Question

Why acetamide does not give iodoform test?

Answer 1

Acetamide does not give positive Iodoform test. The reason is that if we recall the mechanism of reaction , after incorporation of three halogen atoms on the αα carbon of carbonyl carbon, there is a step where the OH- attacks at the carbonyl carbon and αα CX3 - leaves. But in acetamide there is a resonance of NH2 group with Carbonyl carbon. So the electrophilicity of Carbonyl carbon decreases and it becomes difficult to attack the less electrophilic carbon by external nucleophile because the overlap of Carbonyl carbon with N of NH2 is very strong (2p ππ - 2pππ overlap) .so the iodoform reaction is very difficult to occur for acetamide.