CHEM 203 Lecture Notes - Lecture 24: Steric Effects, Elimination Reaction, Proton Affinity
Document Summary
Formation of alkenes (= olefin) upon the reaction of tertiary halides with basic agents: generic base. + br in the example above, the molecule of tert-butyl bromide eliminates (i. e. , it expels) hbr to form the alkene, 2-methyl-2-propene (isobutene) the addition of hbr to 2-methyl-2-propene would lead to 2-bromo-2-methylpropane. But in the above transformation, a molecule of 2-bromo-2-methylpropane eliminates (=loses, or expels) So, the reaction is formally the inverse of an addition process. Description of the above process as an elimination reaction: one leading to formation of a double bond through expulsion of appropriate fragments from a substrate molecule. The elimination reaction as formally the reverse of an addition reaction: Nature of the basic agent required to induce the above elimination reaction: conjugate base of a weak acid with pka 4-5. Bronsted basic properties (pka of conjugate acid 5) of the nucleophiles commonly employed in sn2 reactions (notes of oct. 27)
