$CH_3CHO$ $ +$ $CH_3Mgl $ $\xrightarrow {\,\,\,\,}$ $X$ $\xrightarrow {H_2O/H^+}$ $Y$
$\xrightarrow{{{H_2}O/{H^ + }}} \,$ $\begin{array}{*{20}{c}}
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,{OH} \\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, | \\
{C{H_3} - CH} \\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,| \\
\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{C{H_3}} \\
{(Y)}
\end{array} \,\,+ \,Mg < \begin{array}{*{20}{c}}
{OH} \\
I
\end{array}$