Question

Convert the following:

Acetaldehyde to But-2-enal

Answer 1

Aldol condensation (in presence of dil. \[\ce{NaOH}\]) followed by dehydration.

\[\begin{array}{cc}
\phantom{}\ce{\underset{Acetaldehyde}{CH3CHO} ->[dil. NaOH] CH3 - CH - CH2 - CHO ->[Δ][-H2O] \underset{\underset{(Adol condensation product)}{But-2-enal}}{CH3 - CH} = CH - CHO}\\
|\phantom{.........................}\\
\ce{\underset{\underset{(Adol)}{3-Hydroxybutanal}}{OH}}\phantom{.......................}\\
\end{array}\]