Question

Identify 'Z' in the following series of reaction:

\[\ce{Butan - 2 - ol ->[PCl3] X ->[alco. KOH] Y ->[i) H2SO4][ii) H-OH/heat] Z}\]

विकल्प

• 2-Chlorobutane

• Butan-1-ol

• Butan-2-ol

• But-2-ene

Answer 1

Butan-2-ol

Explanation:

(i)
\[\begin{array}{cc}
\ce{3CH3 - CH2 - CH - CH3 + PCl3 ->[\Delta] 3CH3 - CH2 - CH - CH3 + H3PO3}\\
|\phantom{.....................................}|\phantom{...}\\
\phantom{.....}\ce{\underset{\text{Butan- 2- ol}}{OH}}\phantom{.........................}\ce{\underset{\text{(X)}}{\underset{\text{2 - Chlorobutane}}{Cl}}}\end{array}\]

(ii)

\[\begin{array}{cc}
\ce{2CH3 - CH2 - CH - CH3 + \underset{\text{(alc.)}}{2KOH} ->[\Delta] CH3 \underset{\text{(Y)}}{\underset{\text{(Major)}}{\underset{\text{But-2-ene}}{- CH = CH}}} - CH3 + CH3 \underset{\text{(Minor)}}{\underset{\text{But-1-ene}}{- CH2 - CH}} = CH2 + 2KCl + 2H2O}\\
|\phantom{.............................................................................}\\
\ce{\underset{\text{(X)}}{\underset{\text{2- Chlorobutane}}{Cl}}}\phantom{........................................................................}\end{array}\]

(iii)

\[\begin{array}{cc}
\ce{\underset{\text{(Y)}}{\underset{\text{But-2-ene}}{CH3 - CH = CH}} - CH3 ->[(i) H2SO4] CH3 - CH2 - CH - CH3 ->[(ii) H - OH/heat] CH3 - CH2 - CH - CH3 + H2SO4}\\
\phantom{................................}|\phantom{......................................}|\phantom{..}\\
\phantom{......................................}\ce{OSO3H}\phantom{..............................}\ce{\underset{\text{(Z)}}{\underset{\text{Butan-2-ol}}{OH}}}\phantom{..}
\end{array}\]