e.g. 1. \[\begin{array}{cc} \ce{O\phantom{……………………………}}\ce{O\phantom{………………}}\ce{H\phantom{}}\\ ||\phantom{……………………………}||\phantom{……………….}|\\ \ce{\underset{\text{Formaldehyde}}{2H – C – H} + \underset{\text{Sodium hydroxide (50%)}}{NaOH} ->[\triangle] \underset{\text{Sodium formate}}{H – C – O- Na+} + H – C – OH}\\\phantom{………………………………………………}|\\\ce{\phantom{………………………………………………}\underset{\text{Methanol}}{H}}\end{array}\]