Illustrated Glossary of Organic Chemistry

Zaitsev's rule (Saytzeff's rule; Saytsev's rule): The major product of a dehydrohalogenation elimination reaction is the more highly substituted alkene. The rule does not apply to eliminations other than dehydrohalogenation.




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Trisubstituted alkene
Disubstituted alkene

Base = -OCH2CH3
79%

21%
This E2 elimination reaction obeys Zaitsev's rule.







Base = -OC(CH3)3
27%

73%
This Hofmann elimination reaction does not obey Zaitsev's rule.