$1-$ બ્યુટાઇન
$\rightleftharpoons \begin{array}{*{20}{c}}
{\,\,\,\,\,\,\,\,\,\,\,\,\,O} \\
{\,\,\,\,\,\,\,\,\,\,\,\,\,||} \\
{C{H_3}C{H_2} - C = C{H_3}}
\end{array}$
$2-$ બ્યુટેનોન
એસીટાલ $-$ હિમિએસીટાલ
$(1)$ $\begin{matrix}
O \\
|| \\
{{C}_{6}}{{H}_{5}}-C-{{C}_{6}}{{H}_{5}} \\
\end{matrix}$
$(2)$ $C _{6} H _{5}- CHO$
$(3)$ $p - CH _{3}- C _{6} H _{4}- CHO$
$(4)$ $p - CH _{3} O - C _{6} H _{4}- CHO$