2,3-dimethylbutane

Definition

2,3-dimethylbutane is an alkane with the chemical formula C6H14. It is a branched-chain isomer of the straight-chain alkane hexane, featuring two methyl (CH3) groups attached to the second and third carbon atoms of the four-carbon backbone.

5 Must Know Facts For Your Next Test

1. 2,3-dimethylbutane has a total of 6 carbon atoms and 14 hydrogen atoms.
2. The presence of two methyl groups at the second and third carbon positions creates a branched structure, which differentiates it from the straight-chain isomer, n-hexane.
3. Branched-chain alkanes like 2,3-dimethylbutane generally have lower boiling points compared to their straight-chain counterparts due to weaker intermolecular forces.
4. The branching in 2,3-dimethylbutane results in a more compact molecular structure, leading to a higher octane rating and better performance in internal combustion engines.
5. 2,3-dimethylbutane is a common constituent of gasoline and is also used as a fuel additive to improve combustion efficiency.

Review Questions

• Explain how the branched structure of 2,3-dimethylbutane affects its physical and chemical properties compared to a straight-chain alkane.
  • The branched structure of 2,3-dimethylbutane, with two methyl groups attached to the second and third carbon atoms, results in a more compact molecular arrangement compared to a straight-chain alkane like n-hexane. This compact structure leads to weaker intermolecular forces, which in turn lowers the boiling point of 2,3-dimethylbutane. Additionally, the branching creates a more efficient packing of the molecules, leading to a higher octane rating and improved performance in internal combustion engines.
• Describe the relationship between the molecular formula of 2,3-dimethylbutane and its classification as an alkane and an isomer.
  • The molecular formula of 2,3-dimethylbutane is C6H14, which is characteristic of alkanes, a class of saturated hydrocarbons with the general formula CnH2n+2. The presence of six carbon atoms and fourteen hydrogen atoms in the 2,3-dimethylbutane molecule confirms its classification as an alkane. However, the specific arrangement of the carbon and hydrogen atoms, with the two methyl groups attached to the second and third carbon positions, differentiates 2,3-dimethylbutane from the straight-chain isomer, n-hexane. This branched structure makes 2,3-dimethylbutane an isomer of n-hexane, as both molecules share the same molecular formula but have different spatial arrangements of the atoms.
• Analyze the significance of 2,3-dimethylbutane as a component of gasoline and its role in improving combustion efficiency.
  • 2,3-dimethylbutane is a common constituent of gasoline due to its desirable properties for internal combustion engines. The branched structure of 2,3-dimethylbutane results in a higher octane rating, which is a measure of a fuel's resistance to premature ignition or 'knocking' during combustion. This higher octane rating allows for more efficient combustion, leading to improved engine performance and fuel economy. Additionally, the compact molecular structure of 2,3-dimethylbutane contributes to its use as a fuel additive, as it can be blended with other gasoline components to enhance the overall combustion efficiency of the fuel mixture.

Related terms

Alkanes:

Saturated hydrocarbons with the general formula CnH2n+2, where n is the number of carbon atoms.

Isomers:

Molecules that have the same molecular formula but different arrangements of atoms in space, resulting in different properties.

Branched-chain Alkanes: Alkanes with one or more alkyl substituents (such as methyl or ethyl groups) attached to the carbon chain.