Reactions of Alkenes
Reactions of Amines
|Elimination reactions where a quaternary ammonium ion is the leaving group obey the Hofmann rule, yielding the less substituted alkene. This is the opposite of the Zaitsev rule. The reason is that with base-promoted elimination of an alkyl halide, the transition state has substantial double bond character, but in this case, with the presence of a strongly electron withdrawing, positively charged, nitrogen, the activated complex has character substantially determined by the carbon-hydrogen bond cleavage. The β-hydrogen is extracted by the base from the least hindered carbon.|
While the Hofmann rule is not required prior knowledge for the MCAT, it would be an ideal passage topic on the test.