Question

Identify the CORRECT stability order of alkyl substituted alkenes from following.

Options

• R₂C = CHR > R₂C = CH₂ > R₂C = CR₂

• R₂C = CR₂ > R₂C = CHR > R₂C = CH₂

• R₂C = CH₂ > R₂C = CR₂ > R₂C = CHR

• R₂C = CR₂ > R₂C = CH₂ > R₂C = CHR

Answer 1

R₂C = CR₂ > R₂C = CHR > R₂C = CH₂

Explanation:

Alkene stability increases with the number of alkyl substituents because alkyl groups stabilize the C = C bond by hyperconjugation and electron‑donating (inductive) effects, so tetrasubstituted > trisubstituted > disubstituted. This trend is confirmed by hydrogenation heats of reaction (more stable alkenes yield less exothermic hydrogenation).