Epoxide Rearrangement Example

[uemura]

Uemura, Chromic and perhaps some other unknown bees studied the thermal re-arrangment of epoxides to the corresponding ketones.

This little write-up publishes some results on an epoxide re-arrangement for the anethol epoxide. The epoxide was produced in accordance with Uemura's description now also to bee found on Rhod's site (see

https://www.thevespiary.org/rhodium/Rhodium/chemistry/epoxide.html

) Two minor modifications with respect to this procedure has been performed:
1) Stirring time was only 16 hrs at a rt around 18DegC
2) Evap of the MeOH/MeCN mix has been performed under moderate vacuum (approx 200Torr) in a waterbath at 40-45DegC.

From 30 ml anethole in 300ml 1:1 mix of MeOH/MeCN with the proper 1.1 molar amount of H2O2 (30%) and 3g sodiumcarbonate (Na2CO3) stirred at rt (18DegC) for 16hrs 28,3g crude epoxide has been received. The MeOH/MeCN mix has been destilled off under reduced pressure, work-up as described. This time the crude epoxide is clear with almost no color.

Rearrangement
The crude! epoxide was loaded together with some boiling stones in a 250ml flask equipped with a small Liebig condensor. The flask is heated by means of an electric mantel. At 260DegC (760Torr adjusted) the epoxide starts to boil (measured inside the liquid). Some 'spurious explosions' caused by the bumping stones or epoxide happened without getting out of control. The reflux is continued for 90min, the inside temperature stayed at 263DegC.
After cooling down a normal pressure destillation setup was performed. The flask was heated again and between 255 and 275Degc (*) 19g of a clear yellow-green oil came over. Then the temperature dropped down, a red-brown liquid remained in the destillation flask (Temp liquid > 283DegC). This is a yield of 19g ketone from 30ml olefine, approx. 57% yield which isn't really good but isn't bad either. (**).
A bisulfite test with 1ml of the received destillate worked like a super-duper-easy confirmation, no oily precipitae, after 20sec shaking pure bisulfite compound (light yellow in white gel) appeared.

Discussion
This rearrangement test confirms the applicability of the thermal rearrangment reaction! The time of reflux may be reduced but Uemura wanted to make sure all epoxide got converted (Chromic noted some epoxides has been found after too short reflux time. Uemura also found some oily precipitate in the bisulfite for the 'just-only' destilled epoxide. Together with the quick asarone epoxide rearrangement test, it should bee proven, that the epoxidation-thermal rearrangemenbt route is a practical route to get the valuable ketones. Bees, if you have safrol around, please verify  and post the results.

(*) Adjusted 760Torr.
(**) Say you get 70% pure epoxide from the olefine and 80% ketone from pure epoxide then you have a total yield of 56%. This would fit fine. For asarone Uemura would still prefer to purify the crude epoxide even when the new run gave only a yellow, not orange-red crude epoxide.

Carpe Diem

[Rhodium]

Another great writeup! Good work, Uemura!

[sunlight]

Fantastic, we should try it with iso too.
Considering that we know nothing about thermal rearrangement of asarone epoxide, it would be necessary to make analitical tests, it could contain aldehydes or 1 ketone. Obviosly I recommend amination

[Vibrating_Lights]

The O tea for Swis is on order.
You guys are the shit. Now if that rat bastard could only find him some acetonitrile.  Oxone will have to do. Next write up will be Mdma in under 20 hrs  Otc we might have won.
VL_

[uemura]

sunlight,

Considering that we know nothing about thermal rearrangement of asarone epoxide..

'Nothing' isn't really true, see

Post 241734

(uemura: "Asarone Epoxide Rearrangment", Novel Discourse) but Uemura agrees further analysis is required.

Carpe Diem

[uemura]

A postscript note to the melting point of the p-methoxy-phenyl2propanone.

1) After standing few weeks in the freezer, uemura found the whole ketone solidified as yellow cristalls which went back to liquid at room-temperature.

2) A batch from a old run using the nitropropene/AcOH/Fe method gave the pink oil (as described by Shulgin). Ketone prepared by this method did not cristallise in the freezer.

3) Organikum gives a mp of +38DegC for the ketone which seems to be either wrong or applies only to the ultra-high-pure substance.

Merry X-Mas to the bees

[LaBTop]

Don't you LOVE this guy? He'smuch too serious at times, come on, -shit, Ins on-, lett's go to the Couch, have some fun alltogether! Time to RELAX, it's nearly CHRISTMAS, and I'm stuck here, no home formeto go to, fuck, don't you hate WOD? LäBTöp/

PS: ""or applies only to the ultra-high-pure substance"": use ONLY Glenfiddich when in utterly need of help! EtOH RHULES! The shit is comically cheap compared to all these precursor thingies!

PSII: Uemura RHULES!!!! What a devotion! Hope he's gonna donate his genes and stock them in the Hive freezer for our most promissing offspring next year! btwWhere's KrZ? Hope he's alright.Wouldnt want to miss him next year, funny little paranoid biobeatle. Showthemthemoney bro!

Whut merrykrismas? Spoiling money on unnescessairy shit, buy more precursors instead of fuckin electronic crap!
WISDOMwillWIN

[Rhodium]

Uemura: What's Organikum? Is it something like Beilstein Light Edition?

[Osmium]

An (east?) German chemistry book, containing lots of general procedures but not much theory. Comparable to Vogels, it is/was considered the standard cookbook among lots of the German chemists I've met.

