question_answer 19)

Predict all the alkanes that would be formed bydehydrohalogenation of the following halides with sodium ethoxide in ethanol and identify the major alkene: (i) 1-bromo-1-methylcyclohexane (ii) 2-chloro-2-methylbutane (iii) 2,2,3-triniethyl-3-bromopentane  

Answer:

    On reacting with sodium ethoxide in ethanol, the H-atom from p-carbonatom is eliminated. This is called p-elimination. Simultaneously,elimination of halogen atom from a-carbon takes place.   (i) 1-bromo-1-methylcyclohexane has two -hydrogen atoms. So, two products will be formed. NoteSaytzeff's rule: The product is preferred in which thecarbon atoms joined by double bond are more alky] substituted oralkylated. (ii)                   (iii)