We are going to be preparing 5-iodo vanilla and there are a few ways to do this reaction .

First we start by weighing out 10 grams of potassium, iodide and 5 grams of sodium bicarbonate into a beaker .

We then weigh out 7.5 grams of pure vanillin powder. Pure vanillin is available under the RoVanil branded professional bakery suppliers .

Next we weigh out and put it into a beaker .

Prepare 12.6 grams of solid iodine .

First we place a magnetic stir bar in the beaker containing the potassium, iodide and bicarbonate and add 200 ml of water .

Then stir to dissolve .

Now add the vanillin to the well stirred solution. This won't dissolve but it will form a suspension in the liquid .

Now add the iodine to the beaker .

Now add the iodine to the suspension one portion at a time .

You should immediately see a yellow color as some of the iodine dissolves in the potassium iodide solution to form the I3-ion which is the reactive species .

Keep adding the iodine and the color will change to orange and the vanillin in suspension will appear yellow in color .

Not all the iodine will dissolve immediately .

Be left stirring for 2 hours after which you'll see the solid iodine at the bottom of the beaker slowly dissolve and react .

After 2 hours we're left with a yellow solid and a dark red solution .

There's still some free iodine in here and also some unreacted vanillin so we need to clean our product up .

Vacuum filter and dry the yellow solid then wash with .

50 ml of a very dilute sodium thiosulfate solution followed by 50 ml of cold water .

Dry the solid as much as you can on the filter but be warned this stuff doesn't like to dry .

We then dry the damp tin colored solid by putting it in a sealed container containing calcium chloride granules after a few days it had dried fairly well and was ready for recrystallization .

We recrystallized using a boiling mixture of 20% ethanol and 80% isopropyl alcohol .

The solid took around 200 ml of boiling solvent but dissolved completely without any resin .

Uncooling for 2 hours a massive needle like pale colored crystals was produced in the solution .

Filter these and dry as much as you can again on the pump .

Once again you'll find that the crystals just don't want to get dry and have a flaky consistency which makes it difficult to tell if they are actually dry .

Remove the crystals, place in a beaker and use a vacuum desiccator to get a completely dry product if you need it .

Our crystal is ready! .

Our finished product was a pale tan almost gold colored solid with an almost quantitative yield from the starting vanillin .

The product only has a very faint vanillin aroma .

This is a useful intermediate compound which can be used to make 5-hydroxy vanillin and also syringaldehyde .

Stay tuned! .