Question

Account for the following:

Ethanol gives iodoform reaction whereas methanol does not give iodoform reaction.

Answer 1

Iodoform reaction is given by ketone having methyl group attached to carbonyl carbon. Any compound that can be oxidised to a methyl Ketone gives iodoform test. Hence, ethyl alcohol is oxidised acetaldehyde with \[\begin{array}{cc}\ce{CH3 - C - H}\\\phantom{...}||\\ \phantom{...}\ce{O}\end{array}\] group formation and provides an iodoform with test, whereas methyl alcohol \[\ce{(CH3 - OH)}\] does not give an iodoform reaction because methyl alcohol cannot be oxidised to a compound containing methyl keto group as methyl alcohol has only one carbon atom.