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Chemistry LibreTexts

Zaitsev's Rule

Zaitsev's Rule can be used to predict the regiochemistry of elimination reactions.

Introduction

Zaitsev’s or Saytzev’s (anglicized spelling) rule is an empirical rule used to predict regioselectivity of 1,2-elimination reactions occurring via the E1 or E2 mechanisms. It states that in a regioselective E1 or E2 reaction the major product is the more stable alkene, (i.e., the alkene with the more highly substituted double bond). For example:

 

E1 reaction always follow Zaitsev’s rule; with E2 reactions, there are exceptions (see antiperiplanar).