Question

tert-Butyl alcohol, when heated with $H_{2}S{O}_4$, gives an alkene. Which of the following sequence will convert the alkene to 3-methylbutanoic acid?

1 - $H_3{O}^{+},$ hydrolysis

2 – treatment with $C{N}^{-}$

3 – $HBr,$ peroxide

• A. 3; 2; 1
• B. 2; 1; 3
• C. 3; 1; 2
• D. 1; 2; 3

Answer 1

The correct option is A

3; 2; 1

First, we convert the tertiary substrate to 2-methylpropene via dehydration.
The alkene is then converted to a primary alkylbromide via an anti-Markovnikov addition of $HBr$.
Using a substitution reaction, the $C{N}^{-}$ replaces bromide. The nitrile is hydrolysed to give the acid: