Question

\[\begin{array}{cc}\phantom{......}\ce{OH}\\
\phantom{....}|\\\ce{CH3CH2 - C - CH3}\\
\phantom{....}|\\\phantom{.....}\ce{Ph}\end{array}\] cannot be prepared by ______.

Options

• \[\ce{CH3CH2COCH3 + PhMgX}\]

• \[\ce{PhCOCH2CH3 + CH3MgX}\]

• \[\ce{PhCOCH3 + CH3CH2MgX}\]

• \[\ce{HCHO + PhCH(CH3)CH2MgX}\]

Answer 1

\[\begin{array}{cc}\phantom{......}\ce{OH}\\
\phantom{....}|\\\ce{CH3CH2 - C - CH3}\\
\phantom{....}|\\\phantom{.....}\ce{Ph}\end{array}\] cannot be prepared by \[\underline{\ce{HCHO + PhCH(CH3)CH2MgX}}\].

Explanation:

Tertiary alcohol is prepared by the reaction of Grignard reagent with a ketone (formaldehyde is used to prepare primary alcohol).

\[\begin{array}{cc}
\ce{O}\phantom{........................................................}\\
||\phantom{........................................................}\\
\ce{H - C - H + PhCH(CH3)CH2MgX ->[H3O+] HOCH2 - CH2 - CH - Ph}\\
\phantom{...................................................}|\\
\phantom{......................................................}\ce{CH3}
\end{array}\]