.ncbi.nlm.nih.gov

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