Predict al the alkenes that would be formed by dehyddrohalogenation 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) 3-Bromo-2,2,3-trimethylpentane.

Predict al the alkenes that would be formed by dehyddrohalogenation of

1.	Predict al the alkenes that would be formed by dehyddrohalogenation 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) 3-Bromo-2,2,3-trimethylpentane.
Answer» SOLUTION :(i) In 1-bromo-1-methylcyclohexane, the `beta`-hydrogens on either side of the Br atom are equivalent, THEREFORE, only 1-alkene is formed. (ii) 2-Chloro-2-methylbutane has two different sets of equivalent `beta`-hydrogens and hence, in PRINCIPLE, can GIVE two alkenes (I and II). but according to Sayzeff rule, more highly substituted alknene (II), being more stable, is the major product. `underset("2-Chloro-2-methylbutane")(overset(beta)(C)H_(3)-underset(Cl)underset(\|)overset(overset(beta)(C)H_(3))overset(\|)(C)-overset(beta)(C)H_(2)CH_(3)) underset(-(HCl))overset(C_(2)H_(5)ON a//C_(2)H_(5)OH)to underset("2-Methylbut-1-ene (I) (Less stable, minor product)")(CH_(2)=overset(CH_(3))overset(\|)(C)-CH_(2)CH_(3))+underset("2-Methylbut-2-ene (II) (More stable, major product)")(CH_(3)-overset(CH_(3))overset(\|)(C)=CHCH_(3))` (iii) 3-Bromo-2,2,3-trimethylpentane has two different sets of `beta`-hydrogens and hence, in principle, can give two alkenes (I and II)). but according to Saytzeff rule, more highly substituted alkene (II), being more stable, is the major product.