I’ve been getting good results with PTSA + toluene. Basically, I dissolve 1g of CBD isolate in 13g of toluene, add a symbolic amount of PTSA monohydrate, headspace flush with inert gas, add 12ml @ 100C of water vapor into 100ml headspace, seal and stir 48h at 25C. I’m getting around 70% D9 + 20% D8 in crude typically but this is highly non-reproducible and non scalable.
As soon as I swap out my usual toluene for toluene from a different source or PTSA from a different source or CBD from a different source, or cook my glassware longer or shorter or use a different beaker or whatever.. it goes off and I have to painstakingly retweak my procedure.
So, after over a hundred runs of that, my theory is that it is all in the water contamination. PTSA is essentially non-soluble in toluene. The first thing I did when I got the capability was to make everything as dry as possible.. and well, the result was basically pristine 99% CBD at the end of 48h. As soon as I add back any water into the system, reaction proceeds. Add too much, reaction goes too eagerly and ends up with bad selectivity (my goal is as much D9 as possible).
I noted the PTSA as a “symbolic” amount since it seems to make no difference whether I add a single miniature spec or a whole gram or whatever in between, I cannot measure out an amount small enough to make a difference in anhydrous conditions with my batch sizes. The catalytic activity seems entirely dependent on how much PTSA can actually dissolve in toluene and that in turn seems entirely dependent on how much water there is in the system.
So.. now I’m on a quest to try and quantify the actual amount of water needed for optimal selectivity and figure out how that quantity relates to other quantities. I’m gonna try and set up a reactor with no headspace (since a significant amount of water will escape from toluene into a dry headspace when you start with PPM amounts). Gonna make super wet toluene and super dry toluene, gonna mix them in various amounts and hopefully find a repeatable pattern across differently sourced reagents.
You guys got any ideas, theories or such? What does your experience tell you?
The person that you should ask is @Roguelab he has extensive experience and incredible knowledge on that and he is most likely to give you the most accurate answer.
Wich ptsa are you using monohydrate ?
Or anhydrous ?
As for the reaction to proceed disassociation is needed so a tiny bit of water
As for tolueen it absorbs a tiny bit of water wich is sufficient to disacosiate your ptsa
Now I personally have not kept track of water content nor have I ever really dried any hardware or reagents for ptsa monohydrate reactions. Since it s not dry ( anhydrous)
There seems to be some correlation between water content and yields with several reagents
First that comes to mind is the citric acid used in a water rich reaction with beter yields than expected
As for your reactions scale differently
Remember that mixing speed is the reaction speed when reagents do not mix ( imissible)
So scaling the reaction is making sure that mixing is on par with the small scale
You could always treat it as a solid phase catalyst…
Back when I was making d8 I was using heptane and sulfuric acid a custom little process I came up with myself — but heptane and sulfuric acid are not soluble but that seemed to not matter at all and the reaction still proceeds just fine.
You can totally see the sulfuric acid mixing around in the tank and it’s left in the bottom as the first part that you pour out when you’re done.
Sure treu and at his time frame it should not be very important but ptsa can Isomerize in yust under 20 min when mixed well
I would imagine that in 48 hours the mixing is not a major parameter
But hydrodynamics are complex to figure out when scaling
I am not sure if op has coa s to confirm his yields since they don t make much sense in comparison to my finds but tolueen was never my choice of solvent and that can have a huge impact on yields
I have lost most of my curiosity along the way so no intention of trying his sop
If one looks up papers with this specific rxn the numbers he claims are akward but then again nobody is feeding steam to their vessel
And very doubtful it has the ability to do much knowing the solvent and water are imiscible
I use PTSA monohydrate. As far as I can tell though, even though its a monohydrate, it doesn’t provide any water to the reaction as the water molecules remain too tightly bound to the PTSA molecules. Otherwise I cannot explain huge swings in selectivity based off the microliters of water that I add.
About mixing - I too thought that over 48h and in a volume of ~16ml it wouldn’t make much difference so I tried a run with no stirring but that resulted in 80%+ unreacted CBD. Still seems kinda wild to me but I haven’t tried that again.
Anyways, I’m slowly getting started. First run is done, 1g of 99.6% CBD isolate, 0.1g PTSA H2O, 13g of anhydrous toluene, 11 microliters of water (enough to completely saturate the toluene), dry helium atmosphere, stirring at 800rpm. Result: approx 80% CBD, 20% D8.
Did not expect that.. I expected it to make 80%+ D8 so I’m gonna gather more data before I try coming up with any hypotheses.
While preparing new experiments, I discovered that pretty much all my runs so far have been contaminated by micrograms of aerosolized iron ions and maybe even ppm levels of HCl gas introduced into the headspace. I don’t know the significance of this yet but I believe they could be working as co-catalysts and in quite a significant way at roomtemp. Regardless, this may invalidate all my claims and theories so far about why this or that.. man what a mess, got lots of figuring stuff out to do.
If you joined one day ago with this as your first post, why would you list an existing topic you’ve provided nothing to as your featured topic in your profile?
