9The Zaitsev RuleThe more substituted alkene product is obtained when aproton is removed from the b-carbon that is bondedto the fewest hydrogensThe most stable alkene is generally (but not always) themost substituted alkene
39Utilization of kinetic isotope effect to study a reaction mechanism kHkDA carbon deuterium bond (C–D) is stronger than a carbon hydrogen bond (C–H)The deterium isotope is 7.1, indicating that C–H (or C–D)bond must be broken in the rate-determining step
40Competition Between Substitution and Elimination Alkyl halides can undergo SN2, SN1, E2 and E11) decide whether the reaction conditions favor SN2/E2 or SN1/E1SN2/E2 reactions are favored by a highconcentration of nucleophile/strong baseSN1/E1 reactions are favored by a poornucleophile/weak base2) decide how much of the product will be the substitution productand how much of the product will be the elimination product
49Intermolecular Versus Intramolecular Reactions A low concentration of reactant favors an intramolecularreactionThe intramolecular reaction is also favored when a five-or six-membered ring is formed
50Three- and four-membered rings are less easily formed Three-membered ring compounds are formed moreeasily than four-membered ring compoundsThe likelihood of the reacting groups finding each otherdecreases sharply when the groups are in compoundsthat would form seven-membered and larger rings.