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🥼organic chemistry review

Ethyl Radical

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

Definition

The ethyl radical is a reactive organic species consisting of a carbon atom with three hydrogen atoms and one unpaired electron. It is an important intermediate in various chemical reactions, particularly in the context of the stability of the allyl radical and the concept of resonance.

5 Must Know Facts For Your Next Test

  1. The ethyl radical is formed by the homolytic cleavage of the carbon-hydrogen bond in ethane, resulting in the formation of a reactive species with an unpaired electron.
  2. The stability of the ethyl radical is relatively low compared to other radical species, as it lacks the ability to form resonance structures that would delocalize the unpaired electron.
  3. In the context of the stability of the allyl radical, the ethyl radical serves as a point of comparison, as the allyl radical is significantly more stable due to its ability to form resonance structures.
  4. The increased stability of the allyl radical compared to the ethyl radical is a result of the delocalization of the unpaired electron across the three carbon atoms, which is facilitated by the presence of the two carbon-carbon double bonds.
  5. The concept of resonance is crucial in understanding the relative stability of the ethyl and allyl radicals, as it explains how the delocalization of electrons can contribute to the overall stability of a radical species.

Review Questions

  • Explain the relationship between the ethyl radical and the stability of the allyl radical.
    • The ethyl radical, with its relatively low stability, serves as a point of comparison to highlight the increased stability of the allyl radical. The allyl radical is more stable than the ethyl radical due to its ability to form resonance structures, which allow for the delocalization of the unpaired electron across the three carbon atoms. This delocalization, facilitated by the presence of the two carbon-carbon double bonds, contributes to the enhanced stability of the allyl radical compared to the ethyl radical, which lacks the ability to form such resonance structures.
  • Describe how the concept of resonance relates to the stability of the ethyl and allyl radicals.
    • The concept of resonance is crucial in understanding the relative stability of the ethyl and allyl radicals. Resonance allows for the delocalization of electrons, which contributes to the overall stability of a molecule or ion. In the case of the allyl radical, the presence of the two carbon-carbon double bonds enables the formation of resonance structures, leading to a more stable configuration compared to the ethyl radical. The ethyl radical, on the other hand, lacks the ability to form resonance structures, resulting in a lower overall stability. The increased stability of the allyl radical due to resonance is a key factor in the context of understanding the stability of the allyl radical.
  • Analyze the factors that contribute to the difference in stability between the ethyl radical and the allyl radical.
    • The primary factor that contributes to the difference in stability between the ethyl radical and the allyl radical is the ability to form resonance structures. The allyl radical, with its two carbon-carbon double bonds, can delocalize the unpaired electron across the three carbon atoms, resulting in a more stable configuration. This delocalization is facilitated by the concept of resonance, where the allyl radical can be represented by multiple equivalent Lewis structures. In contrast, the ethyl radical lacks the ability to form resonance structures, leading to a relatively lower stability. Additionally, the presence of the two carbon-carbon double bonds in the allyl radical provides further stabilization through the delocalization of the unpaired electron, contributing to its increased stability compared to the ethyl radical.