Core reactions
Instead of memorizing hundreds of transformations, learn a few families and the driving force behind each.
This page summarizes the “high-yield” sets with reagent tables.
Alkene additions (selectivity = mechanism)
| Transformation | Reagents | Outcome | Stereo |
|---|
| Hydrohalogenation | HX | Markovnikov (carbocation-like) | not stereospecific |
| Hydration | H₃O⁺ (acid-catalyzed) | Markovnikov alcohol | rearrangements possible |
| Oxymercuration | Hg(OAc)₂, H₂O; then NaBH₄ | Markovnikov alcohol | no rearrangements |
| Hydroboration-oxidation | BH₃·THF; then H₂O₂, OH⁻ | anti-Markovnikov alcohol | syn addition |
| Bromination | Br₂ | vicinal dibromide | anti addition |
| Epoxidation | mCPBA | epoxide | syn (concerted) |
| Hydrogenation | H₂, Pd/C | alkane | syn addition |
Carbonyl chemistry cheat sheet
| Carbonyl | Nucleophile | Product | Notes |
|---|
| aldehyde/ketone | NaBH₄ | alcohol | mild reducing agent |
| aldehyde/ketone | LiAlH₄ | alcohol | strong; reacts with water |
| acyl derivative | RMgX / RLi | alcohol (often 2 additions) | esters → 3° alcohol after 2 additions |
| aldehyde/ketone | HCN / CN⁻ | cyanohydrin | adds “C≡N” handle |
| aldehyde/ketone | amine (acid cat.) | imine/enamine | forms C=N; enamine acts as nucleophile |
Aromatic EAS quick table
| Reaction | Reagents | Electrophile |
|---|
| Bromination | Br₂, FeBr₃ | Br⁺ |
| Nitration | HNO₃, H₂SO₄ | NO₂⁺ |
| Sulfonation | SO₃, H₂SO₄ | SO₃H⁺ |
| Friedel–Crafts alkylation | R–Cl, AlCl₃ | R⁺ (carbocation-like) |
| Friedel–Crafts acylation | RCOCl, AlCl₃ | acylium (R–C≡O⁺) |
Directing effects: EDGs activate and direct o/p; EWGs deactivate and direct meta (halogens are the classic exception).