DISFAVORED: No reaction! Primary alkyl halide, but extreme beta-branching (neo-pentyl group) is too stericly crowded for Sn2 and no beta-Hydrogens exist for E2

Note: Stereospecific E2 requires proton and leaving group to be anti-periplanar

Note: Stereospecific E2 requires proton and leaving group to be anti-periplanar, even though this results in the largest substituents being cis to each other

Note: Stereospecific E2 requires proton and leaving group to be anti-periplanar. Within ring system, this means they must assume a trans-diaxial conformation

Note: E1 results in racemization, no stereospecificity. Always prefer the larger groups trans to each other

Note: Sn1 competition. Note that a carbocation rearrangement (hydride shift) occured

Note: E1 results in racemization, no stereospecificity. Always prefer the larger groups trans to each other

Note: Sn1 competition. Note that a carbocation rearrangement (hydride shift) occured

Note: E2 elimination as usual, Zaitsev rule preference for more highly substituted alkene

Caution: Bulky base AND bulky alkyl halide. Anti-Zaitsev preference for LEAST substituted alkene

Note: Elimination preference for more stable alkene, which is not necessarily the most substituted. Conjugated alkene is much more stable.

Note: 1st equivalent of base yields elimination with Zaitsev preference for more highly substited alkene

Note: 2nd equivalent of base yields elimination with selectivity for more stable conjugated alkene

Note: Sn2 at primary benzylic halide

Note: Sn1 at primary benzylic halide. Apparent primary carbocation seems disfavored, but resonance at the benzylic position stabilizes it

Note: Intramolecular Sn2. 3-ring works to make epoxide

Note: Intramolecular Sn2. 5-ring highly favorable

Note: Intramolecular Sn2. 6-ring highly favorable