Question

What happens when methanal undergoes cannizzaro reaction?

Answer 1

When methanal (formaldehyde, HCHO) undergoes the Cannizzaro reaction, it results in the formation of formic acid HCOOH and methanol CH₃OH.

The Cannizzaro reaction is a base-catalyzed disproportionation reaction that occurs with non-alpha-hydrogenated aldehydes (like methanal). In this reaction, one molecule of formaldehyde gets reduced to methanol CH₃OH, while the other gets oxidized to formic acid HCOOH.

The reaction can be represented as:

\[\ce{2HCHO ->[NaOH] HCOOH + CH3OH}\]

Answer 2

Methanal will undergo Cannizzaro reaction as it possesses α-hydrogen to form methanol.
\[\begin{array}{cc}
\phantom{.}\ce{H}\phantom{..............................}\ce{H}\phantom{.......}\ce{H}\phantom{...........}\phantom{..}\\
\backslash\phantom{..............................}|\phantom{.........}\backslash\phantom{..........}\\
\ce{2C = O + conc.KOH -> H - C - OH + C - O- K+}\\
/\phantom{..............................}|\phantom{.........}/\phantom{..........}\\
\ce{\underset{Methanal}{H}}\phantom{.........................}\ce{\underset{Methanol}{H}}\phantom{.}\ce{\underset{methanoate}{\underset{Potassium}{H}}}\phantom{............}\\
\end{array}\]