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FASI in Naphtha!

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Ok, did some more searching, and it seems that FASI/FASA typically won't work in naphtha, due to fumaric acid being insoluble in naphtha.

This gives me something worthwhile to experiment with. Namely:

1 - confirm that fumaric acid will not dissolve in room temperature naphtha (solubility of 1g/ 100ml would be sufficient)
2 - check to see if warming naphtha to 50c affects the solubility of fumaric acid

DMT becomes much more soluble in heated naphtha, so to my non-chemistry mind, maybe fumaric acid solubility could be affected by temperature too. If so, FASI/FASA may be possible. This was probably considered already, but maybe not, since most folks don't even consider FASI/FASA with naphtha.

If it doesn't work, I'll just have to go with a freeze precip, redissolve into xylene and then FASI. At least it should make a pretty clean salt.

I'm open for comments. Should be able to post more tonight.
 
A possible workaround for the FASI/FASA incompatibility-with-naphtha problem is to add a certain amount of the IPA or acetone (without the dissolved fumaric acid) to the naphtha first. This technique is experimental, so you could add that to your list of experiments.

DMT becomes much more soluble in heated naphtha, so to my non-chemistry mind, maybe fumaric acid solubility could be affected by temperature too.
Click to expand...
It's hard to extrapolate between widely differing compounds. Also consider how, for example, calcium hydroxide has a retrograde solubility curve, i.e. it becomes less soluble at higher temperatures. And the solubility curve for sodium chloride is virtually flat.
 
Thank you for the suggestion and guidance, Downward.

Any suggested starting point for the naphtha/IPA ratio? I'd be happy to give it a shot with a small volume (say, 50ml of the 500ml I have of saturated naphtha). If it doesn't work, I guess I would just salt it back out with acidified water then basify.
 

In this post it mentions 10% acetone in limonene MHRB extract.

Extrapolate/experimentally determine your own IPA/naphtha ratio. You can use fresh naphtha to determine what ratio works, if any. There's no need to risk wasting your extract.

Then you can apply the data to the final precipitation experiment. Don't use all the extracted naphtha at once!

I strongly suggest drying the naphtha extract with anhydrous sodium carbonate first - decanting away from the solids before adding dry IPA prior to the FASI precipitation, of course.


Happy experimenting and good luck!
 
Beautiful. That will be a bit more involved, will have to start tomorrow night when I have a bit more time.

This should be fun!
 
Success!-- it least is sure looks like it.

I saturated 99% IPA with fumaric acid, then heated 20ml of the DMT saturated naphtha in 50c water.

Adding the FASI dropwise, it was clear I was getting a desirable reaction. Each drop would cause clouds of milky white to form.

After about 3ml was added, no further clouding or color change occurred. The pic of the end product is below.

I will need to wait a few days for the precipitate to settle before reporting final weight, but I am pretty confident I will have fumarate!

So-- It is possible to FASI into heated naphtha. The only down side is that residual fumaric acid could fall out of the naphtha as it cools. I plan to redissolve in boiling hot IPA as a final clean of the product, and will weigh before and after.

I will not be running the experiment involving added xylene-- it doesn't seem necessary at this point.
 

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I had a moment of fear: what if the clouding was all just fumeric acid? So I ran a test today dripping FASI in clean (no dmt) hot naphtha, and... no clouding! That means the clouding in the dmt saturated naphtha is dmt fumarate. whew.

There was some precipitation in the naphtha I acidified yesterday, but more FASI lead to it clouding up again, so the measurements will have to wait a bit longer.
 
Interesting discovery and so simple. This could be quite useful. There must be a minimum effective temperature for this method.

Does the FASI/naphtha cloud on cooling? (The 'clean' naphtha, that is!)

Was the further clouding on re-FASI-ing with warm or cold naphtha?

Having to rely on high temperatures could be a drawback if the naphtha needs to be reheated each time FASI is added. But if the IPA present from the first precipitation is sufficient to prevent fumaric acid from crystallising in the cold that wouldn't be so much of an issue.

Have you tried dosing the naphtha with a dash of IPA instead of heating it?

The relative advantage of the method you describe is that both DMT fumarate and water are much less soluble in naphtha than they are in IPA or acetone.

It is probably worth testing this with acetone, but acetone has a much lower boiling point than IPA.


Good work Nitegazer!
 
Thank you for your continued interest Downward--

- I was able to get good clouding at 50c, but did not try any cooler than that.

- The 'clean' naphtha doesn't cloud when heated or cool. After the fumarate precipitated the solvent was clear at room temperature. I re-heated and added some more FASI, to confirm I got all the product. The first 3-4ml clouded (residual dmt in the solvent, I suppose), but then the clouding stopped with subsequent additions.

- You have a good point about the potential of present IPA negating the need for more heat. Unfortunately, I did not test for that. I also didn't test 'dosing' the naphtha with IPA without heat.

Here are pics of the product. An advantage of Naphtha is that it is more selective than xylene or d-limonene. The product looks fairly clean-- for my purposes. I will just dissolve in distilled water in order to separate from residual fumaric acid and evaporate dry.

I'll post final weight by next week.

Thank you again for your help.
 

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