Question

Compare the condensed structural formulas of 1-butyne and 2-butyne.

Short answer

1-butyne: CH≡C-CH₂-CH₃; 2-butyne: CH₃-C≡C-CH₃.

Step-by-step solution

Understand the structure of 1-butyne

1-butyne is an alkyne with the triple bond between the first and second carbon atoms of a four-carbon chain. Its condensed structural formula is CH≡C-CH₂-CH₃.

Understand the structure of 2-butyne

2-butyne is an alkyne with the triple bond between the second and third carbon atoms of a four-carbon chain. Its condensed structural formula is CH₃-C≡C-CH₃.

Compare the two condensed structural formulas

1-butyne has the condensed formula CH≡C-CH₂-CH₃, whereas 2-butyne has the formula CH₃-C≡C-CH₃. The position of the triple bond defines the difference between the two compounds.

Key concepts

1-butyne

1-Butyne is an example of an alkyne, a type of hydrocarbon characterized by having at least one carbon-carbon triple bond. Specifically, in 1-butyne, this triple bond is located between the first and second carbon atoms in a four-carbon chain. The condensed structural formula of 1-butyne is written as CH≡C-CH₂-CH₃.
The '1-' prefix indicates the position of the triple bond, making it clear that it starts at the first carbon atom.
This structure tells you that the other two carbon atoms are connected by single bonds and the remaining bonds are filled with hydrogen atoms.

2-butyne

2-Butyne is another type of alkyne but differs from 1-butyne in the position of the triple bond. For 2-butyne, the triple bond is located between the second and third carbon atoms in a four-carbon chain. The condensed structural formula of 2-butyne is written as CH₃-C≡C-CH₃.
The '2-' prefix indicates that the triple bond starts at the second carbon atom in the chain.
Unlike 1-butyne, both ends of the molecule in 2-butyne are bonded to a CH₃ (methyl) group, creating a symmetrical structure.

alkynes

Alkynes are a family of hydrocarbons that contain at least one carbon-carbon triple bond. This triple bond gives alkynes unique chemical and physical properties compared to other hydrocarbons like alkanes and alkenes. The general formula for alkynes is CₙH₂ₙ₋₂.
In terms of bonding, the triple bond consists of one sigma bond and two pi bonds, which contribute to the rigidity and linearity of alkynes.
Because of this specific bonding, alkynes are generally more reactive than their single-bonded (alkane) and double-bonded (alkene) counterparts.

condensed structural formulas

Condensed structural formulas are a way to represent the structure of molecules without drawing out every single bond and atom. These formulas provide a shorthand way of detailing how atoms are connected in a molecule.
For alkynes like 1-butyne and 2-butyne, condensed formulas use special symbols and placements to indicate the triple bonds (≡). For example, CH≡C-CH₂-CH₃ for 1-butyne specifies the triple bond between the first and second carbons.
Condensed structural formulas are useful for simplifying complex organic molecules and are commonly used in chemical literature and problem-solving.

carbon chain

A carbon chain is a series of carbon atoms connected together in a molecule. Carbon chains serve as the backbone of many organic molecules. They can vary in length and can be either straight (linear) or branched.
In molecules like 1-butyne and 2-butyne, the carbon chain consists of four carbons, hence the 'but-' prefix. The length and arrangement of the carbon chain can affect the properties and reactivity of the molecule.
Carbon chains can include single, double, or triple bonds, which will significantly affect the chemical nature of the compound.