Question

Which of the following reactions is used to prepare isobutane ?

• A. Wurtz reaction of $C_2{H}_{5}Br$
• B. Hydrolysis of n-butylmagnesium iodide
• C. Reduction of propanol with red phosphorus and $HI$
• D. Decarboxylation of 3-methylbutanoic acid

Answer 1

Answer: (D)

$\underset{\text{3-methylbutanoic acid}}{C{H}_3-\underset{\stackrel{|}{C{H}_3}}{\mathrm{CH}}-C{H}_{2}COOH}\underset{\mathrm{\Delta }}{\overset{\text{NaOH/CaO}}{\to }}$
$C{H}_3-\underset{\stackrel{|}{\underset{\text{Isobutane}}{C{H}_3}}}{\mathrm{CH}}-C{H}_3+C{O}_2\uparrow$
On the other hand Wurtz reaction of $\mathrm{C}{}_2\mathrm{H}{}_5\mathrm{Br}$ gives. n-butane and hydrolysis of n-butyl magnesium bromide gives n-butane but reduction of propanol with HI/P gives propane.