# Primary kinetic isotope effect in the E1cB reaction

How is the primary kinetic isotope effect (KIE) observed in the E1cB reaction when breaking of the $$\ce{C}$$-$$\ce{H}$$ bond is not the rate determining step of this reaction?

• There is a section on Wikipedia describing KIEs in the E1cb reaction in quite some detail: en.wikipedia.org/wiki/… Have you already seen that? Is there something specific you don't understand about it? – orthocresol Apr 14 '19 at 9:22
• Is it like....1) A Deuterium 'Exchange' indicates that an E1CB REVERSIBLE reaction has taken place, & ...2) A beta deuterium substituted reactant showing primary kinetic isotopic effect indicates that an E1CB IRREVERSIBLE reaction has taken place? I'm confused. Please help. – Anonymous Apr 14 '19 at 11:15