Answer to Question #17992 in Organic Chemistry for Lilly

Question

Phenols show a negative reaction for triidomethane test. However, when I did the experiment, phenol+iodine solution+ NaOH drop by drop + warm, I noticed that the brown colour of iodine solution was decolourised and a cloudy solution with orange droplets. The smell was that of like vinegar. This shows a negative iodoform test as no yellow precipitate was formed. Since the solution added was iodine solution and not an alkyl halide, what could the product be? I do not understand the mechanism behind the reaction. Could you please explain. Thank you.

Answer 1

When heated with of iodine phenol in the presence of caustic alkali sediment forms tetra-iodo-diphenylene-dioxide (C₆H₄I₂O)₂.