Oxidation of eugenol to vanillin

Quote: Originally posted by mnick12

The article you provided Satan mentioned isomerization taking place in a microwave assisted reaction, is plausible to do this in a home setting I mean with a standard kitchen microwave?

I have considerable experience with eugenol and I'm curious to know which oxidizer you're talking about. If I know Rhodium, it'll be palladium chloride, which should produce a ketone. However, it doesn't work. I haven't tried it, but I've read that peracids don't work either. But it may be possible to double chlorinate the tail bond and then work it up with KOH to a ketone. I may give both a go to see if either works.

There are a number of sources on google if you search 'vanillin from eugenol'.

Here's one showing the mechanism.

I'm in the middle of extracting some caffine and sorting the pictures out for a post, but I have a bunch of eugenol handy and might have a go at making some vanillin with you. I'll check back when I have some more time, maybe later tonight, and see if I can be more helpful - I'm trying to do an experiment a day at the moment

You need to be incredibly careful microwaving things like KOH. I've done that. When a drop of it spilled on the platter, it created a superheated spot. The glass is reinforced to prevent accidents, so it stores up energy rather than breaking. When I opened the microwave door and the cool air touched the platter, it literally exploded as if someone had put a huge firework in there, sending finger sized shards of glass everywhere, with me stood directly in front of it.

The bang was loud enough to temporarily deafen me in one ear and I actually took my shirt off and checked my skin in the mirror, thinking a shard may have gone into me without me noticing. That was enough to stop me touching chemistry for around six months.

Long story short, no... it's not safe. I've seen the results of what happens when it goes a tiny bit wrong first hand, and I'm not talking them up.

[Edited on 10-7-2010 by peach]

Thats interesting, 67% is not great but it is better than I expected for chromic acid. As for aniline it can be made from benzoic acid via the amide and hoffman degredation, I will be doing this next weekend. Though I dont know about sulfonation of aniline I would expect a mixture of the p and o isomers. But I may not be able to isomerize any eugenol for a while since as it turns out my other brother is going to get all 4 of his wisdom teeth removed very soon and needs the clove oil for his teeth. If I am lucky I may be to convince him to use the hydrocodone instead and let me keep the clove oil .

I just found a cleaning company selling sulphamic acid in small, cheapo bags, but they're out of stock at the moment. £4 for 50g, with VAT and delivery. Cool, since I'm only going to be doing a little.

The dental packs I've seen for emergency fillings have sesame seed oil mixed with the eugenol I think, and the eugenol is fairly expensive given the amount you get.

If you're setup for distillation, buy some clove oil and distill the eugenol out of that. Holland and Barrett (among numerous others) sell it in the UK off the shelf, so I can pick some up whenever for not a great deal - there'll be similar hippy / herbal / organic stores around you.

I wouldn't recommend A/B extracting it. I did that and it looked like this;


Whilst pure, pharmacopoeia grade eugenol looks like this;


[Edited on 12-7-2010 by peach]

I used the now infamous lab guide that is actually hosted here on SM;

Extraction of eugenol from cloves

Rather than steam distill, I started with pre-extracted clove oil. The quantities of solvents and such used in that guide are larger than they need to be, I believe to make it easier for the students to handle the small volumes.

If those are scaled up (based on the amount of oil in that quantity of dry cloves), you'll end up using hundreds of mls of DCM, or liters, for very small amounts of eugenol. Instead, I redid the guide by adding the additional material in small aliquots until I found something closer to the extract amounts required.

I needed 6ml of 5% KOH per ml of crude oil, which I found was the maximum before the extractions no longer took on any colour or change in opacity when added to the crude oil; the oil it's self was no longer changing with regards to either of these factors.

This was then washed with 1-3ml of DCM per ml of crude oil. Again, around all that's necessary to clear any scum from the aqueous KOH extract. As I approached 3ml of DCM per 1ml of crude oil, the DCM stopped taking on any colour or opacity change, indicating that more would likely be excessive.

I then acidified with vigorous stirring, slowly, using a dropping funnel and pH meter until the pH was stable at 0.999; I did this over about 45 minutes.

The oil drops back out of the aqueous phase. Again, it takes between 2-3ml of DCM per ml of crude oil to remove the suspect product. The oil disappears from the aqueous phase very rapidly. Using much more DCM per ml of crude oil is somewhat excessive.

As I say, those are the numbers I found necessary. The ranges are also not guesses, the lower number is the value needed to roughly clear a stage and the upper value is to be sure. They're quite a few times less than the quantities used in the guide, so it's unlikely I've pulled over contaminants.

I didn't test the oil. Coming from crude clove oil, I know it's going to be a majority of eugenol to begin with, and this is a lab guide specifically for extracting eugenol from the crude oil.

I could test it with iron chloride, but I know what the result will be. I can tell just by the smell what it is. Distilled eugenol also has an aroma that is quite a lot less complex and 'spicy' than crude clove oil, whereas this A/B still had quite a bit of 'clovyness' to it, along with the crude colour.

First KOH extraction. The basic aqueous is the baby puke yellow on top, the crude oil is below. Note that you'll get an emulsion if you do any serious swirling or shaking at this stage, and you don't need to


Another. KOH top, crude oil below


And another, there's no real change occurring now. KOH top, crude oil below


Extracting rubbish from the aqueous phase with DCM. This is the first wash. I did three in all. By the third, there was essentially no change occurring upon addition. If you leave the KOH extractions to stand, they may tend to 'waxy up' into a kind of waxy slushy. The DCM washes will cure that. Freebase oil in aqueous layer at the top, DCM wash on the bottom


The acidified aqueous phase is on top and the DCM is extracting the oil below


Another DCM wash, note the lack of change, the oil has been extracted. Acidified aqueous layer on top, DCM below


The product, after removing the DCM. Yield is around 50%. Not bad considering the crude leaf oil is usually around 70% eugenol. But that's no where near clean


A/B SIMPLIFICATION;

Extract with 6ml 5% KOH per ml crude oil - keep aqueous
Wash aqueous with 1-3ml DCM per ml crude oil - keep aqueous
Acidify to pH 1, stable
Extract with 2-3ml DCM per ml crude oil - keep organic
Remove solvent

A BETTER IDEA;

Vacuum distillation through a vigreux

[Edited on 12-7-2010 by peach]