Allylic Halides Cheat Sheet

Key Definitions

• Allylic Halides: Organic compounds where a halogen atom is bonded to an allylic carbon (the carbon adjacent to a double bond). ✅

• Nucleophilic Substitution: A reaction where a nucleophile replaces a leaving group in a compound. ✅

Important Concepts

Structure and Reactivity

• Allylic Position: The carbon atom adjacent to the carbon of a double bond.

• Stability: Allylic halides are more stable due to resonance, allowing for delocalization of electrons. ✅

Types of Reactions

• SN1 Mechanism: Unimolecular nucleophilic substitution; involves carbocation formation. ✅

• SN2 Mechanism: Bimolecular nucleophilic substitution; involves a direct attack by the nucleophile. ✅

Key Formulas

• k: rate constant

• [R-X]: concentration of allylic halide

Common Mistakes to Avoid

Common Mistake: Confusing SN1 and SN2 mechanisms; remember SN1 involves carbocation stability while SN2 involves direct attack.

Memory Tricks

Tip: "SN1 = Slow, Nucleophile 1" — SN1 is a two-step process with one molecule in the rate-determining step.

Key Diagrams

Allylic Halide Structure:
      H     H
       \   /
        C=C
       /   \
      R     X

• R: Alkyl group

• X: Halogen (F, Cl, Br, I)

Nucleophilic Substitution Mechanism (SN2):
      Nu:- + R-X → Nu-R + X:-