[cheeseboy]

Let's say cheese was using 100% Oxone and did NOT use Bicarb to buffer it. Would this oil be OK for thermal rearrangment? Confused about epoxide/glycol/diol. Too many synonyms for cheese. Please clarify. is the BiCarb necessary if doing a thermal rearrangment instead of the acid treatment to ketone?
Cheeseboy-a whiteboy with Soul Like a black guy without soul
May The Source Bee With You Always.

[Rhodium]

Glycol = Diol, ok? Drawings of isosafrole, isosafrole glycol and isosafrole epoxide can be found here:

https://www.thevespiary.org/rhodium/Rhodium/chemistry/peracid.html

[Vibrating_Lights]

Thermal rearrangement from unbuffered oxnoe runs which yeilded epoxide/diol mix lead to mass polymerization.
VL_

[PoohBear4Ever]

So bottom line, which method of rearrangement is prefered if someone was doing a buffered oxone run?  As long as your working primarily with the epoxide, is there any increase in yields (less mechanical losses, perhaps?)...?

PB

[Chromic]

I had, just recently, a really bad failure with trying the thermal rearrangement.

I thought I'd post it for others to see. I ran a standard oxone run on 100mmol anethole as by the oxone procedure that is on Rhodium's. I distilled and got a fraction with very little forerun (a couple drops around 232-260°) that boiled 265-270° (a glasswool insulated column was used, the lit. temp of anethole ketone is 266-268°). I checked it with bisulfite and it went cloudy. (this really confused me?) I tried to form the oxime a la sonson (Na2CO3, MeOH), and I got a white solid that was NOT the ketoxime.

My lab technique was SOLID so I don't see what went wrong. I fear that not enough time was given to rearrange the epoxide () or there's other problems going on. I would test it with isosafrole but I STILL have not gotten replacement high temp thermometers.

I also recently tried a tosic acid rearrangement in perc on asarone epoxide, but got a really, really bad black tar. I'm still trying to figure that one out.

[cheeseboy]

Cheese decided to go by the book exactly. Point for point. following the Chromic Oxone epoxidation. The only subs were Toluene in place of DCM  and baking soda for the buffer (sodium bicarb)

This third attempt was the closest yet if not successful. The slurry was spun for 14 hours and the oil was taken up in toluene, coming out a dark yellow (much like MDP-2-P cheese has seen before), so cheese was excited to see what effect the H2SO4 treatment would have on this yellow oil. After around 1 hour of refluxing with 15% H2SO4 solution the oil turned darker redish brown and sank to the bottom (Ketone?) reflux was continued for another hour and then the dark brown oil was tapped off in a sep-funnel and washed with Basic washes using sodium bicarb first then KOH 5% solution then a few  plain dH2O washes. This left cheese with a murky brownish oil with a slight yellow timt to it. Not clear at all, smelling similar to the glycol. Weighing in at 12.7 gm. Cheese is going to try and vacuum distill it and see if the yellow/green ketone is hiding in there somewhere. But cheese has a feeling that it will just get darker until it turns into that burned cheesecke crap! Formic rout is looking sweeter every hour.
Cheeseboy-a whiteboy with Soul Like a black guy without soul
May The Source Bee With You Always.

[cheeseboy]

OK Big U
 
   Cheese thinks that the thermal rearrangement of the isosafrole epoxide might not work like the anethole. Only because cheese tried thermally rearranging iso epoxide for close to 2 hours at 260°C and the resulting crude oil was cleaned up with bicarb washes but DID NOT aminate when spun for 36 hrs in cyano/ammonium acetate/meoh. However, cheese has tried using buffer and not using buffer, thermally rearranging and acid treatments and the only  success has ever been with using the sodium bicarbonate buffer and the sulphuric acid reflux. In turn the oil sank the the bottom and turned into ketone.   There have been to many variables to say that the thermal rearrangement if isosafrole epoxide won't work though. Somebee will try it and see .
Cheeseboy-a whiteboy with Soul Like a black guy without soul
May The Source Bee With You Always.

[Chromic]

I've gotten yields from the thermal rearrangement with isosafrole. They were low, and I only tried the distillation once. I was never able to find the source of my error (if it was the amination or the rearrangement).    Twodogs spoke of the rearrangement working, so I'm almost positive that it does.

I finally got my thermometers, so once I get some more oxidant I plan to play with the thermal and tosic methods more.

[uemura]

Cheese,
The article by Höring Uemura came up with some time ago in the Novel discourse shows thermal rearrangement for the anethole- and isosafrole-epoxide. The epoxide was prepared by Höring via the di-bromides. Uemura was succesful with re-arrangment of the anethole epoxide (via the MeCN/MeOH route) but since he has no access to isosafrole its rearrangment couldn't be confirmed. Uemura would do a vac destillation of the crude epoxide before attempting the re-arrangment. Boiling points for the epoxide are around in the hive which should be helpful to verify the quality and amount of the product gotten in the oxone epoxidation. Carpe Diem

[cheeseboy]

Thanks Uemera!

  The crude ketone made from Oxoning Isosafrol and finally treating with H2SO4 turned out to be a brownish yellow color, but smell of ketone. You know, not so spicy like licorice, but creamy like cream soda kinda..YUMMY
Cheeseboy-a whiteboy with Soul Like a black guy without soul
May The Source Bee With You Always.