Iodoform ($$\text{CHI}_3$$) Uses & Test

• Iodoform Reaction (General Equation):

$$\begin{aligned}\text{R--COCH}_3 + 3\text{I}_2 + 4\text{NaOH} \to \text{R--COONa} + \text{CHI}_3 \downarrow \text{ (Bright Yellow)} + 3\text{NaI} + 3\text{H}_2\text{O}\end{aligned}$$

• For Ethanol:

$$\text{CH}_3\text{CH}_2\text{OH} + 4\text{I}_2 + 6\text{NaOH} \to \text{HCOONa} + \text{CHI}_3 \downarrow + 5\text{NaI} + 5\text{H}_2\text{O}$$

• For Acetone:

$$\text{CH}_3\text{COCH}_3 + 3\text{I}_2 + 4\text{NaOH} \to \text{CH}_3\text{COONa} + \text{CHI}_3 \downarrow + 3\text{NaI} + 3\text{H}_2\text{O}$$

Concept: Iodoform ($$\text{CHI}_3$$) is a yellow crystalline solid with a characteristic pungent odor. The Iodoform Test is a qualitative chemical test used to identify compounds containing either a methyl ketone group ($$\text{CH}_3\text{C=O}$$ ) or a secondary methyl alcohol group ($$\text{CH}_3\text{CH(OH)}$$) that can be oxidized in situ to a methyl ketone by the reagent ($$\text{I}_2 / \text{NaOH}$$).

Upon heating the organic compound with iodine in the presence of sodium hydroxide ($$\text{I}_2 / \text{NaOH}$$ or $$\text{NaOI}$$), α-halogenation occurs followed by nucleophilic cleavage of the $$\text{C--C}$$ bond, precipitating iodoform.