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🥼organic chemistry review

2,2-dimethylpropene

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

2,2-dimethylpropene, also known as tert-butylethylene, is an alkene with a highly branched structure that exhibits unique stability and reactivity characteristics, particularly in the context of understanding the factors that influence the stability of alkenes.

5 Must Know Facts For Your Next Test

  1. The presence of two methyl groups at the 2-position of the double bond in 2,2-dimethylpropene creates significant steric hindrance, which contributes to its enhanced stability.
  2. The highly branched structure of 2,2-dimethylpropene allows for effective hyperconjugation, where the sigma bonds of the methyl groups interact with the adjacent pi bond, further stabilizing the molecule.
  3. Compared to less substituted alkenes, 2,2-dimethylpropene exhibits increased resistance to electrophilic addition reactions due to the steric and electronic factors that stabilize the molecule.
  4. The stability of 2,2-dimethylpropene makes it a useful model compound for understanding the factors that influence the stability of alkenes, which is a key concept in organic chemistry.
  5. The enhanced stability of 2,2-dimethylpropene is a result of the interplay between steric hindrance, hyperconjugation, and the overall electronic structure of the molecule.

Review Questions

  • Explain how the structure of 2,2-dimethylpropene contributes to its increased stability compared to less substituted alkenes.
    • The presence of two methyl groups at the 2-position of the double bond in 2,2-dimethylpropene creates significant steric hindrance, which makes it more difficult for electrophiles to approach the double bond. This steric factor, combined with the ability of the methyl groups to engage in hyperconjugation with the adjacent pi bond, significantly stabilizes the molecule. The interplay between these structural features results in 2,2-dimethylpropene being more resistant to electrophilic addition reactions compared to less substituted alkenes.
  • Describe how the concept of hyperconjugation applies to the stability of 2,2-dimethylpropene.
    • Hyperconjugation, the stabilizing interaction between a sigma bond and an adjacent pi bond, plays a crucial role in the stability of 2,2-dimethylpropene. The highly branched structure of the molecule allows the sigma bonds of the methyl groups to effectively overlap with the pi bond of the double bond, resulting in increased electron delocalization and stabilization of the molecule. This hyperconjugative effect, in addition to the steric hindrance provided by the methyl groups, contributes to the enhanced stability of 2,2-dimethylpropene compared to less substituted alkenes.
  • Evaluate the importance of understanding the stability of 2,2-dimethylpropene in the broader context of the stability of alkenes.
    • Understanding the factors that contribute to the stability of 2,2-dimethylpropene, such as steric hindrance and hyperconjugation, is crucial in the broader context of comprehending the stability of alkenes. As a highly substituted alkene, 2,2-dimethylpropene serves as a model compound for studying how structural features can influence the reactivity and stability of alkenes. By analyzing the unique stability of 2,2-dimethylpropene, students can gain insights into the general principles governing the stability of alkenes, which is a fundamental concept in organic chemistry. This understanding can then be applied to predict and rationalize the behavior of a wide range of alkene compounds in various reactions and contexts.