Substitution - Elimination Review 

Substitution -Elimination Review review and review.

 

Organic chemistry Sn1 Sn2 E1 E2

Summary of Halide Reactivity ( primary, secondary or tertiary product)

SN2 SN1
1  halide

2 halide

3 ( hindrance)

3

2

X  ( SN1 has no primary product unless **)
E2 E1
3

2

1

 3

2

X ( E1 has no primary product)

**there are allylic structure or hydride shift to a more stable cation

How to read this chart above? When Nu: attacked the primary in SN2, there is a fastest reaction them tertiary. SN2 is favor primary halide.

 Structure Recognizaion

Benzylic Halid, Allylic Halid, Vinylic Halid and Aryl Halides

  Benzylic Halid, Allylic Halid, Vinylic Halid and Aryl Halides

 

In Substitution or Elimination, a Nucleophihle reacts with halide. Considering nucelophile is an attacker, the reactivity between an attacker and halide will depends how well the leaving group on alkyl halide.

Exam Strategies:

If you see solvent CH3OH only, without other stuffs in that line, remember SN1 and E1 loves these kinds of solvent, the products therefore can be either SN1 or E1.  Don't be surprised a question worth 15 points  because there could be many products to draw under different conditions.

To distinct Sn2 and E2 is based on the condition where E2 require stronger base to plug out hydrogen. See an extra solvent, it could be E2. Usually E2 has 3>2>1 while Sn2 favors  1>2>3 halide.

  

 

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