Sciencemadness Discussion Board

Hydrating Eugenol

ItsAChitzen - 30-8-2012 at 14:53

This is probably going to be facepalmingly bad, but one of the things that I want to do is to get pointers on procedure.

I have done a lot of textbook chemistry, but haven't really ever stepped in a lab. So, I was eager to try hydration on my own for the first time, and I chose eugenol for a couple of reasons:

Cheap and available

Not super simple for me

Should be able to tell by smell whether the reaction worked

I mixed 3.5 grams of eugenol with 60 mL of 20% H2SO4 solution. In retrospect, I would have reversed this. I let this go on stir at room temperature, but not too much was happening. The phases were not mixing to any appreciable degree. So, I had a bunch of quat ammonium salt lying around, and put a pinch in. Everything started churning, so I let it sit there for about 30 mins. Lots of what I think to be gas evolution.

So, time to separate. I drip a little bit of 10% sodium hydroxide solution into the mixture to make it easier for me to handle and got out a sep funnel. I filled it up and let it settle. Then, I washed twice with 10 mL DCM and put all of the aqueous in one container. I then washed the DCM layer with more of the NaOH solution. I did this to hopefully get all of quat out of the DCM, but I don't know whether this is actually needed. Once it passed isotonic, immediately all of my DCM layer, which was clearish, turned yellow. My aqueous layer turned pretty intensely burgundy. I'm guessing that this is because the quat salt had bromine ions, but could have been something unfortunate happening.

So, I know there are side reactions such as dimerization, but what do you think happened? If this story is garbage, then tell me and I will reform my obviously novice methodology. I'd just like to get some feedback. Also, if you have suggestions for a better hydration reaction, please let me know.

Mar-Vell - 31-8-2012 at 14:15

No, your story is not garbage. This is a great experiment that I think has enormous potential.

That there was a color change to both your DCM and aqueous phases is interesting, but I hardly think it indicates any destruction of your starting material (eugenol) and/or final product (hydrated eugenol?).

I recommend evaporating your DCM layer to see what might be causing the yellow color. You might have a compound which could have come from your synthesis, or, more likely, from the non-phenolic components of the Clove Oil mixture you started out with (unless of course you really used pure eugenol).

Not sure what could have caused the burgundy color reaction of the basic aqueous phase. However, if you were to add acid (HCl or H2SO4) to liberate any soluble phenolic compound, you might get a better idea of what you have. You can test for phenolic groups with alcoholic FeCl3 (which if it's eugenol, should yield a blue color; isoeugenol, a green color; something else, blue or green, I suppose). A concentrated ~45% aqueous solution of FeCl3 can be found as PCB Etchant Solution at your local Radio Shack (I guess you can add a few drops to an alcoholic solution of eugenol to see if you get the blue color). You should vac distill your eugenol and final products and compare their boiling points. If any of these products crystallize, check the melting point.

I have a few references you might like to check out. I'll get back to you on Monday. Until then, have a great weekend.

[Edited on 31-8-2012 by Mar-Vell]

ItsAChitzen - 4-9-2012 at 11:27


The DCM layer did not contain very much. I am evaporating the aqueous layer, and am getting a bunch of nonsense along with what I would expect. I will know in a bit what is in this layer.

I tried a different approach in another experiment: I used the same concentration of H2SO4, but added a stoichiometric amount of Potassium Dichromate. This time, I dripped the eugenol into the chamber over 10 minutes. I then went for the quat salt, but I noticed a pretty quick color change from light orange to dark brown. I am separating it out a evaporating the contents of the DCM as we speak. I waited until after DCM separation to neutralize. This time, no crud was formed to speak of, but I did notice some precipitation. I will find out what this is later. If anyone knows some tried and true methods of hydrating a double bond off of a benzene-like molecule, please let me know.

zed - 11-9-2012 at 14:13

This is analogous to a procedure for hydrating Safrole, that was reported in the Rhodium Archive.

It could not be described as tried and true. Some folks reported success, many reported the opposite.

If it works for Safrole, which is unproven, it might not work for Eugenol.

Do keep in mind, that the Eugenol ring differs from the Safrole ring. The presence of an OH group might actually tend to activate the benzene ring itself, in a manner that would favor attack there. Generally, ortho to the OH group.