Saytzeff rule

Synonym: Zaitsev rule
Dehydrohalogenation of secondary- and tertiary-alkyl halides proceeds by the preferential removal of the β-hydrogen from the carbon that has the smallest number of hydrogens. Originally formulated by A. Saytzeff (Zaitsev) to generalize the orientation in β-@E02038@ reactions of alkyl halides, this rule has been extended and modified, as follows: When two or more @O04281@ can be produced in an @E02038@ reaction, the thermodynamically most @S05900@ alkene will predominate. Exceptions to the Saytzeff rule are exemplified by the @H02830@.
See also:
Markownikoff rule
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1162 [Terms] [Paper]