Why do only compounds that yield tertiary carbocations (or resonance‐stabilized carbocations) undergo SN1?
Compounds that yield tertiary or resonance‐stabilized carbocations undergo
You always have a competition between the
t-Butyl bromide is extremely hindered to back-side attack. So the
But both hyperconjugation and the electron-donating effects of the alkyl groups stabilize the 3° carbocation.
Allyl bromide, CH₂=CH-CH₂Br, is a 1° halide. The
But resonance stabilizes the allyl cation, CH₂=CH-CH₂⁺.