key term - 2-methyl-2-butene

Definition

2-methyl-2-butene is an alkene with the molecular formula C₅H₁₀. It is a structural isomer of 2-butene, with a methyl group (CH₃) attached to the central carbon atom of the alkene. This term is important in the context of understanding the stability of alkenes and the stability of the allyl radical.

5 Must Know Facts For Your Next Test

1. The presence of the methyl group in 2-methyl-2-butene contributes to the increased stability of the alkene compared to other alkenes without substituents.
2. The allyl radical formed from 2-methyl-2-butene is also more stable due to resonance delocalization of the unpaired electron across the three-carbon system.
3. The stability of 2-methyl-2-butene and its allyl radical is a result of the ability to distribute the electron density across multiple carbon atoms, reducing the overall energy of the system.
4. The increased stability of 2-methyl-2-butene and its allyl radical makes them more likely to undergo certain chemical reactions, such as electrophilic addition and radical substitution.
5. The stability of 2-methyl-2-butene and its allyl radical is an important concept in understanding the reactivity and behavior of alkenes in organic chemistry.

Review Questions

• Explain how the presence of the methyl group in 2-methyl-2-butene contributes to the increased stability of the alkene.
  • The methyl group (CH₃) attached to the central carbon atom of 2-methyl-2-butene provides additional electron density and stabilization through hyperconjugation. This hyperconjugative interaction between the σ-bond of the methyl group and the π-bond of the alkene helps to delocalize the electrons, resulting in a more stable alkene structure compared to alkenes without substituents.
• Describe the stability of the allyl radical formed from 2-methyl-2-butene and explain how resonance contributes to this stability.
  • The allyl radical formed from the removal of a hydrogen atom from 2-methyl-2-butene is a resonance-stabilized radical. The unpaired electron can be delocalized across the three-carbon system, with the radical character being shared between the two terminal carbon atoms and the central carbon atom. This resonance stabilization lowers the overall energy of the radical species, making it more stable compared to non-resonance-stabilized radicals.
• Discuss the implications of the increased stability of 2-methyl-2-butene and its allyl radical on the reactivity and behavior of this alkene in organic chemistry reactions.
  • The enhanced stability of 2-methyl-2-butene and its allyl radical makes them more likely to participate in certain organic chemistry reactions, such as electrophilic addition and radical substitution. The stabilization provided by the methyl group and the resonance delocalization of the allyl radical reduces the activation energy required for these reactions, making them more favorable to occur. This increased reactivity and stability can influence the reaction pathways, product distributions, and the overall behavior of 2-methyl-2-butene in various organic chemistry contexts.

Related terms

Alkene:

An unsaturated hydrocarbon compound containing a carbon-carbon double bond.

Allyl Radical:

A resonance-stabilized radical species formed by the removal of a hydrogen atom from an alkene, such as 2-methyl-2-butene.

Resonance:

The ability of a molecule or ion to be represented by multiple valid Lewis structures, leading to the delocalization of electrons and increased stability.