Microscale Chemistry Experimentation for Teachers
16.
Iodoform reaction of ethanol
* In a small vial transfer some crystals of
solid iodine.
* Add 20 drops of ethanol.
* Care well to dissolve.
* Add 5-M NaOH drop by drop till you obtain
a uniform pale yellow colour.
* Fill the vial with water.
* Leave to decant.
* Observe the iodoform precipitate and a clear
supernatant.
You may remove the supernatant, stopper the
vial and you will get a permanent preserved sample of iodoform.
All compounds with a methyl carbinol structure
will give the iodoform reaction and
only compounds with this structure will show
this reaction.
Each of the reaction steps is demonstrated
by molecule models:
* White, black and red beads are connected
to show the structures of ethanol, ethanal and formiate particles.
* Green beads are models of iodine atoms.
* Not only the molecule of iodoform but
also those of the intermediates can be seen.